update

AI_prompt.txt

@@ -13,3 +13,41 @@ Role: Principal Systems Architect & Lead Software Engineer.Objective: Implement
 
 
 Create a walkthrough for Julia service-A service sending a mix-content chat message to Julia service-B. the chat message must includes 
+
+
+
+
+
+
+I updated the following:
+- NATSBridge.jl. Essentially I add NATS_connection keyword and new publish_message function to support the keyword. 
+
+Use them and ONLY them as ground truth.
+
+Then update the following files accordingly:
+- architecture.md
+- implementation.md
+
+All API should be semantically consistent and naming should be consistent across the board.
+
+
+
+
+
+
+
+
+
+Task: Update NATSBridge.js to reflect recent changes in NATSBridge.jl and docs
+
+Context: NATSBridge.jl and docs has been updated.
+
+Requirements:
+
+Source of Truth: Treat the updated NATSBridge.jl and docs as the definitive source.
+API Consistency: Ensure the Main Package API (e.g., smartsend(), publish_message()) uses consistent naming across all three supported languages.
+Ecosystem Variance: Low-level native functions (e.g., NATS.connect(), JSON.read()) should follow the conventions of the specific language ecosystem and do not require cross-language consistency.
+
+
+
+

README.md

@@ -173,7 +173,7 @@ from nats_bridge import smartsend
 
 # Send a text message
 data = [("message", "Hello World", "text")]
-env, env_json_str = smartsend("/chat/room1", data, nats_url="nats://localhost:4222")
+env, env_json_str = smartsend("/chat/room1", data, broker_url="nats://localhost:4222")
 print("Message sent!")
 ```
 
@@ -185,7 +185,7 @@ const { smartsend } = require('./src/NATSBridge');
 // Send a text message
 const { env, env_json_str } = await smartsend("/chat/room1", [
     { dataname: "message", data: "Hello World", type: "text" }
-], { natsUrl: "nats://localhost:4222" });
+], { broker_url: "nats://localhost:4222" });
 
 console.log("Message sent!");
 ```
@@ -197,7 +197,7 @@ using NATSBridge
 
 # Send a text message
 data = [("message", "Hello World", "text")]
-env, env_json_str = NATSBridge.smartsend("/chat/room1", data; nats_url="nats://localhost:4222")
+env, env_json_str = NATSBridge.smartsend("/chat/room1", data; broker_url="nats://localhost:4222")
 println("Message sent!")
 ```
 
@@ -313,7 +313,7 @@ from nats_bridge import smartsend
 env, env_json_str = smartsend(
     subject,                           # NATS subject to publish to
     data,                              # List of (dataname, data, type) tuples
-    nats_url="nats://localhost:4222",  # NATS server URL
+    broker_url="nats://localhost:4222",  # NATS server URL
     fileserver_url="http://localhost:8080",  # File server URL
     fileserver_upload_handler=plik_oneshot_upload,  # Upload handler function
     size_threshold=1_000_000,          # Threshold in bytes (default: 1MB)
@@ -337,18 +337,18 @@ const { env, env_json_str } = await smartsend(
     subject,                           // NATS subject
     data,                              // Array of {dataname, data, type}
     {
-        natsUrl: "nats://localhost:4222",
+        broker_url: "nats://localhost:4222",
-        fileserverUrl: "http://localhost:8080",
+        fileserver_url: "http://localhost:8080",
-        fileserverUploadHandler: customUploadHandler,
+        fileserver_upload_handler: customUploadHandler,
-        sizeThreshold: 1_000_000,
+        size_threshold: 1_000_000,
-        correlationId: "custom-id",
+        correlation_id: "custom-id",
-        msgPurpose: "chat",
+        msg_purpose: "chat",
-        senderName: "NATSBridge",
+        sender_name: "NATSBridge",
-        receiverName: "",
+        receiver_name: "",
-        receiverId: "",
+        receiver_id: "",
-        replyTo: "",
+        reply_to: "",
-        replyToMsgId: "",
+        reply_to_msg_id: "",
-        isPublish: true                  // Whether to automatically publish to NATS
+        is_publish: true                  // Whether to automatically publish to NATS
     }
 );
 ```
@@ -361,9 +361,9 @@ using NATSBridge
 env, env_json_str = NATSBridge.smartsend(
     subject,                           # NATS subject
     data::AbstractArray{Tuple{String, Any, String}};  # List of (dataname, data, type)
-    nats_url::String = "nats://localhost:4222",
+    broker_url::String = "nats://localhost:4222",
     fileserver_url = "http://localhost:8080",
-    fileserverUploadHandler::Function = plik_oneshot_upload,
+    fileserver_upload_handler::Function = plik_oneshot_upload,
     size_threshold::Int = 1_000_000,
     correlation_id::Union{String, Nothing} = nothing,
     msg_purpose::String = "chat",
@@ -372,7 +372,8 @@ env, env_json_str = NATSBridge.smartsend(
     receiver_id::String = "",
     reply_to::String = "",
     reply_to_msg_id::String = "",
-    is_publish::Bool = true            # Whether to automatically publish to NATS
+    is_publish::Bool = true,          # Whether to automatically publish to NATS
+    NATS_connection::Union{NATS.Connection, Nothing} = nothing  # Pre-existing NATS connection (optional, saves connection overhead)
 )
 # Returns: (msgEnvelope_v1, JSON string)
 # - env: msgEnvelope_v1 object with all envelope metadata and payloads
@@ -423,9 +424,9 @@ const env = await smartreceive(
 using NATSBridge
 
 # Note: msg is a NATS.Msg object passed from the subscription callback
-env, env_json_str = NATSBridge.smartreceive(
+env = NATSBridge.smartreceive(
     msg::NATS.Msg;
-    fileserverDownloadHandler::Function = _fetch_with_backoff,
+    fileserver_download_handler::Function = _fetch_with_backoff,
     max_retries::Int = 5,
     base_delay::Int = 100,
     max_delay::Int = 5000
@@ -433,6 +434,35 @@ env, env_json_str = NATSBridge.smartreceive(
 # Returns: Dict with envelope metadata and payloads array
 ```
 
+### publish_message
+
+Publish a message to a NATS subject. This function is available in Julia with two overloads:
+
+#### Julia
+
+**Using broker URL (creates new connection):**
+```julia
+using NATSBridge, NATS
+
+# Publish with URL - creates a new connection
+NATSBridge.publish_message(
+    "nats://localhost:4222",  # broker_url
+    "/chat/room1",            # subject
+    "{\"correlation_id\":\"abc123\"}",  # message
+    "abc123"                  # correlation_id
+)
+```
+
+**Using pre-existing connection (saves connection overhead):**
+```julia
+using NATSBridge, NATS
+
+# Create connection once and reuse
+conn = NATS.connect("nats://localhost:4222")
+NATSBridge.publish_message(conn, "/chat/room1", "{\"correlation_id\":\"abc123\"}", "abc123")
+# Connection is automatically drained after publish
+```
+
 ---
 
 ## Payload Types
@@ -488,7 +518,7 @@ smartsend("/topic", data, fileserver_url="http://localhost:8080")
 ```javascript
 await smartsend("/topic", [
     { dataname: "file", data: largeData, type: "binary" }
-], { fileserverUrl: "http://localhost:8080" });
+], { fileserver_url: "http://localhost:8080" });
 ```
 
 #### Julia
@@ -529,7 +559,7 @@ const { env, env_json_str } = await smartsend("/chat/room1", [
     { dataname: "user_avatar", data: image_data, type: "image" },
     { dataname: "large_document", data: large_file_data, type: "binary" }
 ], {
-    fileserverUrl: "http://localhost:8080"
+    fileserver_url: "http://localhost:8080"
 });
 ```
 
@@ -653,9 +683,10 @@ from nats_bridge import smartsend
 env, env_json_str = smartsend(
     "/device/command",
     [("command", {"action": "read_sensor"}, "dictionary")],
+    broker_url="nats://localhost:4222",
     reply_to="/device/response"
 )
-# env: msgEnvelope_v1 object
+# env: MessageEnvelope object
 # env_json_str: JSON string for publishing to NATS
 
 # The env_json_str can also be published directly using NATS request-reply pattern
@@ -670,18 +701,24 @@ from nats_bridge import smartreceive, smartsend
 
 # Configuration
 SUBJECT = "/device/command"
-REPLY_SUBJECT = "/device/response"
 NATS_URL = "nats://localhost:4222"
 
 async def main():
     nc = await nats.connect(NATS_URL)
     
     async def message_handler(msg):
+        # Receive and parse the incoming message envelope
         env = smartreceive(msg.data)
+        
+        # Extract reply_to from the envelope metadata
+        reply_to = env["reply_to"]
+        
         for dataname, data, type in env["payloads"]:
             if data.get("action") == "read_sensor":
                 response = {"sensor_id": "sensor-001", "value": 42.5}
-                smartsend(REPLY_SUBJECT, [("data", response, "dictionary")])
+                # Send response to the reply_to subject from the request
+                if reply_to:
+                    smartsend(reply_to, [("data", response, "dictionary")])
     
     sid = await nc.subscribe(SUBJECT, cb=message_handler)
     await asyncio.sleep(120)
@@ -697,7 +734,8 @@ const { smartsend } = require('./src/NATSBridge');
 const { env, env_json_str } = await smartsend("/device/command", [
     { dataname: "command", data: { action: "read_sensor" }, type: "dictionary" }
 ], {
-    replyTo: "/device/response"
+    broker_url: "nats://localhost:4222",
+    reply_to: "/device/response"
 });
 ```
 
@@ -708,7 +746,6 @@ const { connect } = require('nats');
 
 // Configuration
 const SUBJECT = "/device/command";
-const REPLY_SUBJECT = "/device/response";
 const NATS_URL = "nats://localhost:4222";
 
 async function main() {
@@ -718,16 +755,23 @@ async function main() {
     
     for await (const msg of sub) {
         const env = await smartreceive(msg);
+        
+        // Extract reply_to from the envelope metadata
+        const replyTo = env["reply_to"];
+        
         for (const payload of env.payloads) {
             if (payload.dataname === "command" && payload.data.action === "read_sensor") {
                 const response = { sensor_id: "sensor-001", value: 42.5 };
-                await smartsend(REPLY_SUBJECT, [
+                // Send response to the reply_to subject from the request
+                if (replyTo) {
+                    await smartsend(replyTo, [
                         { dataname: "data", data: response, type: "dictionary" }
                     ]);
                 }
             }
         }
     }
+}
 
 main();
 ```
@@ -739,6 +783,7 @@ using NATSBridge
 env, env_json_str = NATSBridge.smartsend(
     "/device/command",
     [("command", Dict("action" => "read_sensor"), "dictionary")];
+    broker_url="nats://localhost:4222",
     reply_to="/device/response"
 )
 ```
@@ -749,17 +794,23 @@ using NATS, NATSBridge
 
 # Configuration
 const SUBJECT = "/device/command"
-const REPLY_SUBJECT = "/device/response"
 const NATS_URL = "nats://localhost:4222"
 
 function test_responder()
     conn = NATS.connect(NATS_URL)
     NATS.subscribe(conn, SUBJECT) do msg
-        env, env_json_str = NATSBridge.smartreceive(msg, fileserverDownloadHandler)
+        env = NATSBridge.smartreceive(msg, fileserver_download_handler=_fetch_with_backoff)
+        
+        # Extract reply_to from the envelope metadata
+        reply_to = env["reply_to"]
+        
         for (dataname, data, type) in env["payloads"]
             if dataname == "command" && data["action"] == "read_sensor"
                 response = Dict("sensor_id" => "sensor-001", "value" => 42.5)
-                smartsend(REPLY_SUBJECT, [("data", response, "dictionary")])
+                # Send response to the reply_to subject from the request
+                if !isempty(reply_to)
+                    smartsend(reply_to, [("data", response, "dictionary")])
+                end
             end
         end
     end
@@ -790,7 +841,7 @@ async def main():
     
     # Send sensor data
     data = [("temperature", "25.5", "text"), ("humidity", 65, "dictionary")]
-    smartsend("/device/sensors", data, nats_url="nats://localhost:4222")
+    smartsend("/device/sensors", data, broker_url="nats://localhost:4222")
     
     # Receive commands - msg comes from the callback
     async def message_handler(msg):

docs/architecture.md

@@ -18,9 +18,9 @@ The system uses **handler functions** to abstract file server operations, allowi
 ```julia
 # Upload handler - uploads data to file server and returns URL
 # The handler is passed to smartsend as fileserver_upload_handler parameter
-# It receives: (file_server_url::String, dataname::String, data::Vector{UInt8})
+# It receives: (fileserver_url::String, dataname::String, data::Vector{UInt8})
 # Returns: Dict{String, Any} with keys: "status", "uploadid", "fileid", "url"
-fileserver_upload_handler(file_server_url::String, dataname::String, data::Vector{UInt8})::Dict{String, Any}
+fileserver_upload_handler(fileserver_url::String, dataname::String, data::Vector{UInt8})::Dict{String, Any}
 
 # Download handler - fetches data from file server URL with exponential backoff
 # The handler is passed to smartreceive as fileserver_download_handler parameter
@@ -40,8 +40,8 @@ The system uses a **standardized list-of-tuples format** for all payload operati
 # Input format for smartsend (always a list of tuples with type info)
 [(dataname1, data1, type1), (dataname2, data2, type2), ...]
 
-# Output format for smartreceive (returns a dictionary with payloads field containing list of tuples)
+# Output format for smartreceive (returns a dictionary-like object with payloads field containing list of tuples)
-# Returns: Dict with envelope metadata and payloads field containing Vector{Tuple{String, Any, String}}
+# Returns: Dict-like object with envelope metadata and payloads field containing Vector{Tuple{String, Any, String}}
 # {
 #   "correlation_id": "...",
 #   "msg_id": "...",
@@ -369,6 +369,31 @@ graph TD
 
 ## Implementation Details
 
+### API Consistency Across Languages
+
+**High-Level API (Consistent Across All Languages):**
+- `smartsend(subject, data, ...)` - Main publishing function
+- `smartreceive(msg, ...)` - Main receiving function
+- Message envelope structure (`msg_envelope_v1` / `MessageEnvelope`)
+- Payload structure (`msg_payload_v1` / `MessagePayload`)
+- Transport strategy (direct vs link based on size threshold)
+- Supported payload types: text, dictionary, table, image, audio, video, binary
+
+**Low-Level Native Functions (Language-Specific Conventions):**
+- Julia: `NATS.connect()`, `publish_message()`, function overloading
+- JavaScript: `nats.js` client, native async/await patterns
+- Python: `nats-python` client, native async/await patterns
+
+**Connection Reuse Pattern:**
+- **Julia:** Uses `NATS_connection` keyword parameter with function overloading
+- **JavaScript/Python:** Achieved by creating NATS client outside the function and reusing it in custom handlers
+
+**Note on `is_publish`:**
+- `is_publish` is simply a switch to control automatic publishing
+- When `true` (default): Message is published to NATS automatically
+- When `false`: Returns `(env, env_json_str)` without publishing, allowing manual publishing
+- Connection reuse is achieved separately by creating NATS client outside the function
+
 ### Julia Implementation
 
 #### Dependencies
@@ -395,10 +420,25 @@ function smartsend(
   receiver_id::String = "",
   reply_to::String = "",
   reply_to_msg_id::String = "",
-  is_publish::Bool = true   # Whether to automatically publish to NATS
+  is_publish::Bool = true,   # Whether to automatically publish to NATS
+  NATS_connection::Union{NATS.Connection, Nothing} = nothing  # Pre-existing NATS connection (optional, saves connection overhead)
 )
 ```
 
+**Keyword Parameter - NATS_connection:**
+- `NATS_connection::Union{NATS.Connection, Nothing} = nothing` - Pre-existing NATS connection. When provided, `smartsend` uses this connection instead of creating a new one, avoiding the overhead of connection establishment. This is useful for high-frequency publishing scenarios where connection reuse provides performance benefits.
+
+**Connection Handling Logic:**
+```julia
+if is_publish == false
+  # skip publish a message
+elseif is_publish == true && NATS_connection === nothing
+  publish_message(broker_url, subject, env_json_str, cid)  # Creates new connection
+elseif is_publish == true && NATS_connection !== nothing
+  publish_message(NATS_connection, subject, env_json_str, cid)  # Uses provided connection
+end
+```
+
 **Return Value:**
 - Returns a tuple `(env, env_json_str)` where:
   - `env::msg_envelope_v1` - The envelope object containing all metadata and payloads
@@ -442,10 +482,10 @@ end
 ```
 
 **Output Format:**
-- Returns a dictionary (key-value map) containing all envelope fields:
+- Returns a JSON object (dictionary) containing all envelope fields:
   - `correlation_id`, `msg_id`, `timestamp`, `send_to`, `msg_purpose`, `sender_name`, `sender_id`, `receiver_name`, `receiver_id`, `reply_to`, `reply_to_msg_id`, `broker_url`
   - `metadata` - Message-level metadata dictionary
-  - `payloads` - List of dictionaries, each containing deserialized payload data
+  - `payloads` - List of tuples, each containing `(dataname, data, type)` with deserialized payload data
 
 **Process Flow:**
 1. Parse the JSON envelope to extract all fields
@@ -459,6 +499,57 @@ end
 
 **Note:** The `fileserver_download_handler` receives `(url::String, max_retries::Int, base_delay::Int, max_delay::Int, correlation_id::String)` and returns `Vector{UInt8}`.
 
+#### publish_message Function
+
+The `publish_message` function provides two overloads for publishing messages to NATS:
+
+**Overload 1 - URL-based publishing (creates new connection):**
+```julia
+function publish_message(broker_url::String, subject::String, message::String, correlation_id::String)
+  conn = NATS.connect(broker_url)  # Create NATS connection
+  publish_message(conn, subject, message, correlation_id)
+end
+```
+
+**Overload 2 - Connection-based publishing (uses pre-existing connection):**
+```julia
+function publish_message(conn::NATS.Connection, subject::String, message::String, correlation_id::String)
+  try
+    NATS.publish(conn, subject, message)  # Publish message to NATS
+    log_trace(correlation_id, "Message published to $subject")  # Log successful publish
+  finally
+    NATS.drain(conn)  # Ensure connection is closed properly
+  end
+end
+```
+
+**Use Case:** Use the connection-based overload when you already have an established NATS connection and want to publish multiple messages without the overhead of creating a new connection for each publish. This is a Julia-specific optimization that leverages function overloading.
+
+**Integration with smartsend:**
+```julia
+# When NATS_connection is provided to smartsend, it uses the connection-based publish_message
+env, env_json_str = smartsend(
+    "my.subject",
+    [("data", payload_data, "type")],
+    NATS_connection=my_connection,  # Pre-existing connection
+    is_publish=true
+)
+# Uses: publish_message(NATS_connection, subject, env_json_str, cid)
+
+# When NATS_connection is not provided, it uses the URL-based publish_message
+env, env_json_str = smartsend(
+    "my.subject",
+    [("data", payload_data, "type")],
+    broker_url="nats://localhost:4222",
+    is_publish=true
+)
+# Uses: publish_message(broker_url, subject, env_json_str, cid)
+```
+
+**API Consistency Note:**
+- **High-level API (smartsend, smartreceive):** Uses consistent naming across all three languages (Julia, JavaScript, Python/Micropython)
+- **Low-level native functions (NATS.connect(), publish_message()):** Follow the conventions of the specific language ecosystem and do not require cross-language consistency
+
 ### JavaScript Implementation
 
 #### Dependencies
@@ -489,13 +580,15 @@ async function smartsend(
 - `receiver_id` (String) - Message receiver ID (default: `""`)
 - `reply_to` (String) - Topic to reply to (default: `""`)
 - `reply_to_msg_id` (String) - Message ID this message is replying to (default: `""`)
+- `is_publish` (Boolean) - Whether to automatically publish the message to NATS (default: `true`)
 - `fileserver_upload_handler` (Function) - Custom upload handler function
 
+**Note:** JavaScript uses `is_publish` option (instead of `NATS_connection` keyword) to control automatic publishing behavior. Connection reuse can be achieved by creating a NATS client outside the function and reusing it in a custom `fileserver_upload_handler` or custom publish implementation.
+
 **Return Value:**
 - Returns a Promise that resolves to an object containing:
   - `env` - The envelope object containing all metadata and payloads
   - `env_json_str` - JSON string representation of the envelope for publishing
-  - `published` - Boolean indicating whether the message was automatically published to NATS
 
 **Input Format:**
 - `data` - **Must be a list of (dataname, data, type) tuples**: `[(dataname1, data1, "type1"), (dataname2, data2, "type2"), ...]`
@@ -531,7 +624,7 @@ async function smartreceive(msg, options = {})
 - Returns a Promise that resolves to an object containing all envelope fields:
   - `correlation_id`, `msg_id`, `timestamp`, `send_to`, `msg_purpose`, `sender_name`, `sender_id`, `receiver_name`, `receiver_id`, `reply_to`, `reply_to_msg_id`, `broker_url`
   - `metadata` - Message-level metadata dictionary
-  - `payloads` - List of dictionaries, each containing deserialized payload data with keys: `dataname`, `data`, `payload_type`
+  - `payloads` - List of tuples, each containing `(dataname, data, type)` with deserialized payload data
 
 **Process Flow:**
 1. Parse the JSON envelope to extract all fields
@@ -557,26 +650,40 @@ async function smartreceive(msg, options = {})
 #### smartsend Function
 
 ```python
-async def smartsend(
+def smartsend(
     subject: str,
     data: List[Tuple[str, Any, str]],  # List of (dataname, data, type) tuples
-    options: Dict = {}
+    broker_url: str = DEFAULT_BROKER_URL,
-)
+    fileserver_url: str = DEFAULT_FILESERVER_URL,
+    fileserver_upload_handler: Callable = plik_oneshot_upload,
+    size_threshold: int = DEFAULT_SIZE_THRESHOLD,
+    correlation_id: Union[str, None] = None,
+    msg_purpose: str = "chat",
+    sender_name: str = "NATSBridge",
+    receiver_name: str = "",
+    receiver_id: str = "",
+    reply_to: str = "",
+    reply_to_msg_id: str = "",
+    is_publish: bool = True
+) -> Tuple[MessageEnvelope, str]
 ```
 
 **Options:**
 - `broker_url` (str) - NATS server URL (default: `"nats://localhost:4222"`)
 - `fileserver_url` (str) - Base URL of the file server (default: `"http://localhost:8080"`)
 - `size_threshold` (int) - Threshold in bytes for transport selection (default: `1048576` = 1MB)
-- `correlation_id` (str) - Optional correlation ID for tracing
+- `correlation_id` (str) - Optional correlation ID for tracing (auto-generated if None)
 - `msg_purpose` (str) - Purpose of the message (default: `"chat"`)
 - `sender_name` (str) - Sender name (default: `"NATSBridge"`)
 - `receiver_name` (str) - Message receiver name (default: `""`)
 - `receiver_id` (str) - Message receiver ID (default: `""`)
 - `reply_to` (str) - Topic to reply to (default: `""`)
 - `reply_to_msg_id` (str) - Message ID this message is replying to (default: `""`)
+- `is_publish` (bool) - Whether to automatically publish the message to NATS (default: `True`)
 - `fileserver_upload_handler` (Callable) - Custom upload handler function
 
+**Note:** Python uses `is_publish` parameter (instead of `NATS_connection` keyword) to control automatic publishing behavior. Connection reuse can be achieved by creating a NATS client outside the function and reusing it in a custom `fileserver_upload_handler` or custom publish implementation.
+
 **Return Value:**
 - Returns a tuple `(env, env_json_str)` where:
   - `env` - The envelope dictionary containing all metadata and payloads
@@ -616,7 +723,7 @@ async def smartreceive(
 - `correlation_id` (str) - Optional correlation ID for tracing
 
 **Output Format:**
-- Returns a dictionary containing all envelope fields:
+- Returns a JSON object (dictionary) containing all envelope fields:
   - `correlation_id`, `msg_id`, `timestamp`, `send_to`, `msg_purpose`, `sender_name`, `sender_id`, `receiver_name`, `receiver_id`, `reply_to`, `reply_to_msg_id`, `broker_url`
   - `metadata` - Message-level metadata dictionary
   - `payloads` - List of tuples, each containing `(dataname, data, payload_type)` with deserialized payload data
@@ -824,7 +931,7 @@ async def smartreceive(
 
 **Use Case:** Full-featured chat system supporting rich media. User can send text, small images directly, or upload large files that get uploaded to HTTP server and referenced via URLs. Claim-check pattern ensures reliable delivery tracking for all message components across all platforms.
 
-**Implementation Note:** The `smartreceive` function iterates through all payloads in the envelope and processes each according to its transport type. See the standard API format in Section 1: `msgEnvelope_v1` supports `AbstractArray{msgPayload_v1}` for multiple payloads.
+**Implementation Note:** The `smartreceive` function iterates through all payloads in the envelope and processes each according to its transport type. See the standard API format in Section 1: `msg_envelope_v1` supports `Vector{msg_payload_v1}` for multiple payloads.
 
 ## Performance Considerations
 

docs/implementation.md

@@ -28,9 +28,9 @@ The system uses **handler functions** to abstract file server operations, allowi
 ```julia
 # Upload handler - uploads data to file server and returns URL
 # The handler is passed to smartsend as fileserver_upload_handler parameter
-# It receives: (file_server_url::String, dataname::String, data::Vector{UInt8})
+# It receives: (fileserver_url::String, dataname::String, data::Vector{UInt8})
 # Returns: Dict{String, Any} with keys: "status", "uploadid", "fileid", "url"
-fileserver_upload_handler(file_server_url::String, dataname::String, data::Vector{UInt8})::Dict{String, Any}
+fileserver_upload_handler(fileserver_url::String, dataname::String, data::Vector{UInt8})::Dict{String, Any}
 
 # Download handler - fetches data from file server URL with exponential backoff
 # The handler is passed to smartreceive as fileserver_download_handler parameter
@@ -148,10 +148,12 @@ NATSBridge is designed for seamless communication between Julia, JavaScript, and
 ### Example: Julia ↔ Python ↔ JavaScript
 
 ```julia
-# Julia sender
+# Julia sender - smartsend returns (env, env_json_str)
 using NATSBridge
 data = [("message", "Hello from Julia!", "text")]
-smartsend("/cross_platform", data, broker_url="nats://localhost:4222")
+env, env_json_str = smartsend("/cross_platform", data, broker_url="nats://localhost:4222")
+# env: msg_envelope_v1 with all metadata and payloads
+# env_json_str: JSON string for publishing
 ```
 
 ```javascript
@@ -165,7 +167,7 @@ const env = await smartreceive(msg);
 # Python sender
 from nats_bridge import smartsend
 data = [("response", "Hello from Python!", "text")]
-smartsend("/cross_platform", data, nats_url="nats://localhost:4222")
+smartsend("/cross_platform", data, broker_url="nats://localhost:4222")
 ```
 
 All three platforms can communicate seamlessly using the same NATS subjects and data format.
@@ -314,6 +316,31 @@ julia test/scenario3_julia_to_julia.jl
 node test/scenario3_julia_to_julia.js
 ```
 
+## API Consistency Across Languages
+
+**High-Level API (Consistent Across All Languages):**
+- `smartsend(subject, data, ...)` - Main publishing function
+- `smartreceive(msg, ...)` - Main receiving function
+- Message envelope structure (`msg_envelope_v1` / `MessageEnvelope`)
+- Payload structure (`msg_payload_v1` / `MessagePayload`)
+- Transport strategy (direct vs link based on size threshold)
+- Supported payload types: text, dictionary, table, image, audio, video, binary
+
+**Low-Level Native Functions (Language-Specific Conventions):**
+- Julia: `NATS.connect()`, `publish_message()`, function overloading
+- JavaScript: `nats.js` client, native async/await patterns
+- Python: `nats-python` client, native async/await patterns
+
+**Connection Reuse Pattern - Key Differences:**
+- **Julia:** Uses `NATS_connection` keyword parameter with function overloading for automatic connection management
+- **JavaScript/Python:** Achieved by creating NATS client outside the function and reusing it in custom handlers or custom publish implementations
+
+**Why the Difference?**
+- Julia supports function overloading and keyword arguments, allowing `NATS_connection` to be passed as an optional parameter
+- JavaScript/Python use a simpler `is_publish` option to control automatic publishing
+- `is_publish` is simply a switch: when `true`, publish automatically; when `false`, return `(env, env_json_str)` without publishing
+- For connection reuse in JavaScript/Python, create a NATS client once and reuse it in your custom `fileserver_upload_handler` or custom publish logic
+
 ## Usage
 
 ### Scenario 1: Command & Control (Small Dictionary)
@@ -324,12 +351,41 @@ node test/scenario3_julia_to_julia.js
 ```julia
 using NATSBridge
 
-# Subscribe to control subject
+# Send small dictionary config (wrapped in list with type)
-# Parse JSON envelope
+config = Dict("step_size" => 0.01, "iterations" => 1000, "threshold" => 0.5)
-# Execute simulation with parameters
+env, env_json_str = smartsend(
-# Send acknowledgment
+    "control",
+    [("config", config, "dictionary")],
+    broker_url="nats://localhost:4222"
+)
+# env: msg_envelope_v1 with all metadata and payloads
+# env_json_str: JSON string for publishing
 ```
 
+**Julia (Sender/Receiver) with NATS_connection for connection reuse:**
+```julia
+using NATSBridge
+
+# Create connection once for high-frequency publishing
+conn = NATS.connect("nats://localhost:4222")
+
+# Send multiple messages using the same connection (saves connection overhead)
+for i in 1:100
+    config = Dict("iteration" => i, "data" => rand())
+    smartsend(
+        "control",
+        [("config", config, "dictionary")],
+        NATS_connection=conn,  # Reuse connection
+        is_publish=true
+    )
+end
+
+# Close connection when done
+NATS.close(conn)
+```
+
+**Use Case:** High-frequency publishing scenarios where connection reuse provides performance benefits by avoiding the overhead of establishing a new NATS connection for each message.
+
 **JavaScript (Sender/Receiver):**
 ```javascript
 const { smartsend } = require('./src/NATSBridge');
@@ -342,9 +398,39 @@ const config = {
     threshold: 0.5
 };
 
+// Use is_publish option to control automatic publishing
 await smartsend("control", [
     { dataname: "config", data: config, type: "dictionary" }
-]);
+], {
+    is_publish: true  // Automatically publish to NATS
+});
+```
+
+**Connection Reuse in JavaScript:**
+To achieve connection reuse in JavaScript, create a NATS client outside the function and use it in a custom `fileserver_upload_handler` or custom publish implementation:
+
+```javascript
+const { connect } = require('nats');
+const { smartsend } = require('./src/NATSBridge');
+
+// Create connection once
+const nc = await connect({ servers: ['nats://localhost:4222'] });
+
+// Send multiple messages using the same connection
+for (let i = 0; i < 100; i++) {
+    const config = { iteration: i, data: Math.random() };
+    
+    // Option 1: Use is_publish=false and publish manually with your connection
+    const { env, env_json_str } = await smartsend("control", [
+        { dataname: "config", data: config, type: "dictionary" }
+    ], { is_publish: false });
+    
+    // Publish with your existing connection
+    await nc.publish("control", env_json_str);
+}
+
+// Close connection when done
+await nc.close();
 ```
 
 **Python/Micropython (Sender/Receiver):**
@@ -359,7 +445,32 @@ config = {
     "threshold": 0.5
 }
 
-smartsend("control", [("config", config, "dictionary")])
+# Use is_publish parameter to control automatic publishing
+smartsend("control", [("config", config, "dictionary")], is_publish=True)
+```
+
+**Connection Reuse in Python:**
+To achieve connection reuse in Python, create a NATS client outside the function and use it in a custom `fileserver_upload_handler` or custom publish implementation:
+
+```python
+from nats_bridge import smartsend
+import nats
+
+# Create connection once
+nc = await nats.connect("nats://localhost:4222")
+
+# Send multiple messages using the same connection
+for i in range(100):
+    config = {"iteration": i, "data": random.random()}
+    
+    # Option 1: Use is_publish=False and publish manually with your connection
+    env, env_json_str = smartsend("control", [("config", config, "dictionary")], is_publish=False)
+    
+    # Publish with your existing connection
+    await nc.publish("control", env_json_str)
+
+# Close connection when done
+await nc.close()
 ```
 
 ### Basic Multi-Payload Example
@@ -372,12 +483,12 @@ from nats_bridge import smartsend
 smartsend(
     "/test",
     [("dataname1", data1, "dictionary"), ("dataname2", data2, "table")],
-    nats_url="nats://localhost:4222",
+    broker_url="nats://localhost:4222",
     fileserver_url="http://localhost:8080"
 )
 
 # Even single payload must be wrapped in a list with type
-smartsend("/test", [("single_data", mydata, "dictionary")], nats_url="nats://localhost:4222")
+smartsend("/test", [("single_data", mydata, "dictionary")], broker_url="nats://localhost:4222")
 ```
 
 #### Python/Micropython (Receiver)
@@ -459,12 +570,127 @@ df = DataFrame(
     category = rand(["A", "B", "C"], 10_000_000)
 )
 
-# Send via smartsend - wrapped in a list (type is part of each tuple)
+# Send via smartsend - wrapped in list with type
-env, env_json_str = smartsend("analysis_results", [("table_data", df, "table")], broker_url="nats://localhost:4222")
+# Large payload will use link transport (HTTP fileserver)
-# env: msg_envelope_v1 object with all metadata and payloads
+env, env_json_str = smartsend(
-# env_json_str: JSON string representation of the envelope for publishing
+    "analysis_results",
+    [("table_data", df, "table")],
+    broker_url="nats://localhost:4222",
+    fileserver_url="http://localhost:8080"
+)
+# env: msg_envelope_v1 with all metadata and payloads
+# env_json_str: JSON string for publishing
 ```
 
+#### smartsend Function Signature (Julia)
+
+```julia
+function smartsend(
+  subject::String,
+  data::AbstractArray{Tuple{String, Any, String}, 1};  # List of (dataname, data, type) tuples
+  broker_url::String = DEFAULT_BROKER_URL,  # NATS server URL
+  fileserver_url = DEFAULT_FILESERVER_URL,
+  fileserver_upload_handler::Function = plik_oneshot_upload,
+  size_threshold::Int = DEFAULT_SIZE_THRESHOLD,
+  correlation_id::Union{String, Nothing} = nothing,
+  msg_purpose::String = "chat",
+  sender_name::String = "NATSBridge",
+  receiver_name::String = "",
+  receiver_id::String = "",
+  reply_to::String = "",
+  reply_to_msg_id::String = "",
+  is_publish::Bool = true,
+  NATS_connection::Union{NATS.Connection, Nothing} = nothing  # Pre-existing NATS connection (optional)
+)
+```
+
+**New Keyword Parameter:**
+- `NATS_connection::Union{NATS.Connection, Nothing} = nothing` - Pre-existing NATS connection. When provided, `smartsend` uses this connection instead of creating a new one, avoiding the overhead of connection establishment. This is useful for high-frequency publishing scenarios.
+
+**Connection Handling Logic:**
+```julia
+if is_publish == false
+  # skip publish
+elseif is_publish == true && NATS_connection === nothing
+  publish_message(broker_url, subject, env_json_str, cid)  # Creates new connection
+elseif is_publish == true && NATS_connection !== nothing
+  publish_message(NATS_connection, subject, env_json_str, cid)  # Uses provided connection
+end
+```
+
+**Example with pre-existing connection:**
+```julia
+using NATSBridge
+
+# Create connection once
+conn = NATS.connect("nats://localhost:4222")
+
+# Send multiple messages using the same connection
+for i in 1:100
+    data = rand(1000)
+    smartsend(
+        "analysis_results",
+        [("table_data", data, "table")],
+        NATS_connection=conn,  # Reuse connection
+        is_publish=true
+    )
+end
+
+# Close connection when done
+NATS.close(conn)
+```
+
+#### publish_message Function
+
+The `publish_message` function provides two overloads for publishing messages to NATS:
+
+**Overload 1 - URL-based publishing (creates new connection):**
+```julia
+function publish_message(broker_url::String, subject::String, message::String, correlation_id::String)
+  conn = NATS.connect(broker_url)  # Create NATS connection
+  publish_message(conn, subject, message, correlation_id)
+end
+```
+
+**Overload 2 - Connection-based publishing (uses pre-existing connection):**
+```julia
+function publish_message(conn::NATS.Connection, subject::String, message::String, correlation_id::String)
+  try
+    NATS.publish(conn, subject, message)  # Publish message to NATS
+    log_trace(correlation_id, "Message published to $subject")
+  finally
+    NATS.drain(conn)  # Ensure connection is closed properly
+  end
+end
+```
+
+**Use Case:** Use the connection-based overload when you already have an established NATS connection and want to publish multiple messages without the overhead of creating a new connection for each publish.
+
+**Integration with smartsend:**
+```julia
+# When NATS_connection is provided to smartsend, it uses the connection-based publish_message
+env, env_json_str = smartsend(
+    "my.subject",
+    [("data", payload_data, "type")],
+    NATS_connection=my_connection,  # Pre-existing connection
+    is_publish=true
+)
+# Uses: publish_message(NATS_connection, subject, env_json_str, cid)
+
+# When NATS_connection is not provided, it uses the URL-based publish_message
+env, env_json_str = smartsend(
+    "my.subject",
+    [("data", payload_data, "type")],
+    broker_url="nats://localhost:4222",
+    is_publish=true
+)
+# Uses: publish_message(broker_url, subject, env_json_str, cid)
+```
+
+**API Consistency Note:**
+- **Julia:** Uses `NATS_connection` keyword parameter with function overloading for automatic connection management
+- **JavaScript/Python:** Use `is_publish` option and achieve connection reuse by creating NATS client outside the function and reusing it in custom handlers or custom publish implementations
+
 #### JavaScript (Receiver)
 ```javascript
 const { smartreceive } = require('./src/NATSBridge');
@@ -482,19 +708,12 @@ const table = env.payloads;
 ```python
 from nats_bridge import smartsend
 
-# Binary data wrapped in a list
+# Binary data wrapped in list with type
-binary_data = [
-    ("audio_chunk", binary_buffer, "binary")
-]
-
 smartsend(
     "binary_input",
-    binary_data,
+    [("audio_chunk", binary_buffer, "binary")],
-    nats_url="nats://localhost:4222",
+    broker_url="nats://localhost:4222",
-    metadata={
+    metadata={"sample_rate": 44100, "channels": 1}
-        "sample_rate": 44100,
-        "channels": 1
-    }
 )
 ```
 
@@ -558,10 +777,14 @@ function process_binary(msg) {
 ```julia
 using NATSBridge
 
-function publish_health_status(nats_url)
+function publish_health_status(broker_url)
-    # Send status wrapped in a list (type is part of each tuple)
+    # Send status wrapped in list with type
     status = Dict("cpu" => rand(), "memory" => rand())
-    smartsend("health", [("status", status, "dictionary")], broker_url=nats_url)
+    env, env_json_str = smartsend(
+        "health",
+        [("status", status, "dictionary")],
+        broker_url=broker_url
+    )
     sleep(5)  # Every 5 seconds
 end
 ```
@@ -604,8 +827,8 @@ def handle_device_config(msg):
     env = smartreceive(msg)
     
     # Process configuration from payloads
-    for dataname, data, type in env["payloads"]:
+    for dataname, data, payload_type in env["payloads"]:
-        if type == "dictionary":
+        if payload_type == "dictionary":
             print(f"Received configuration: {data}")
             # Apply configuration to device
             if "wifi_ssid" in data:
@@ -622,7 +845,7 @@ def handle_device_config(msg):
     smartsend(
         "device/response",
         [("config", config, "dictionary")],
-        nats_url="nats://localhost:4222",
+        broker_url="nats://localhost:4222",
         reply_to=env.get("reply_to")
     )
 ```
@@ -670,12 +893,14 @@ options_df = DataFrame(
 # Check payload size (< 1MB threshold)
 # Publish directly to NATS with Base64-encoded payload
 # Include metadata for dashboard selection context
-smartsend(
+env, env_json_str = smartsend(
     "dashboard.selection",
     [("options_table", options_df, "table")],
-    nats_url="nats://localhost:4222",
+    broker_url="nats://localhost:4222",
     metadata=Dict("context" => "user_selection")
 )
+# env: msg_envelope_v1 with all metadata and payloads
+# env_json_str: JSON string for publishing
 ```
 
 **JavaScript (Receiver):**
@@ -709,7 +934,6 @@ await smartsend("dashboard.response", [
 **Julia (Sender/Receiver):**
 ```julia
 using NATSBridge
-using DataFrames
 
 # Build chat message with mixed payloads:
 # - Text: direct transport (Base64)
@@ -733,13 +957,15 @@ chat_message = [
     ("large_document", large_file_bytes, "binary")  # Large file, link transport
 ]
 
-smartsend(
+env, env_json_str = smartsend(
     "chat.room123",
     chat_message,
     broker_url="nats://localhost:4222",
     msg_purpose="chat",
     reply_to="chat.room123.responses"
 )
+# env: msg_envelope_v1 with all metadata and payloads
+# env_json_str: JSON string for publishing
 ```
 
 **JavaScript (Sender/Receiver):**

etc.jl

@@ -0,0 +1,9 @@
+Task: Update README.md to reflect recent changes in NATSbridge package.
+
+Context: the package has been updated with the NATS_connection keyword and the publish_message function.
+
+Requirements:
+
+Source of Truth: Treat the updated NATSbridge code as the definitive source. Update README.md to align exactly with these changes.
+API Consistency: Ensure the Main Package API (e.g., smartsend(), publish_message()) uses consistent naming across all three supported languages.
+Ecosystem Variance: Low-level native functions (e.g., NATS.connect(), JSON.read()) should follow the conventions of the specific language ecosystem and do not require cross-language consistency.

examples/tutorial.md

@@ -109,11 +109,11 @@ from nats_bridge import smartsend
 
 # Send a text message (is_publish=True by default)
 data = [("message", "Hello World", "text")]
-env, env_json_str = smartsend("/chat/room1", data, nats_url="nats://localhost:4222")
+env, env_json_str = smartsend("/chat/room1", data, broker_url="nats://localhost:4222")
 print("Message sent!")
 
 # Or use is_publish=False to get envelope and JSON without publishing
-env, env_json_str = smartsend("/chat/room1", data, nats_url="nats://localhost:4222", is_publish=False)
+env, env_json_str = smartsend("/chat/room1", data, broker_url="nats://localhost:4222", is_publish=False)
 # env: MessageEnvelope object
 # env_json_str: JSON string for publishing to NATS
 ```
@@ -126,14 +126,14 @@ const { smartsend } = require('./src/NATSBridge');
 // Send a text message (isPublish=true by default)
 await smartsend("/chat/room1", [
     { dataname: "message", data: "Hello World", type: "text" }
-], { natsUrl: "nats://localhost:4222" });
+], { brokerUrl: "nats://localhost:4222" });
 
 console.log("Message sent!");
 
 // Or use isPublish=false to get envelope and JSON without publishing
 const { env, env_json_str } = await smartsend("/chat/room1", [
     { dataname: "message", data: "Hello World", type: "text" }
-], { natsUrl: "nats://localhost:4222", isPublish: false });
+], { brokerUrl: "nats://localhost:4222", isPublish: false });
 // env: MessageEnvelope object
 // env_json_str: JSON string for publishing to NATS
 ```
@@ -145,8 +145,8 @@ using NATSBridge
 
 # Send a text message
 data = [("message", "Hello World", "text")]
-env, env_json_str = smartsend("/chat/room1", data, nats_url="nats://localhost:4222")
+env, env_json_str = smartsend("/chat/room1", data, broker_url="nats://localhost:4222")
-# env: msgEnvelope_v1 object with all metadata and payloads
+# env: msg_envelope_v1 object with all metadata and payloads
 # env_json_str: JSON string representation of the envelope for publishing
 println("Message sent!")
 ```
@@ -208,7 +208,7 @@ config = {
 
 # Send as dictionary type
 data = [("config", config, "dictionary")]
-env, env_json_str = smartsend("/device/config", data, nats_url="nats://localhost:4222")
+env, env_json_str = smartsend("/device/config", data, broker_url="nats://localhost:4222")
 ```
 
 #### JavaScript
@@ -224,7 +224,7 @@ const config = {
 
 const { env, env_json_str } = await smartsend("/device/config", [
     { dataname: "config", data: config, type: "dictionary" }
-]);
+], { brokerUrl: "nats://localhost:4222" });
 ```
 
 #### Julia
@@ -239,7 +239,7 @@ config = Dict(
 )
 
 data = [("config", config, "dictionary")]
-env, env_json_str = smartsend("/device/config", data)
+env, env_json_str = smartsend("/device/config", data, broker_url="nats://localhost:4222")
 ```
 
 ### Example 2: Sending Binary Data (Image)
@@ -255,7 +255,7 @@ with open("image.png", "rb") as f:
 
 # Send as binary type
 data = [("user_image", image_data, "binary")]
-env, env_json_str = smartsend("/chat/image", data, nats_url="nats://localhost:4222")
+env, env_json_str = smartsend("/chat/image", data, broker_url="nats://localhost:4222")
 ```
 
 #### JavaScript
@@ -269,7 +269,7 @@ const image_data = fs.readFileSync('image.png');
 
 const { env, env_json_str } = await smartsend("/chat/image", [
     { dataname: "user_image", data: image_data, type: "binary" }
-]);
+], { brokerUrl: "nats://localhost:4222" });
 ```
 
 #### Julia
@@ -281,7 +281,7 @@ using NATSBridge
 image_data = read("image.png")
 
 data = [("user_image", image_data, "binary")]
-env, env_json_str = smartsend("/chat/image", data)
+env, env_json_str = smartsend("/chat/image", data, broker_url="nats://localhost:4222")
 ```
 
 ### Example 3: Request-Response Pattern
@@ -296,11 +296,11 @@ data = [("command", {"action": "read_sensor"}, "dictionary")]
 env, env_json_str = smartsend(
     "/device/command",
     data,
-    nats_url="nats://localhost:4222",
+    broker_url="nats://localhost:4222",
     reply_to="/device/response",
     reply_to_msg_id="cmd-001"
 )
-# env: msgEnvelope_v1 object
+# env: MessageEnvelope object
 # env_json_str: JSON string for publishing to NATS
 ```
 
@@ -361,7 +361,7 @@ large_data = os.urandom(2_000_000)  # 2MB of random data
 env, env_json_str = smartsend(
     "/data/large",
     [("large_file", large_data, "binary")],
-    nats_url="nats://localhost:4222",
+    broker_url="nats://localhost:4222",
     fileserver_url="http://localhost:8080",
     size_threshold=1_000_000
 )
@@ -383,6 +383,7 @@ view.fill(42);  // Fill with some data
 const { env, env_json_str } = await smartsend("/data/large", [
     { dataname: "large_file", data: largeData, type: "binary" }
 ], {
+    brokerUrl: "nats://localhost:4222",
     fileserverUrl: "http://localhost:8080",
     sizeThreshold: 1_000_000
 });
@@ -399,6 +400,7 @@ large_data = rand(UInt8, 2_000_000)
 env, env_json_str = smartsend(
     "/data/large",
     [("large_file", large_data, "binary")],
+    broker_url="nats://localhost:4222",
     fileserver_url="http://localhost:8080"
 )
 
@@ -425,7 +427,7 @@ data = [
     ("user_avatar", image_data, "image")
 ]
 
-env, env_json_str = smartsend("/chat/mixed", data, nats_url="nats://localhost:4222")
+env, env_json_str = smartsend("/chat/mixed", data, broker_url="nats://localhost:4222")
 ```
 
 #### JavaScript
@@ -446,7 +448,7 @@ const { env, env_json_str } = await smartsend("/chat/mixed", [
         data: fs.readFileSync("avatar.png"),
         type: "image"
     }
-]);
+], { brokerUrl: "nats://localhost:4222" });
 ```
 
 #### Julia
@@ -461,7 +463,7 @@ data = [
     ("user_avatar", image_data, "image")
 ]
 
-env, env_json_str = smartsend("/chat/mixed", data)
+env, env_json_str = smartsend("/chat/mixed", data, broker_url="nats://localhost:4222")
 ```
 
 ### Example 6: Table Data (Arrow IPC)
@@ -483,7 +485,7 @@ df = pd.DataFrame({
 
 # Send as table type
 data = [("students", df, "table")]
-env, env_json_str = smartsend("/data/students", data, nats_url="nats://localhost:4222")
+env, env_json_str = smartsend("/data/students", data, broker_url="nats://localhost:4222")
 ```
 
 #### Julia
@@ -500,7 +502,7 @@ df = DataFrame(
 )
 
 data = [("students", df, "table")]
-env, env_json_str = smartsend("/data/students", data)
+env, env_json_str = smartsend("/data/students", data, broker_url="nats://localhost:4222")
 ```
 
 ---
@@ -519,7 +521,7 @@ using NATSBridge
 # Send dictionary from Julia to JavaScript
 config = Dict("step_size" => 0.01, "iterations" => 1000)
 data = [("config", config, "dictionary")]
-env, env_json_str = smartsend("/analysis/config", data, nats_url="nats://localhost:4222")
+env, env_json_str = smartsend("/analysis/config", data, broker_url="nats://localhost:4222")
 ```
 
 #### JavaScript Receiver
@@ -546,7 +548,7 @@ const { smartsend } = require('./src/NATSBridge');
 
 const { env, env_json_str } = await smartsend("/data/transfer", [
     { dataname: "message", data: "Hello from JS!", type: "text" }
-]);
+], { brokerUrl: "nats://localhost:4222" });
 ```
 
 #### Python Receiver
@@ -568,7 +570,7 @@ for dataname, data, type in env["payloads"]:
 from nats_bridge import smartsend
 
 data = [("message", "Hello from Python!", "text")]
-env, env_json_str = smartsend("/chat/python", data)
+env, env_json_str = smartsend("/chat/python", data, broker_url="nats://localhost:4222")
 ```
 
 #### Julia Receiver
@@ -576,7 +578,7 @@ env, env_json_str = smartsend("/chat/python", data)
 ```julia
 using NATSBridge
 
-env = smartreceive(msg, fileserverDownloadHandler)
+env = smartreceive(msg; fileserver_download_handler=_fetch_with_backoff)
 for (dataname, data, type) in env["payloads"]
     if type == "text"
         println("Received from Python: $data")

examples/walkthrough.md

@@ -136,6 +136,7 @@ class ChatUI {
             `/chat/${this.currentRoom}`,
             data,
             {
+                brokerUrl: window.config.broker_url,
                 fileserverUrl: window.config.fileserver_url,
                 sizeThreshold: window.config.size_threshold
             }
@@ -288,8 +289,8 @@ Let's build a file transfer system that handles large files efficiently.
 const { smartsend } = require('./NATSBridge');
 
 class FileUploadService {
-    constructor(natsUrl, fileserverUrl) {
+    constructor(brokerUrl, fileserverUrl) {
-        this.natsUrl = natsUrl;
+        this.brokerUrl = brokerUrl;
         this.fileserverUrl = fileserverUrl;
     }
     
@@ -308,7 +309,7 @@ class FileUploadService {
             `/files/${recipient}`,
             data,
             {
-                natsUrl: this.natsUrl,
+                brokerUrl: this.brokerUrl,
                 fileserverUrl: this.fileserverUrl,
                 sizeThreshold: 1048576
             }
@@ -419,7 +420,7 @@ async function uploadFile(config) {
     const filePath = await rl.question('Enter file path: ');
     const recipient = await rl.question('Enter recipient: ');
     
-    const fileService = new FileUploadService(config.nats_url, config.fileserver_url);
+    const fileService = new FileUploadService(config.broker_url, config.fileserver_url);
     
     try {
         const env = await fileService.uploadFile(filePath, recipient);
@@ -500,8 +501,8 @@ import time
 import random
 
 class SensorSender:
-    def __init__(self, nats_url: str, fileserver_url: str):
+    def __init__(self, broker_url: str, fileserver_url: str):
-        self.nats_url = nats_url
+        self.broker_url = broker_url
         self.fileserver_url = fileserver_url
         
     def send_reading(self, sensor_id: str, value: float, unit: str):
@@ -518,7 +519,7 @@ class SensorSender:
         smartsend(
             f"/sensors/{sensor_id}",
             data,
-            nats_url=self.nats_url,
+            broker_url=self.broker_url,
             fileserver_url=self.fileserver_url
         )
         
@@ -537,7 +538,7 @@ class SensorSender:
         env, env_json_str = smartsend(
             f"/sensors/{sensor_id}/prepare",
             data,
-            nats_url=self.nats_url,
+            broker_url=self.broker_url,
             fileserver_url=self.fileserver_url,
             is_publish=False
         )
@@ -572,7 +573,7 @@ class SensorSender:
             smartsend(
                 f"/sensors/batch",
                 data,
-                nats_url=self.nats_url,
+                broker_url=self.broker_url,
                 fileserver_url=self.fileserver_url
             )
         else:
@@ -631,17 +632,17 @@ Let's build an IoT device using Micropython that connects to NATS.
 import json
 
 class DeviceConfig:
-    def __init__(self, ssid, password, nats_url, device_id):
+    def __init__(self, ssid, password, broker_url, device_id):
         self.ssid = ssid
         self.password = password
-        self.nats_url = nats_url
+        self.broker_url = broker_url
         self.device_id = device_id
         
     def to_dict(self):
         return {
             "ssid": self.ssid,
             "password": self.password,
-            "nats_url": self.nats_url,
+            "broker_url": self.broker_url,
             "device_id": self.device_id
         }
 ```
@@ -656,7 +657,7 @@ import json
 class DeviceBridge:
     def __init__(self, config):
         self.config = config
-        self.nats_url = config.nats_url
+        self.broker_url = config.broker_url
         
     def connect(self):
         # Connect to WiFi
@@ -676,7 +677,7 @@ class DeviceBridge:
         smartsend(
             f"/devices/{self.config.device_id}/status",
             data,
-            nats_url=self.nats_url
+            broker_url=self.broker_url
         )
         
     def send_sensor_data(self, sensor_id, value, unit):
@@ -687,7 +688,7 @@ class DeviceBridge:
         smartsend(
             f"/devices/{self.config.device_id}/sensors/{sensor_id}",
             data,
-            nats_url=self.nats_url
+            broker_url=self.broker_url
         )
         
     def receive_commands(self, callback):
@@ -725,7 +726,7 @@ import random
 config = DeviceConfig(
     ssid="MyNetwork",
     password="password123",
-    nats_url="nats://localhost:4222",
+    broker_url="nats://localhost:4222",
     device_id="device-001"
 )
 
@@ -774,8 +775,8 @@ import pyarrow as pa
 import io
 
 class DashboardServer:
-    def __init__(self, nats_url, fileserver_url):
+    def __init__(self, broker_url, fileserver_url):
-        self.nats_url = nats_url
+        self.broker_url = broker_url
         self.fileserver_url = fileserver_url
         
     def broadcast_data(self, df):
@@ -792,7 +793,7 @@ class DashboardServer:
         smartsend(
             "/dashboard/data",
             data,
-            nats_url=self.nats_url,
+            broker_url=self.broker_url,
             fileserver_url=self.fileserver_url
         )
         
@@ -836,6 +837,7 @@ class DashboardUI {
         const { env, env_json_str } = await smartsend("/dashboard/request", [
             { dataname: "request", data: { type: "refresh" }, type: "dictionary" }
         ], {
+            brokerUrl: window.config.broker_url,
             fileserverUrl: window.config.fileserver_url
         });
     }
@@ -954,7 +956,7 @@ def send_batch_readings(self, readings):
     smartsend(
         "/sensors/batch",
         [("batch", arrow_data, "table")],
-        nats_url=self.nats_url
+        broker_url=self.broker_url
     )
 ```
 

src/NATSBridge.jl

@@ -383,6 +383,7 @@ Each payload can have a different type, enabling mixed-content messages (e.g., c
    - `reply_to::String = ""` - Topic to reply to (empty string if no reply expected)
    - `reply_to_msg_id::String = ""` - Message ID this message is replying to
    - `is_publish::Bool = true` - Whether to automatically publish the message to NATS
+   - `NATS_connection::Union{NATS.Connection, Nothing} = nothing` - Pre-existing NATS connection (if provided, uses this connection instead of creating a new one; saves connection establishment overhead)
 
 # Return:
   - A tuple `(env, env_json_str)` where:
@@ -431,12 +432,12 @@ function smartsend(
   receiver_id::String = "",
   reply_to::String = "",
   reply_to_msg_id::String = "",
-  is_publish::Bool = true   # some time the user want to get env and env_json_str from this function without publishing the msg
+  is_publish::Bool = true,   # some time the user want to get env and env_json_str from this function without publishing the msg
+  NATS_connection::Union{NATS.Connection, Nothing} = nothing  # a provided connection saves establishing connection overhead.
 ) where {T1<:Any}
 
   # Generate correlation ID if not provided
   cid = correlation_id !== nothing ? correlation_id : string(uuid4())  # Create or use provided correlation ID
-  
   log_trace(cid, "Starting smartsend for subject: $subject")  # Log start of send operation
   
   # Generate message metadata
@@ -516,8 +517,12 @@ function smartsend(
   )
   
   env_json_str = envelope_to_json(env)  # Convert envelope to JSON
-  if is_publish
+  if is_publish == false
+    # skip publish a message
+  elseif is_publish == true && NATS_connection === nothing
     publish_message(broker_url, subject, env_json_str, cid)  # Publish message to NATS
+  elseif is_publish == true && NATS_connection !== nothing
+    publish_message(NATS_connection, subject, env_json_str, cid)  # Publish message to NATS
   end
   
   return (env, env_json_str)
@@ -649,7 +654,7 @@ end
 
 
 """ publish_message - Publish message to NATS
-This internal function publishes a message to a NATS subject with proper
+This function publishes a message to a NATS subject with proper
 connection management and logging.
 
 # Arguments:
@@ -674,6 +679,40 @@ connection management and logging.
 """
 function publish_message(broker_url::String, subject::String, message::String, correlation_id::String)
   conn = NATS.connect(broker_url)  # Create NATS connection
+  publish_message(conn, subject, message, correlation_id)
+end
+
+""" publish_message - Publish message to NATS using pre-existing connection
+This function publishes a message to a NATS subject using a pre-existing NATS connection,
+avoiding the overhead of connection establishment.
+
+# Arguments:
+  - `conn::NATS.Connection` - Pre-existing NATS connection
+  - `subject::String` - NATS subject to publish to (e.g., "/agent/wine/api/v1/prompt")
+  - `message::String` - JSON message to publish
+  - `correlation_id::String` - Correlation ID for tracing and logging
+
+# Return:
+  - `nothing` - This function performs publishing but returns nothing
+
+# Example
+```jldoctest
+using NATS
+
+# Prepare JSON message
+message = "{\"correlation_id\":\"abc123\",\"payload\":\"test\"}"
+
+# Create connection once and reuse for multiple publishes
+conn = NATS.connect("nats://localhost:4222")
+publish_message(conn, "my.subject", message, "abc123")
+# Connection is automatically drained after publish
+```
+
+# Use Case:
+Use this version when you already have an established NATS connection and want to publish
+multiple messages without the overhead of creating a new connection for each publish.
+"""
+function publish_message(conn::NATS.Connection, subject::String, message::String, correlation_id::String)
   try
     NATS.publish(conn, subject, message)  # Publish message to NATS
     log_trace(correlation_id, "Message published to $subject")  # Log successful publish
@@ -706,7 +745,7 @@ A HTTP file server is required along with its download function.
   - `max_delay::Int = 5000` - Maximum delay for exponential backoff in ms
 
 # Return:
-   - `Vector{Tuple{String, Any, String}}` - List of (dataname, data, type) tuples
+   - JSON object of envelope with list of (dataname, data, data_type) tuples in payloads field
 
 # Example
 ```jldoctest
@@ -724,22 +763,22 @@ function smartreceive(
   max_delay::Int = 5000
 )
   # Parse the JSON envelope
-  json_data = JSON.parse(String(msg.payload))
+  env_json_obj = JSON.parse(String(msg.payload))
-  log_trace(json_data["correlation_id"], "Processing received message")  # Log message processing start
+  log_trace(env_json_obj["correlation_id"], "Processing received message")  # Log message processing start
   
   # Process all payloads in the envelope
   payloads_list = Tuple{String, Any, String}[]
   
   # Get number of payloads
-  num_payloads = length(json_data["payloads"])
+  num_payloads = length(env_json_obj["payloads"])
     
   for i in 1:num_payloads
-    payload = json_data["payloads"][i]
+    payload = env_json_obj["payloads"][i]
     transport = String(payload["transport"])
     dataname = String(payload["dataname"])
     
     if transport == "direct"  # Direct transport - payload is in the message
-      log_trace(json_data["correlation_id"], "Direct transport - decoding payload '$dataname'")  # Log direct transport handling
+      log_trace(env_json_obj["correlation_id"], "Direct transport - decoding payload '$dataname'")  # Log direct transport handling
       
       # Extract base64 payload from the payload
       payload_b64 = String(payload["data"])
@@ -749,28 +788,28 @@ function smartreceive(
       
       # Deserialize based on type
       data_type = String(payload["payload_type"])
-        data = _deserialize_data(payload_bytes, data_type, json_data["correlation_id"])
+        data = _deserialize_data(payload_bytes, data_type, env_json_obj["correlation_id"])
       
       push!(payloads_list, (dataname, data, data_type))
     elseif transport == "link"  # Link transport - payload is at URL
       # Extract download URL from the payload
       url = String(payload["data"])
-        log_trace(json_data["correlation_id"], "Link transport - fetching '$dataname' from URL: $url")  # Log link transport handling
+        log_trace(env_json_obj["correlation_id"], "Link transport - fetching '$dataname' from URL: $url")  # Log link transport handling
       
       # Fetch with exponential backoff using the download handler
-        downloaded_data = fileserver_download_handler(url, max_retries, base_delay, max_delay, json_data["correlation_id"])
+        downloaded_data = fileserver_download_handler(url, max_retries, base_delay, max_delay, env_json_obj["correlation_id"])
 
       # Deserialize based on type
       data_type = String(payload["payload_type"])
-        data = _deserialize_data(downloaded_data, data_type, json_data["correlation_id"])
+        data = _deserialize_data(downloaded_data, data_type, env_json_obj["correlation_id"])
       
       push!(payloads_list, (dataname, data, data_type))
     else  # Unknown transport type
       error("Unknown transport type for payload '$dataname': $(transport)")  # Throw error for unknown transport
     end
   end
-  json_data["payloads"] = payloads_list
+  env_json_obj["payloads"] = payloads_list
-  return json_data  # Return envelope with list of (dataname, data, data_type) tuples in payloads field
+  return env_json_obj  # JSON object of envelope with list of (dataname, data, data_type) tuples in payloads field
 end
 
 
@@ -915,7 +954,7 @@ retrieves an upload ID and token, then uploads the file data as multipart form d
 
 # Arguments:
    - `file_server_url::String` - Base URL of the plik server (e.g., `"http://localhost:8080"`)
-   - `filename::String` - Name of the file being uploaded
+   - `dataname::String` - Name of the file being uploaded
    - `data::Vector{UInt8}` - Raw byte data of the file content
 
 # Return:
@@ -929,18 +968,18 @@ retrieves an upload ID and token, then uploads the file data as multipart form d
  ```jldoctest
  using HTTP, JSON
 
- file_server_url = "http://localhost:8080"
+ fileserver_url = "http://localhost:8080"
- filename = "test.txt"
+ dataname = "test.txt"
  data = Vector{UInt8}("hello world")
 
  # Upload to local plik server
- result = plik_oneshot_upload(file_server_url, filename, data)
+ result = plik_oneshot_upload(file_server_url, dataname, data)
 
  # Access the result as a Dict
  # result["status"], result["uploadid"], result["fileid"], result["url"]
  ```
 """
-function plik_oneshot_upload(file_server_url::String, filename::String, data::Vector{UInt8})
+function plik_oneshot_upload(file_server_url::String, dataname::String, data::Vector{UInt8})
 
   # ----------------------------------------- get upload id ---------------------------------------- #
   # Equivalent curl command:  curl -X POST -d '{ "OneShot" : true }' http://localhost:8080/upload
@@ -954,7 +993,7 @@ function plik_oneshot_upload(file_server_url::String, filename::String, data::Ve
 
   # ------------------------------------------ upload file ----------------------------------------- #
   # Equivalent curl command:  curl -X POST --header "X-UploadToken: UPLOAD_TOKEN" -F "file=@PATH_TO_FILE" http://localhost:8080/file/UPLOAD_ID
-  file_multipart = HTTP.Multipart(filename, IOBuffer(data), "application/octet-stream") # Plik won't accept raw bytes upload
+  file_multipart = HTTP.Multipart(dataname, IOBuffer(data), "application/octet-stream") # Plik won't accept raw bytes upload
   url_upload = "$file_server_url/file/$uploadid"
   headers = ["X-UploadToken" => uploadtoken]
 
@@ -974,7 +1013,7 @@ function plik_oneshot_upload(file_server_url::String, filename::String, data::Ve
   fileid = response_json["id"]
 
   # url of the uploaded data e.g. "http://192.168.1.20:8080/file/3F62E/4AgGT/test.zip"
-  url = "$file_server_url/file/$uploadid/$fileid/$filename"
+  url = "$file_server_url/file/$uploadid/$fileid/$dataname"
 
   return Dict("status" => http_response.status, "uploadid" => uploadid, "fileid" => fileid, "url" => url)
 end
@@ -1006,7 +1045,7 @@ retrieves an upload ID and token, then uploads the file data as multipart form d
 ```jldoctest
 using HTTP, JSON
 
-file_server_url = "http://localhost:8080"
+fileserver_url = "http://localhost:8080"
 filepath = "./test.zip"
 
 # Upload to local plik server
@@ -1056,7 +1095,7 @@ function plik_oneshot_upload(file_server_url::String, filepath::String)
 end
 
 function _get_payload_bytes(data)
-  @error "didn't implement yet"
+  @error "Didn't implement yet. The developer will implement this function later."
 end
 
 

src/NATSBridge.js

@@ -17,7 +17,7 @@
  * // The handler is passed to smartsend as fileserverUploadHandler parameter
  * // It receives: (fileserver_url, dataname, data)
  * // Returns: { status, uploadid, fileid, url }
- * async function fileserverUploadHandler(fileserver_url, dataname, data) { ... }
+ * async function plik_oneshot_upload(fileserver_url, dataname, data) { ... }
  *
  * // Download handler - fetches data from file server URL with exponential backoff
  * // The handler is passed to smartreceive as fileserverDownloadHandler parameter
@@ -98,6 +98,26 @@ function base64ToArrayBuffer(base64) {
     return bytes.buffer;
 }
 
+// Helper: Convert Uint8Array to Base64 string
+function uint8ArrayToBase64(uint8array) {
+    let binary = '';
+    for (let i = 0; i < uint8array.byteLength; i++) {
+        binary += String.fromCharCode(uint8array[i]);
+    }
+    return btoa(binary);
+}
+
+// Helper: Convert Base64 string to Uint8Array
+function base64ToUint8Array(base64) {
+    const binaryString = atob(base64);
+    const len = binaryString.length;
+    const bytes = new Uint8Array(len);
+    for (let i = 0; i < len; i++) {
+        bytes[i] = binaryString.charCodeAt(i);
+    }
+    return bytes;
+}
+
 // Helper: Serialize data based on type
 function _serialize_data(data, type) {
     /**
@@ -114,39 +134,39 @@ function _serialize_data(data, type) {
      */
     if (type === "text") {
         if (typeof data === 'string') {
-            return new TextEncoder().encode(data).buffer;
+            return new TextEncoder().encode(data);
         } else {
             throw new Error("Text data must be a String");
         }
     } else if (type === "dictionary") {
         // JSON data - serialize directly
         const jsonStr = JSON.stringify(data);
-        return new TextEncoder().encode(jsonStr).buffer;
+        return new TextEncoder().encode(jsonStr);
     } else if (type === "table") {
         // Table data - convert to Arrow IPC stream (NOT IMPLEMENTED in pure JavaScript)
         // This would require the apache-arrow library
         throw new Error("Table serialization requires apache-arrow library");
     } else if (type === "image") {
         if (data instanceof ArrayBuffer || data instanceof Uint8Array) {
-            return data instanceof ArrayBuffer ? data : data.buffer;
+            return data instanceof ArrayBuffer ? new Uint8Array(data) : data;
         } else {
             throw new Error("Image data must be ArrayBuffer or Uint8Array");
         }
     } else if (type === "audio") {
         if (data instanceof ArrayBuffer || data instanceof Uint8Array) {
-            return data instanceof ArrayBuffer ? data : data.buffer;
+            return data instanceof ArrayBuffer ? new Uint8Array(data) : data;
         } else {
             throw new Error("Audio data must be ArrayBuffer or Uint8Array");
         }
     } else if (type === "video") {
         if (data instanceof ArrayBuffer || data instanceof Uint8Array) {
-            return data instanceof ArrayBuffer ? data : data.buffer;
+            return data instanceof ArrayBuffer ? new Uint8Array(data) : data;
         } else {
             throw new Error("Video data must be ArrayBuffer or Uint8Array");
         }
     } else if (type === "binary") {
         if (data instanceof ArrayBuffer || data instanceof Uint8Array) {
-            return data instanceof ArrayBuffer ? data : data.buffer;
+            return data instanceof ArrayBuffer ? new Uint8Array(data) : data;
         } else {
             throw new Error("Binary data must be ArrayBuffer or Uint8Array");
         }
@@ -171,10 +191,10 @@ function _deserialize_data(data, type, correlation_id) {
      */
     if (type === "text") {
         const decoder = new TextDecoder();
-        return decoder.decode(new Uint8Array(data));
+        return decoder.decode(data);
     } else if (type === "dictionary") {
         const decoder = new TextDecoder();
-        const jsonStr = decoder.decode(new Uint8Array(data));
+        const jsonStr = decoder.decode(data);
         return JSON.parse(jsonStr);
     } else if (type === "table") {
         // Table data - deserialize Arrow IPC stream (NOT IMPLEMENTED in pure JavaScript)
@@ -193,73 +213,16 @@ function _deserialize_data(data, type, correlation_id) {
 }
 
 // Helper: Upload data to file server
+// Internal wrapper that adds correlation_id logging for smartsend
 async function _upload_to_fileserver(fileserver_url, dataname, data, correlation_id) {
     /**
-     * Upload data to HTTP file server (plik-like API)
+     * Internal upload helper - wraps plik_oneshot_upload to add correlation_id logging
-     * 
+     * This allows smartsend to pass correlation_id for tracing without changing the handler signature
-     * This function implements the plik one-shot upload mode:
-     * 1. Creates a one-shot upload session by sending POST request with {"OneShot": true}
-     * 2. Uploads the file data as multipart form data
-     * 3. Returns identifiers and download URL for the uploaded file
      */
     log_trace(correlation_id, `Uploading ${dataname} to fileserver: ${fileserver_url}`);
-    
+    const result = await plik_oneshot_upload(fileserver_url, dataname, data);
-    // Step 1: Get upload ID and token
+    log_trace(correlation_id, `Uploaded to URL: ${result.url}`);
-    const url_getUploadID = `${fileserver_url}/upload`;
+    return result;
-    const headers = {
-        "Content-Type": "application/json"
-    };
-    const body = JSON.stringify({ OneShot: true });
-    
-    let response = await fetch(url_getUploadID, {
-        method: "POST",
-        headers: headers,
-        body: body
-    });
-    
-    if (!response.ok) {
-        throw new Error(`Failed to get upload ID: ${response.status} ${response.statusText}`);
-    }
-    
-    const responseJson = await response.json();
-    const uploadid = responseJson.id;
-    const uploadtoken = responseJson.uploadToken;
-    
-    // Step 2: Upload file data
-    const url_upload = `${fileserver_url}/file/${uploadid}`;
-    
-    // Create multipart form data
-    const formData = new FormData();
-    // Create a Blob from the ArrayBuffer
-    const blob = new Blob([data], { type: "application/octet-stream" });
-    formData.append("file", blob, dataname);
-    
-    response = await fetch(url_upload, {
-        method: "POST",
-        headers: {
-            "X-UploadToken": uploadtoken
-        },
-        body: formData
-    });
-    
-    if (!response.ok) {
-        throw new Error(`Failed to upload file: ${response.status} ${response.statusText}`);
-    }
-    
-    const fileResponseJson = await response.json();
-    const fileid = fileResponseJson.id;
-    
-    // Build the download URL
-    const url = `${fileserver_url}/file/${uploadid}/${fileid}/${encodeURIComponent(dataname)}`;
-    
-    log_trace(correlation_id, `Uploaded to URL: ${url}`);
-    
-    return {
-        status: response.status,
-        uploadid: uploadid,
-        fileid: fileid,
-        url: url
-    };
 }
 
 // Helper: Fetch data from URL with exponential backoff
@@ -276,7 +239,7 @@ async function _fetch_with_backoff(url, max_retries, base_delay, max_delay, corr
             if (response.status === 200) {
                 log_trace(correlation_id, `Successfully fetched data from ${url} on attempt ${attempt}`);
                 const arrayBuffer = await response.arrayBuffer();
-                return arrayBuffer;
+                return new Uint8Array(arrayBuffer);
             } else {
                 throw new Error(`Failed to fetch: ${response.status} ${response.statusText}`);
             }
@@ -306,25 +269,26 @@ function _get_payload_bytes(data) {
     }
 }
 
-// MessagePayload class
+// MessagePayload class - matches msg_payload_v1 Julia struct
 class MessagePayload {
     /**
      * Represents a single payload in the message envelope
+     * Matches Julia's msg_payload_v1 struct
      * 
      * @param {Object} options - Payload options
      * @param {string} options.id - ID of this payload (e.g., "uuid4")
      * @param {string} options.dataname - Name of this payload (e.g., "login_image")
-     * @param {string} options.type - Payload type: "text", "dictionary", "table", "image", "audio", "video", "binary"
+     * @param {string} options.payload_type - Payload type: "text", "dictionary", "table", "image", "audio", "video", "binary"
      * @param {string} options.transport - "direct" or "link"
      * @param {string} options.encoding - "none", "json", "base64", "arrow-ipc"
      * @param {number} options.size - Data size in bytes
-     * @param {string|ArrayBuffer} options.data - Payload data (direct) or URL (link)
+     * @param {string|Uint8Array} options.data - Payload data (Uint8Array for direct, URL string for link)
      * @param {Object} options.metadata - Metadata for this payload
      */
     constructor(options) {
         this.id = options.id || uuid4();
         this.dataname = options.dataname;
-        this.type = options.type;
+        this.payload_type = options.payload_type;
         this.transport = options.transport;
         this.encoding = options.encoding;
         this.size = options.size;
@@ -332,27 +296,27 @@ class MessagePayload {
         this.metadata = options.metadata || {};
     }
     
-    // Convert to JSON object
+    // Convert to JSON object - uses snake_case to match Julia API
     toJSON() {
         const obj = {
             id: this.id,
             dataname: this.dataname,
-            type: this.type,
+            payload_type: this.payload_type,
             transport: this.transport,
             encoding: this.encoding,
             size: this.size
         };
         
         // Include data based on transport type
-        if (this.transport === "direct" && this.data !== null) {
+        if (this.transport === "direct" && this.data !== null && this.data !== undefined) {
             if (this.encoding === "base64" || this.encoding === "json") {
                 obj.data = this.data;
             } else {
                 // For other encodings, use base64
                 const payloadBytes = _get_payload_bytes(this.data);
-                obj.data = arrayBufferToBase64(payloadBytes);
+                obj.data = uint8ArrayToBase64(payloadBytes);
             }
-        } else if (this.transport === "link" && this.data !== null) {
+        } else if (this.transport === "link" && this.data !== null && this.data !== undefined) {
             // For link transport, data is a URL string
             obj.data = this.data;
         }
@@ -365,59 +329,60 @@ class MessagePayload {
     }
 }
 
-// MessageEnvelope class
+// MessageEnvelope class - matches msg_envelope_v1 Julia struct
 class MessageEnvelope {
     /**
      * Represents the message envelope containing metadata and payloads
+     * Matches Julia's msg_envelope_v1 struct
      * 
      * @param {Object} options - Envelope options
-     * @param {string} options.sendTo - Topic/subject the sender sends to
+     * @param {string} options.correlation_id - Unique identifier to track messages
-     * @param {Array<MessagePayload>} options.payloads - Array of payloads
+     * @param {string} options.msg_id - This message id
-     * @param {string} options.correlationId - Unique identifier to track messages
-     * @param {string} options.msgId - This message id
      * @param {string} options.timestamp - Message published timestamp
-     * @param {string} options.msgPurpose - Purpose of this message
+     * @param {string} options.send_to - Topic/subject the sender sends to
-     * @param {string} options.senderName - Name of the sender
+     * @param {string} options.msg_purpose - Purpose of this message
-     * @param {string} options.senderId - UUID of the sender
+     * @param {string} options.sender_name - Name of the sender
-     * @param {string} options.receiverName - Name of the receiver
+     * @param {string} options.sender_id - UUID of the sender
-     * @param {string} options.receiverId - UUID of the receiver
+     * @param {string} options.receiver_name - Name of the receiver
-     * @param {string} options.replyTo - Topic to reply to
+     * @param {string} options.receiver_id - UUID of the receiver
-     * @param {string} options.replyToMsgId - Message id this message is replying to
+     * @param {string} options.reply_to - Topic to reply to
-     * @param {string} options.brokerURL - NATS server address
+     * @param {string} options.reply_to_msg_id - Message id this message is replying to
+     * @param {string} options.broker_url - NATS server address
      * @param {Object} options.metadata - Metadata for the envelope
+     * @param {Array<MessagePayload>} options.payloads - Array of payloads
      */
     constructor(options) {
-        this.correlationId = options.correlationId || uuid4();
+        this.correlation_id = options.correlation_id || uuid4();
-        this.msgId = options.msgId || uuid4();
+        this.msg_id = options.msg_id || uuid4();
         this.timestamp = options.timestamp || new Date().toISOString();
-        this.sendTo = options.sendTo;
+        this.send_to = options.send_to;
-        this.msgPurpose = options.msgPurpose || "";
+        this.msg_purpose = options.msg_purpose || "";
-        this.senderName = options.senderName || "";
+        this.sender_name = options.sender_name || "";
-        this.senderId = options.senderId || uuid4();
+        this.sender_id = options.sender_id || uuid4();
-        this.receiverName = options.receiverName || "";
+        this.receiver_name = options.receiver_name || "";
-        this.receiverId = options.receiverId || "";
+        this.receiver_id = options.receiver_id || "";
-        this.replyTo = options.replyTo || "";
+        this.reply_to = options.reply_to || "";
-        this.replyToMsgId = options.replyToMsgId || "";
+        this.reply_to_msg_id = options.reply_to_msg_id || "";
-        this.brokerURL = options.brokerURL || DEFAULT_NATS_URL;
+        this.broker_url = options.broker_url || DEFAULT_NATS_URL;
         this.metadata = options.metadata || {};
         this.payloads = options.payloads || [];
     }
     
-    // Convert to JSON string
+    // Convert to JSON object - uses snake_case to match Julia API
     toJSON() {
         const obj = {
-            correlationId: this.correlationId,
+            correlation_id: this.correlation_id,
-            msgId: this.msgId,
+            msg_id: this.msg_id,
             timestamp: this.timestamp,
-            sendTo: this.sendTo,
+            send_to: this.send_to,
-            msgPurpose: this.msgPurpose,
+            msg_purpose: this.msg_purpose,
-            senderName: this.senderName,
+            sender_name: this.sender_name,
-            senderId: this.senderId,
+            sender_id: this.sender_id,
-            receiverName: this.receiverName,
+            receiver_name: this.receiver_name,
-            receiverId: this.receiverId,
+            receiver_id: this.receiver_id,
-            replyTo: this.replyTo,
+            reply_to: this.reply_to,
-            replyToMsgId: this.replyToMsgId,
+            reply_to_msg_id: this.reply_to_msg_id,
-            brokerURL: this.brokerURL
+            broker_url: this.broker_url
         };
         
         if (Object.keys(this.metadata).length > 0) {
@@ -437,7 +402,7 @@ class MessageEnvelope {
     }
 }
 
-// SmartSend function
+// SmartSend function - matches Julia smartsend signature and behavior
 async function smartsend(subject, data, options = {}) {
     /**
      * Send data either directly via NATS or via a fileserver URL, depending on payload size
@@ -447,42 +412,45 @@ async function smartsend(subject, data, options = {}) {
      * Otherwise, it uploads the data to a fileserver and publishes only the download URL over NATS.
      * 
      * @param {string} subject - NATS subject to publish the message to
-     * @param {Array} data - List of {dataname, data, type} objects to send
+     * @param {Array} data - List of {dataname, data, type} objects to send (must be a list, even for single payload)
      * @param {Object} options - Additional options
-     * @param {string} options.natsUrl - URL of the NATS server (default: "nats://localhost:4222")
+     * @param {string} options.broker_url - URL of the NATS server (default: "nats://localhost:4222")
-     * @param {string} options.fileserverUrl - Base URL of the file server (default: "http://localhost:8080")
+     * @param {string} options.fileserver_url - Base URL of the file server (default: "http://localhost:8080")
-     * @param {Function} options.fileserverUploadHandler - Function to handle fileserver uploads
+     * @param {Function} options.fileserver_upload_handler - Function to handle fileserver uploads
-     * @param {number} options.sizeThreshold - Threshold in bytes separating direct vs link transport (default: 1MB)
+     * @param {number} options.size_threshold - Threshold in bytes separating direct vs link transport (default: 1MB)
-     * @param {string} options.correlationId - Optional correlation ID for tracing
+     * @param {string} options.correlation_id - Optional correlation ID for tracing
-     * @param {string} options.msgPurpose - Purpose of the message (default: "chat")
+     * @param {string} options.msg_purpose - Purpose of the message (default: "chat")
-     * @param {string} options.senderName - Name of the sender (default: "NATSBridge")
+     * @param {string} options.sender_name - Name of the sender (default: "NATSBridge")
-     * @param {string} options.receiverName - Name of the receiver (default: "")
+     * @param {string} options.receiver_name - Name of the receiver (default: "")
-     * @param {string} options.receiverId - UUID of the receiver (default: "")
+     * @param {string} options.receiver_id - UUID of the receiver (default: "")
-     * @param {string} options.replyTo - Topic to reply to (default: "")
+     * @param {string} options.reply_to - Topic to reply to (default: "")
-     * @param {string} options.replyToMsgId - Message ID this message is replying to (default: "")
+ * @param {string} options.reply_to_msg_id - Message ID this message is replying to (default: "")
-     * @param {boolean} options.isPublish - Whether to automatically publish the message to NATS (default: true)
+ * @param {boolean} options.is_publish - Whether to automatically publish the message to NATS (default: true)
-     * 
+ *   - When true: Message is published to NATS automatically
-     * @returns {Promise<Object>} - An object with { env: MessageEnvelope, env_json_str: string }
+ *   - When false: Returns (env, env_json_str) without publishing, allowing manual publishing
+ * @returns {Promise<Object>} - A tuple-like object with { env: MessageEnvelope, env_json_str: string }
+ *   - env: MessageEnvelope object with all metadata and payloads
+ *   - env_json_str: JSON string representation of the envelope for manual publishing
  */
     const {
-        natsUrl = DEFAULT_NATS_URL,
+        broker_url = DEFAULT_NATS_URL,
-        fileserverUrl = DEFAULT_FILESERVER_URL,
+        fileserver_url = DEFAULT_FILESERVER_URL,
-        fileserverUploadHandler = _upload_to_fileserver,
+        fileserver_upload_handler = _upload_to_fileserver,
-        sizeThreshold = DEFAULT_SIZE_THRESHOLD,
+        size_threshold = DEFAULT_SIZE_THRESHOLD,
-        correlationId = uuid4(),
+        correlation_id = uuid4(),
-        msgPurpose = "chat",
+        msg_purpose = "chat",
-        senderName = "NATSBridge",
+        sender_name = "NATSBridge",
-        receiverName = "",
+        receiver_name = "",
-        receiverId = "",
+        receiver_id = "",
-        replyTo = "",
+        reply_to = "",
-        replyToMsgId = "",
+        reply_to_msg_id = "",
-        isPublish = true  // Whether to automatically publish the message to NATS
+        is_publish = true  // Whether to automatically publish the message to NATS
     } = options;
     
-    log_trace(correlationId, `Starting smartsend for subject: ${subject}`);
+    log_trace(correlation_id, `Starting smartsend for subject: ${subject}`);
     
     // Generate message metadata
-    const msgId = uuid4();
+    const msg_id = uuid4();
     
     // Process each payload in the list
     const payloads = [];
@@ -496,18 +464,18 @@ async function smartsend(subject, data, options = {}) {
         const payloadBytes = _serialize_data(payloadData, payloadType);
         const payloadSize = payloadBytes.byteLength;
         
-        log_trace(correlationId, `Serialized payload '${dataname}' (type: ${payloadType}) size: ${payloadSize} bytes`);
+        log_trace(correlation_id, `Serialized payload '${dataname}' (payload_type: ${payloadType}) size: ${payloadSize} bytes`);
         
         // Decision: Direct vs Link
-        if (payloadSize < sizeThreshold) {
+        if (payloadSize < size_threshold) {
             // Direct path - Base64 encode and send via NATS
-            const payloadB64 = arrayBufferToBase64(payloadBytes);
+            const payloadB64 = uint8ArrayToBase64(payloadBytes);
-            log_trace(correlationId, `Using direct transport for ${payloadSize} bytes`);
+            log_trace(correlation_id, `Using direct transport for ${payloadSize} bytes`);
             
             // Create MessagePayload for direct transport
             const payloadObj = new MessagePayload({
                 dataname: dataname,
-                type: payloadType,
+                payload_type: payloadType,
                 transport: "direct",
                 encoding: "base64",
                 size: payloadSize,
@@ -517,22 +485,22 @@ async function smartsend(subject, data, options = {}) {
             payloads.push(payloadObj);
         } else {
             // Link path - Upload to HTTP server, send URL via NATS
-            log_trace(correlationId, `Using link transport, uploading to fileserver`);
+            log_trace(correlation_id, `Using link transport, uploading to fileserver`);
             
-            // Upload to HTTP server
+            // Upload to HTTP server using plik_oneshot_upload handler
-            const response = await fileserverUploadHandler(fileserverUrl, dataname, payloadBytes, correlationId);
+            const response = await fileserver_upload_handler(fileserver_url, dataname, payloadBytes);
             
             if (response.status !== 200) {
                 throw new Error(`Failed to upload data to fileserver: ${response.status}`);
             }
             
             const url = response.url;
-            log_trace(correlationId, `Uploaded to URL: ${url}`);
+            log_trace(correlation_id, `Uploaded to URL: ${url}`);
             
             // Create MessagePayload for link transport
             const payloadObj = new MessagePayload({
                 dataname: dataname,
-                type: payloadType,
+                payload_type: payloadType,
                 transport: "link",
                 encoding: "none",
                 size: payloadSize,
@@ -545,16 +513,16 @@ async function smartsend(subject, data, options = {}) {
     
     // Create MessageEnvelope with all payloads
     const env = new MessageEnvelope({
-        correlationId: correlationId,
+        correlation_id: correlation_id,
-        msgId: msgId,
+        msg_id: msg_id,
-        sendTo: subject,
+        send_to: subject,
-        msgPurpose: msgPurpose,
+        msg_purpose: msg_purpose,
-        senderName: senderName,
+        sender_name: sender_name,
-        receiverName: receiverName,
+        receiver_name: receiver_name,
-        receiverId: receiverId,
+        receiver_id: receiver_id,
-        replyTo: replyTo,
+        reply_to: reply_to,
-        replyToMsgId: replyToMsgId,
+        reply_to_msg_id: reply_to_msg_id,
-        brokerURL: natsUrl,
+        broker_url: broker_url,
         payloads: payloads
     });
     
@@ -562,11 +530,11 @@ async function smartsend(subject, data, options = {}) {
     const env_json_str = env.toString();
     
     // Publish to NATS if isPublish is true
-    if (isPublish) {
+    if (is_publish) {
-        await publish_message(natsUrl, subject, env_json_str, correlationId);
+        await publish_message(broker_url, subject, env_json_str, correlation_id);
     }
     
-    // Return both envelope and JSON string (tuple-like structure)
+    // Return both envelope and JSON string (tuple-like structure, matching Julia API)
     return {
         env: env,
         env_json_str: env_json_str
@@ -574,11 +542,11 @@ async function smartsend(subject, data, options = {}) {
 }
 
 // Helper: Publish message to NATS
-async function publish_message(natsUrl, subject, message, correlation_id) {
+async function publish_message(broker_url, subject, message, correlation_id) {
     /**
      * Publish a message to a NATS subject with proper connection management
      * 
-     * @param {string} natsUrl - NATS server URL
+     * @param {string} broker_url - NATS server URL
      * @param {string} subject - NATS subject to publish to
      * @param {string} message - JSON message to publish
      * @param {string} correlation_id - Correlation ID for logging
@@ -591,7 +559,7 @@ async function publish_message(natsUrl, subject, message, correlation_id) {
     
     // Example with nats.js:
     // import { connect } from 'nats';
-    // const nc = await connect({ servers: [natsUrl] });
+    // const nc = await connect({ servers: [broker_url] });
     // await nc.publish(subject, message);
     // nc.close();
     
@@ -599,7 +567,7 @@ async function publish_message(natsUrl, subject, message, correlation_id) {
     console.log(`[NATS PUBLISH] Subject: ${subject}, Message: ${message.substring(0, 100)}...`);
 }
 
-// SmartReceive function
+// SmartReceive function - matches Julia smartreceive signature and behavior
 async function smartreceive(msg, options = {}) {
     /**
      * Receive and process messages from NATS
@@ -609,25 +577,25 @@ async function smartreceive(msg, options = {}) {
      * 
      * @param {Object} msg - NATS message object with payload property
      * @param {Object} options - Additional options
-     * @param {Function} options.fileserverDownloadHandler - Function to handle downloading data from file server URLs
+     * @param {Function} options.fileserver_download_handler - Function to handle downloading data from file server URLs
-     * @param {number} options.maxRetries - Maximum retry attempts for fetching URL (default: 5)
+     * @param {number} options.max_retries - Maximum retry attempts for fetching URL (default: 5)
-     * @param {number} options.baseDelay - Initial delay for exponential backoff in ms (default: 100)
+     * @param {number} options.base_delay - Initial delay for exponential backoff in ms (default: 100)
-     * @param {number} options.maxDelay - Maximum delay for exponential backoff in ms (default: 5000)
+     * @param {number} options.max_delay - Maximum delay for exponential backoff in ms (default: 5000)
      * 
-     * @returns {Promise<Object>} - Envelope dictionary with metadata and payloads field containing list of {dataname, data, type} objects
+     * @returns {Promise<Object>} - JSON object of envelope with payloads field containing list of {dataname, data, type} tuples
      */
     const {
-        fileserverDownloadHandler = _fetch_with_backoff,
+        fileserver_download_handler = _fetch_with_backoff,
-        maxRetries = 5,
+        max_retries = 5,
-        baseDelay = 100,
+        base_delay = 100,
-        maxDelay = 5000
+        max_delay = 5000
     } = options;
     
     // Parse the JSON envelope
     const jsonStr = typeof msg.payload === 'string' ? msg.payload : new TextDecoder().decode(msg.payload);
     const json_data = JSON.parse(jsonStr);
     
-    log_trace(json_data.correlationId, `Processing received message`);
+    log_trace(json_data.correlation_id, `Processing received message`);
     
     // Process all payloads in the envelope
     const payloads_list = [];
@@ -642,32 +610,32 @@ async function smartreceive(msg, options = {}) {
         
         if (transport === "direct") {
             // Direct transport - payload is in the message
-            log_trace(json_data.correlationId, `Direct transport - decoding payload '${dataname}'`);
+            log_trace(json_data.correlation_id, `Direct transport - decoding payload '${dataname}'`);
             
             // Extract base64 payload from the payload
             const payload_b64 = payload.data;
             
             // Decode Base64 payload
-            const payload_bytes = base64ToArrayBuffer(payload_b64);
+            const payload_bytes = base64ToUint8Array(payload_b64);
             
             // Deserialize based on type
-            const data_type = payload.type;
+            const data_type = payload.payload_type;
-            const data = _deserialize_data(payload_bytes, data_type, json_data.correlationId);
+            const data = _deserialize_data(payload_bytes, data_type, json_data.correlation_id);
             
             payloads_list.push({ dataname, data, type: data_type });
         } else if (transport === "link") {
             // Link transport - payload is at URL
             const url = payload.data;
-            log_trace(json_data.correlationId, `Link transport - fetching '${dataname}' from URL: ${url}`);
+            log_trace(json_data.correlation_id, `Link transport - fetching '${dataname}' from URL: ${url}`);
             
             // Fetch with exponential backoff using the download handler
-            const downloaded_data = await fileserverDownloadHandler(
+            const downloaded_data = await fileserver_download_handler(
-                url, maxRetries, baseDelay, maxDelay, json_data.correlationId
+                url, max_retries, base_delay, max_delay, json_data.correlation_id
             );
             
             // Deserialize based on type
-            const data_type = payload.type;
+            const data_type = payload.payload_type;
-            const data = _deserialize_data(downloaded_data, data_type, json_data.correlationId);
+            const data = _deserialize_data(downloaded_data, data_type, json_data.correlation_id);
             
             payloads_list.push({ dataname, data, type: data_type });
         } else {
@@ -676,11 +644,74 @@ async function smartreceive(msg, options = {}) {
     }
     
     // Replace payloads array with the processed list of {dataname, data, type} tuples
+    // This matches Julia's smartreceive return format
     json_data.payloads = payloads_list;
     
     return json_data;
 }
 
+// plik_oneshot_upload - matches Julia plik_oneshot_upload function
+// Upload handler signature: plik_oneshot_upload(fileserver_url, dataname, data)
+// Returns: { status, uploadid, fileid, url }
+async function plik_oneshot_upload(file_server_url, dataname, data) {
+    /**
+     * Upload a single file to a plik server using one-shot mode
+     * This function uploads raw byte array to a plik server in one-shot mode (no upload session).
+     * It first creates a one-shot upload session by sending a POST request with {"OneShot": true},
+     * retrieves an upload ID and token, then uploads the file data as multipart form data using the token.
+     *
+     * This is the default upload handler used by smartsend.
+     * Custom handlers can be passed via the fileserver_upload_handler option.
+     *
+     * @param {string} file_server_url - Base URL of the plik server (e.g., "http://localhost:8080")
+     * @param {string} dataname - Name of the file being uploaded
+     * @param {Uint8Array} data - Raw byte data of the file content
+     * @returns {Promise<Object>} - Dictionary with keys: status, uploadid, fileid, url
+     */
+    
+    // Step 1: Get upload ID and token
+    const url_getUploadID = `${file_server_url}/upload`;
+    const headers = { "Content-Type": "application/json" };
+    const body = JSON.stringify({ OneShot: true });
+    
+    let http_response = await fetch(url_getUploadID, {
+        method: "POST",
+        headers: headers,
+        body: body
+    });
+    
+    const response_json = await http_response.json();
+    const uploadid = response_json.id;
+    const uploadtoken = response_json.uploadToken;
+    
+    // Step 2: Upload file data
+    const url_upload = `${file_server_url}/file/${uploadid}`;
+    
+    // Create multipart form data
+    const formData = new FormData();
+    const blob = new Blob([data], { type: "application/octet-stream" });
+    formData.append("file", blob, dataname);
+    
+    http_response = await fetch(url_upload, {
+        method: "POST",
+        headers: { "X-UploadToken": uploadtoken },
+        body: formData
+    });
+    
+    const fileResponseJson = await http_response.json();
+    const fileid = fileResponseJson.id;
+    
+    // URL of the uploaded data e.g. "http://192.168.1.20:8080/file/3F62E/4AgGT/test.zip"
+    const url = `${file_server_url}/file/${uploadid}/${fileid}/${encodeURIComponent(dataname)}`;
+    
+    return {
+        status: http_response.status,
+        uploadid: uploadid,
+        fileid: fileid,
+        url: url
+    };
+}
+
 // Export for Node.js
 if (typeof module !== 'undefined' && module.exports) {
     module.exports = {
@@ -692,6 +723,7 @@ if (typeof module !== 'undefined' && module.exports) {
         _deserialize_data,
         _fetch_with_backoff,
         _upload_to_fileserver,
+        plik_oneshot_upload,
         DEFAULT_SIZE_THRESHOLD,
         DEFAULT_NATS_URL,
         DEFAULT_FILESERVER_URL,
@@ -711,6 +743,7 @@ if (typeof window !== 'undefined') {
         _deserialize_data,
         _fetch_with_backoff,
         _upload_to_fileserver,
+        plik_oneshot_upload,
         DEFAULT_SIZE_THRESHOLD,
         DEFAULT_NATS_URL,
         DEFAULT_FILESERVER_URL,

src/nats_bridge.py

@@ -1,45 +1,76 @@
 """
-Micropython NATS Bridge - Bi-Directional Data Bridge for Micropython
+Python NATS Bridge - Bi-Directional Data Bridge
 
 This module provides functionality for sending and receiving data over NATS
 using the Claim-Check pattern for large payloads.
 
 Supported types: "text", "dictionary", "table", "image", "audio", "video", "binary"
+
+Multi-Payload Support (Standard API):
+The system uses a standardized list-of-tuples format for all payload operations.
+Even when sending a single payload, the user must wrap it in a list.
+
+API Standard:
+    # Input format for smartsend (always a list of tuples with type info)
+    [(dataname1, data1, type1), (dataname2, data2, type2), ...]
+    
+    # Output format for smartreceive (returns a dictionary with payloads field containing list of tuples)
+    # Returns: Dict with envelope metadata and payloads field containing list of tuples
+    # {
+    #   "correlation_id": "...",
+    #   "msg_id": "...",
+    #   "timestamp": "...",
+    #   "send_to": "...",
+    #   "msg_purpose": "...",
+    #   "sender_name": "...",
+    #   "sender_id": "...",
+    #   "receiver_name": "...",
+    #   "receiver_id": "...",
+    #   "reply_to": "...",
+    #   "reply_to_msg_id": "...",
+    #   "broker_url": "...",
+    #   "metadata": {...},
+    #   "payloads": [(dataname1, data1, type1), (dataname2, data2, type2), ...]
+    # }
 """
 
 import json
-import random
 import time
-import usocket
-import uselect
-import ustruct
 import uuid
 
-try:
-    import ussl
-    HAS_SSL = True
-except ImportError:
-    HAS_SSL = False
-
 # Constants
 DEFAULT_SIZE_THRESHOLD = 1000000  # 1MB - threshold for switching from direct to link transport
-DEFAULT_NATS_URL = "nats://localhost:4222"
+DEFAULT_BROKER_URL = "nats://localhost:4222"
 DEFAULT_FILESERVER_URL = "http://localhost:8080"
 
 # ============================================= 100 ============================================== #
 
 
 class MessagePayload:
-    """Internal message payload structure representing a single payload within a NATS message envelope."""
+    """Internal message payload structure representing a single payload within a NATS message envelope.
     
-    def __init__(self, data, msg_type, id="", dataname="", transport="direct", 
+    This structure represents a single payload within a NATS message envelope.
+    It supports both direct transport (base64-encoded data) and link transport (URL-based).
+    
+    Attributes:
+        id: Unique identifier for this payload (e.g., "uuid4")
+        dataname: Name of the payload (e.g., "login_image")
+        payload_type: Payload type ("text", "dictionary", "table", "image", "audio", "video", "binary")
+        transport: Transport method ("direct" or "link")
+        encoding: Encoding method ("none", "json", "base64", "arrow-ipc")
+        size: Size of the payload in bytes
+        data: Payload data (bytes for direct, URL for link)
+        metadata: Optional metadata dictionary
+    """
+    
+    def __init__(self, data, payload_type, id="", dataname="", transport="direct", 
                  encoding="none", size=0, metadata=None):
         """
         Initialize a MessagePayload.
         
         Args:
-            data: Payload data (bytes for direct, URL string for link)
+            data: Payload data (base64 string for direct, URL string for link)
-            msg_type: Payload type ("text", "dictionary", "table", "image", "audio", "video", "binary")
+            payload_type: Payload type ("text", "dictionary", "table", "image", "audio", "video", "binary")
             id: Unique identifier for this payload (auto-generated if empty)
             dataname: Name of the payload (auto-generated UUID if empty)
             transport: Transport method ("direct" or "link")
@@ -49,7 +80,7 @@ class MessagePayload:
         """
         self.id = id if id else self._generate_uuid()
         self.dataname = dataname if dataname else self._generate_uuid()
-        self.type = msg_type
+        self.payload_type = payload_type
         self.transport = transport
         self.encoding = encoding
         self.size = size
@@ -65,7 +96,7 @@ class MessagePayload:
         payload_dict = {
             "id": self.id,
             "dataname": self.dataname,
-            "type": self.type,
+            "payload_type": self.payload_type,
             "transport": self.transport,
             "encoding": self.encoding,
             "size": self.size,
@@ -106,7 +137,7 @@ class MessageEnvelope:
     
     def __init__(self, send_to, payloads, correlation_id="", msg_id="", timestamp="",
                  msg_purpose="", sender_name="", sender_id="", receiver_name="",
-                 receiver_id="", reply_to="", reply_to_msg_id="", broker_url=DEFAULT_NATS_URL,
+                 receiver_id="", reply_to="", reply_to_msg_id="", broker_url=DEFAULT_BROKER_URL,
                  metadata=None):
         """
         Initialize a MessageEnvelope.
@@ -152,20 +183,24 @@ class MessageEnvelope:
         return "2026-02-21T" + time.strftime("%H:%M:%S", time.localtime())
     
     def to_json(self):
-        """Convert envelope to JSON string."""
+        """Convert envelope to JSON string.
+        
+        Returns:
+            str: JSON string representation of the envelope using snake_case field names
+        """
         obj = {
-            "correlationId": self.correlation_id,
+            "correlation_id": self.correlation_id,
-            "msgId": self.msg_id,
+            "msg_id": self.msg_id,
             "timestamp": self.timestamp,
-            "sendTo": self.send_to,
+            "send_to": self.send_to,
-            "msgPurpose": self.msg_purpose,
+            "msg_purpose": self.msg_purpose,
-            "senderName": self.sender_name,
+            "sender_name": self.sender_name,
-            "senderId": self.sender_id,
+            "sender_id": self.sender_id,
-            "receiverName": self.receiver_name,
+            "receiver_name": self.receiver_name,
-            "receiverId": self.receiver_id,
+            "receiver_id": self.receiver_id,
-            "replyTo": self.reply_to,
+            "reply_to": self.reply_to,
-            "replyToMsgId": self.reply_to_msg_id,
+            "reply_to_msg_id": self.reply_to_msg_id,
-            "brokerURL": self.broker_url
+            "broker_url": self.broker_url
         }
         
         # Include metadata if not empty
@@ -188,68 +223,126 @@ def log_trace(correlation_id, message):
     print("[{}] [Correlation: {}] {}".format(timestamp, correlation_id, message))
 
 
-def _serialize_data(data, msg_type):
+def _serialize_data(data, payload_type):
     """Serialize data according to specified format.
     
+    This function serializes arbitrary data into a binary representation based on the specified type.
+    It supports multiple serialization formats for different data types.
+    
     Args:
         data: Data to serialize
-        msg_type: Target format ("text", "dictionary", "table", "image", "audio", "video", "binary")
+            - "text": String
+            - "dictionary": JSON-serializable dict
+            - "table": Tabular data (pandas DataFrame or list of dicts)
+            - "image", "audio", "video", "binary": bytes
+        payload_type: Target format ("text", "dictionary", "table", "image", "audio", "video", "binary")
     
     Returns:
         bytes: Binary representation of the serialized data
+    
+    Example:
+        >>> text_bytes = _serialize_data("Hello World", "text")
+        >>> json_bytes = _serialize_data({"key": "value"}, "dictionary")
+        >>> table_bytes = _serialize_data([{"id": 1, "name": "Alice"}], "table")
     """
-    if msg_type == "text":
+    if payload_type == "text":
         if isinstance(data, str):
             return data.encode('utf-8')
         else:
             raise ValueError("Text data must be a string")
     
-    elif msg_type == "dictionary":
+    elif payload_type == "dictionary":
         if isinstance(data, dict):
             json_str = json.dumps(data)
             return json_str.encode('utf-8')
         else:
             raise ValueError("Dictionary data must be a dict")
     
-    elif msg_type in ("image", "audio", "video", "binary"):
+    elif payload_type == "table":
+        # Support pandas DataFrame or list of dicts
+        try:
+            import pandas as pd
+            if isinstance(data, pd.DataFrame):
+                # Convert DataFrame to JSON and then to bytes
+                json_str = data.to_json(orient='records', force_ascii=False)
+                return json_str.encode('utf-8')
+            elif isinstance(data, list) and len(data) > 0 and isinstance(data[0], dict):
+                # List of dicts
+                json_str = json.dumps(data)
+                return json_str.encode('utf-8')
+            else:
+                raise ValueError("Table data must be a pandas DataFrame or list of dicts")
+        except ImportError:
+            # Fallback: if pandas not available, treat as list of dicts
+            if isinstance(data, list):
+                json_str = json.dumps(data)
+                return json_str.encode('utf-8')
+            else:
+                raise ValueError("Table data requires pandas DataFrame or list of dicts (pandas not available)")
+    
+    elif payload_type in ("image", "audio", "video", "binary"):
         if isinstance(data, bytes):
             return data
         else:
-            raise ValueError("{} data must be bytes".format(msg_type.capitalize()))
+            raise ValueError("{} data must be bytes".format(payload_type.capitalize()))
     
     else:
-        raise ValueError("Unknown type: {}".format(msg_type))
+        raise ValueError("Unknown payload_type: {}".format(payload_type))
 
 
-def _deserialize_data(data_bytes, msg_type, correlation_id):
+def _deserialize_data(data_bytes, payload_type, correlation_id):
     """Deserialize bytes to data based on type.
     
+    This function converts serialized bytes back to Python data based on type.
+    It handles "text" (string), "dictionary" (JSON deserialization), "table" (JSON deserialization),
+    "image" (binary data), "audio" (binary data), "video" (binary data), and "binary" (binary data).
+    
     Args:
         data_bytes: Serialized data as bytes
-        msg_type: Data type ("text", "dictionary", "table", "image", "audio", "video", "binary")
+        payload_type: Data type ("text", "dictionary", "table", "image", "audio", "video", "binary")
         correlation_id: Correlation ID for logging
     
     Returns:
-        Deserialized data
+        Deserialized data:
+            - "text": str
+            - "dictionary": dict
+            - "table": list of dicts (or pandas DataFrame if available)
+            - "image", "audio", "video", "binary": bytes
+    
+    Example:
+        >>> text_data = _deserialize_data(b"Hello", "text", "corr_id")
+        >>> json_data = _deserialize_data(b'{"key": "value"}', "dictionary", "corr_id")
+        >>> table_data = _deserialize_data(b'[{"id": 1}]', "table", "corr_id")
     """
-    if msg_type == "text":
+    if payload_type == "text":
         return data_bytes.decode('utf-8')
     
-    elif msg_type == "dictionary":
+    elif payload_type == "dictionary":
         json_str = data_bytes.decode('utf-8')
         return json.loads(json_str)
     
-    elif msg_type in ("image", "audio", "video", "binary"):
+    elif payload_type == "table":
+        # Deserialize table data (JSON format)
+        json_str = data_bytes.decode('utf-8')
+        table_data = json.loads(json_str)
+        # If pandas is available, try to convert to DataFrame
+        try:
+            import pandas as pd
+            return pd.DataFrame(table_data)
+        except ImportError:
+            return table_data
+    
+    elif payload_type in ("image", "audio", "video", "binary"):
         return data_bytes
     
     else:
-        raise ValueError("Unknown type: {}".format(msg_type))
+        raise ValueError("Unknown payload_type: {}".format(payload_type))
 
 
 class NATSConnection:
-    """Simple NATS connection for Micropython."""
+    """Simple NATS connection for Python and Micropython."""
     
-    def __init__(self, url=DEFAULT_NATS_URL):
+    def __init__(self, url=DEFAULT_BROKER_URL):
         """Initialize NATS connection.
         
         Args:
@@ -276,9 +369,19 @@ class NATSConnection:
     
     def connect(self):
         """Connect to NATS server."""
+        # Use socket for both Python and Micropython
+        try:
+            import socket
+            addr = socket.getaddrinfo(self.host, self.port)[0][-1]
+            self.conn = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+            self.conn.connect(addr)
+        except NameError:
+            # Micropython fallback
+            import usocket
             addr = usocket.getaddrinfo(self.host, self.port)[0][-1]
             self.conn = usocket.socket()
             self.conn.connect(addr)
+        
         log_trace("", "Connected to NATS server at {}:{}".format(self.host, self.port))
     
     def publish(self, subject, message):
@@ -294,7 +397,15 @@ class NATSConnection:
         # Simple NATS protocol implementation
         msg = "PUB {} {}\r\n".format(subject, len(message))
         msg = msg.encode('utf-8') + message + b"\r\n"
+        
+        try:
+            import socket
             self.conn.send(msg)
+        except NameError:
+            # Micropython fallback
+            import usocket
+            self.conn.send(msg)
+        
         log_trace("", "Message published to {}".format(subject))
     
     def subscribe(self, subject, callback):
@@ -335,11 +446,14 @@ class NATSConnection:
 def _fetch_with_backoff(url, max_retries=5, base_delay=100, max_delay=5000, correlation_id=""):
     """Fetch data from URL with exponential backoff.
     
+    This function retrieves data from a URL with retry logic using
+    exponential backoff to handle transient failures.
+    
     Args:
         url: URL to fetch from
-        max_retries: Maximum number of retry attempts
+        max_retries: Maximum number of retry attempts (default: 5)
-        base_delay: Initial delay in milliseconds
+        base_delay: Initial delay in milliseconds (default: 100)
-        max_delay: Maximum delay in milliseconds
+        max_delay: Maximum delay in milliseconds (default: 5000)
         correlation_id: Correlation ID for logging
     
     Returns:
@@ -347,33 +461,54 @@ def _fetch_with_backoff(url, max_retries=5, base_delay=100, max_delay=5000, corr
     
     Raises:
         Exception: If all retry attempts fail
+    
+    Example:
+        >>> data = _fetch_with_backoff("http://example.com/file.zip", 5, 100, 5000, "corr_id")
     """
     delay = base_delay
     for attempt in range(1, max_retries + 1):
         try:
             # Simple HTTP GET request
-            # This is a simplified implementation
+            # Try urequests for Micropython first, then requests for Python
-            # For production, you'd want a proper HTTP client
+            try:
                 import urequests
                 response = urequests.get(url)
-            if response.status_code == 200:
+                status_code = response.status_code
+                content = response.content
+            except ImportError:
+                try:
+                    import requests
+                    response = requests.get(url)
+                    response.raise_for_status()
+                    status_code = response.status_code
+                    content = response.content
+                except ImportError:
+                    raise Exception("No HTTP library available (urequests or requests)")
+            
+            if status_code == 200:
                 log_trace(correlation_id, "Successfully fetched data from {} on attempt {}".format(url, attempt))
-                return response.content
+                return content
             else:
-                raise Exception("Failed to fetch: {}".format(response.status_code))
+                raise Exception("Failed to fetch: {}".format(status_code))
         except Exception as e:
             log_trace(correlation_id, "Attempt {} failed: {}".format(attempt, str(e)))
             if attempt < max_retries:
                 time.sleep(delay / 1000.0)
                 delay = min(delay * 2, max_delay)
     
+    raise Exception("Failed to fetch data after {} attempts".format(max_retries))
 
-def plik_oneshot_upload(file_server_url, filename, data):
+
+def plik_oneshot_upload(fileserver_url, dataname, data):
     """Upload a single file to a plik server using one-shot mode.
     
+    This function uploads raw byte data to a plik server in one-shot mode (no upload session).
+    It first creates a one-shot upload session by sending a POST request with {"OneShot": true},
+    retrieves an upload ID and token, then uploads the file data as multipart form data using the token.
+    
     Args:
-        file_server_url: Base URL of the plik server
+        fileserver_url: Base URL of the plik server (e.g., "http://localhost:8080")
-        filename: Name of the file being uploaded
+        dataname: Name of the file being uploaded
         data: Raw byte data of the file content
     
     Returns:
@@ -382,23 +517,31 @@ def plik_oneshot_upload(file_server_url, filename, data):
             - "uploadid": ID of the one-shot upload session
             - "fileid": ID of the uploaded file within the session
             - "url": Full URL to download the uploaded file
+    
+    Example:
+        >>> result = plik_oneshot_upload("http://localhost:8080", "test.txt", b"hello world")
+        >>> result["status"], result["uploadid"], result["fileid"], result["url"]
     """
-    import urequests
     import json
     
+    try:
+        import urequests
+    except ImportError:
+        import requests as urequests
+    
     # Get upload ID
-    url_get_upload_id = "{}/upload".format(file_server_url)
+    url_get_upload_id = "{}/upload".format(fileserver_url)
     headers = {"Content-Type": "application/json"}
     body = json.dumps({"OneShot": True})
     
     response = urequests.post(url_get_upload_id, headers=headers, data=body)
-    response_json = json.loads(response.content)
+    response_json = json.loads(response.text if hasattr(response, 'text') else response.content)
     
     uploadid = response_json.get("id")
     uploadtoken = response_json.get("uploadToken")
     
     # Upload file
-    url_upload = "{}/file/{}".format(file_server_url, uploadid)
+    url_upload = "{}/file/{}".format(fileserver_url, uploadid)
     headers = {"X-UploadToken": uploadtoken}
     
     # For Micropython, we need to construct the multipart form data manually
@@ -407,7 +550,7 @@ def plik_oneshot_upload(file_server_url, filename, data):
     
     # Create multipart body
     part1 = "--{}\r\n".format(boundary)
-    part1 += "Content-Disposition: form-data; name=\"file\"; filename=\"{}\"\r\n".format(filename)
+    part1 += "Content-Disposition: form-data; name=\"file\"; filename=\"{}\"\r\n".format(dataname)
     part1 += "Content-Type: application/octet-stream\r\n\r\n"
     part1_bytes = part1.encode('utf-8')
     
@@ -421,10 +564,10 @@ def plik_oneshot_upload(file_server_url, filename, data):
     content_type = "multipart/form-data; boundary={}".format(boundary)
     
     response = urequests.post(url_upload, headers={"Content-Type": content_type}, data=full_body)
-    response_json = json.loads(response.content)
+    response_json = json.loads(response.text if hasattr(response, 'text') else response.content)
     
     fileid = response_json.get("id")
-    url = "{}/file/{}/{}".format(file_server_url, uploadid, filename)
+    url = "{}/file/{}/{}".format(fileserver_url, uploadid, dataname)
     
     return {
         "status": response.status_code,
@@ -434,7 +577,7 @@ def plik_oneshot_upload(file_server_url, filename, data):
     }
 
 
-def smartsend(subject, data, nats_url=DEFAULT_NATS_URL, fileserver_url=DEFAULT_FILESERVER_URL,
+def smartsend(subject, data, broker_url=DEFAULT_BROKER_URL, fileserver_url=DEFAULT_FILESERVER_URL,
               fileserver_upload_handler=plik_oneshot_upload, size_threshold=DEFAULT_SIZE_THRESHOLD,
               correlation_id=None, msg_purpose="chat", sender_name="NATSBridge",
               receiver_name="", receiver_id="", reply_to="", reply_to_msg_id="", is_publish=True):
@@ -445,29 +588,46 @@ def smartsend(subject, data, nats_url=DEFAULT_NATS_URL, fileserver_url=DEFAULT_F
     publishes directly over NATS. Otherwise, it uploads the data to a fileserver and publishes 
     only the download URL over NATS.
     
+    API Standard:
+        - Input format: List of (dataname, data, payload_type) tuples
+        - Even single payloads must be wrapped in a list
+        - Each payload can have a different type, enabling mixed-content messages
+    
     Args:
         subject: NATS subject to publish the message to
-        data: List of (dataname, data, type) tuples to send
+        data: List of (dataname, data, payload_type) tuples to send
-        nats_url: URL of the NATS server
+            - dataname: Name of the payload
+            - data: The actual data to send
+            - payload_type: Payload type ("text", "dictionary", "table", "image", "audio", "video", "binary")
+            - Example: [("message", "Hello World!", "text"), ("config", {"key": "value"}, "dictionary")]
+        broker_url: URL of the NATS server
         fileserver_url: URL of the HTTP file server
-        fileserver_upload_handler: Function to handle fileserver uploads
+        fileserver_upload_handler: Function to handle fileserver uploads (must return dict with "status", "uploadid", "fileid", "url" keys)
-        size_threshold: Threshold in bytes separating direct vs link transport
+        size_threshold: Threshold in bytes separating direct vs link transport (default: 1MB)
-        correlation_id: Optional correlation ID for tracing
+        correlation_id: Optional correlation ID for tracing; if None, a UUID is generated
-        msg_purpose: Purpose of the message
+        msg_purpose: Purpose of the message ("ACK", "NACK", "updateStatus", "shutdown", "chat", etc.)
         sender_name: Name of the sender
-        receiver_name: Name of the receiver
+        receiver_name: Name of the receiver (empty string means broadcast)
-        receiver_id: UUID of the receiver
+        receiver_id: UUID of the receiver (empty string means broadcast)
-        reply_to: Topic to reply to
+        reply_to: Topic to reply to (empty string if no reply expected)
         reply_to_msg_id: Message ID this message is replying to
         is_publish: Whether to automatically publish the message to NATS (default: True)
+            - When True: message is published to NATS
+            - When False: returns envelope and JSON string without publishing
     
     Returns:
         tuple: (env, env_json_str) where:
             - env: MessageEnvelope object with all metadata and payloads
             - env_json_str: JSON string representation of the envelope for publishing
+    
+    Example:
+        >>> data = [("message", "Hello World!", "text")]
+        >>> env, env_json_str = smartsend("/test", data)
+        >>> # env: MessageEnvelope with all metadata and payloads
+        >>> # env_json_str: JSON string for publishing
     """
     # Generate correlation ID if not provided
-    cid = correlation_id if correlation_id else str(uuid.uuid4())
+    cid = correlation_id if correlation_id is not None else str(uuid.uuid4())
     
     log_trace(cid, "Starting smartsend for subject: {}".format(subject))
     
@@ -482,16 +642,19 @@ def smartsend(subject, data, nats_url=DEFAULT_NATS_URL, fileserver_url=DEFAULT_F
         payload_bytes = _serialize_data(payload_data, payload_type)
         
         payload_size = len(payload_bytes)
-        log_trace(cid, "Serialized payload '{}' (type: {}) size: {} bytes".format(
+        log_trace(cid, "Serialized payload '{}' (payload_type: {}) size: {} bytes".format(
             dataname, payload_type, payload_size))
         
         # Decision: Direct vs Link
         if payload_size < size_threshold:
             # Direct path - Base64 encode and send via NATS
-            payload_b64 = _serialize_data(payload_bytes, "binary")  # Already bytes
             # Convert to base64 string for JSON
+            try:
                 import ubinascii
                 payload_b64_str = ubinascii.b2a_base64(payload_bytes).decode('utf-8').strip()
+            except ImportError:
+                import base64
+                payload_b64_str = base64.b64encode(payload_bytes).decode('utf-8')
             
             log_trace(cid, "Using direct transport for {} bytes".format(payload_size))
             
@@ -514,10 +677,10 @@ def smartsend(subject, data, nats_url=DEFAULT_NATS_URL, fileserver_url=DEFAULT_F
             # Upload to HTTP server
             response = fileserver_upload_handler(fileserver_url, dataname, payload_bytes)
             
-            if response["status"] != 200:
+            if response.get("status") != 200:
-                raise Exception("Failed to upload data to fileserver: {}".format(response["status"]))
+                raise Exception("Failed to upload data to fileserver: {}".format(response.get("status")))
             
-            url = response["url"]
+            url = response.get("url")
             log_trace(cid, "Uploaded to URL: {}".format(url))
             
             # Create MessagePayload for link transport
@@ -546,7 +709,7 @@ def smartsend(subject, data, nats_url=DEFAULT_NATS_URL, fileserver_url=DEFAULT_F
         receiver_id=receiver_id,
         reply_to=reply_to,
         reply_to_msg_id=reply_to_msg_id,
-        broker_url=nats_url,
+        broker_url=broker_url,
         metadata={}
     )
     
@@ -554,7 +717,7 @@ def smartsend(subject, data, nats_url=DEFAULT_NATS_URL, fileserver_url=DEFAULT_F
     
     # Publish to NATS if is_publish is True
     if is_publish:
-        nats_conn = NATSConnection(nats_url)
+        nats_conn = NATSConnection(broker_url)
         nats_conn.connect()
         nats_conn.publish(subject, msg_json)
         nats_conn.close()
@@ -570,19 +733,39 @@ def smartreceive(msg, fileserver_download_handler=_fetch_with_backoff, max_retri
     This function processes incoming NATS messages, handling both direct transport
     (base64 decoded payloads) and link transport (URL-based payloads).
     
+    API Standard:
+        - Returns a dictionary with envelope metadata and 'payloads' field
+        - payloads field contains list of (dataname, data, payload_type) tuples
+        - Supports mixed-content messages with different payload types
+    
     Args:
-        msg: NATS message to process (dict with payload data)
+        msg: NATS message to process (dict or JSON string with envelope data)
         fileserver_download_handler: Function to handle downloading data from file server URLs
-        max_retries: Maximum retry attempts for fetching URL
+            Receives: (url, max_retries, base_delay, max_delay, correlation_id)
-        base_delay: Initial delay for exponential backoff in ms
+            Returns: bytes (the downloaded data)
-        max_delay: Maximum delay for exponential backoff in ms
+        max_retries: Maximum retry attempts for fetching URL (default: 5)
+        base_delay: Initial delay for exponential backoff in ms (default: 100)
+        max_delay: Maximum delay for exponential backoff in ms (default: 5000)
     
     Returns:
-        dict: Envelope dictionary with metadata and 'payloads' field containing list of (dataname, data, type) tuples
+        dict: Envelope dictionary with metadata and 'payloads' field containing list of 
+              (dataname, data, payload_type) tuples
+        - Envelope fields: correlation_id, msg_id, timestamp, send_to, msg_purpose,
+          sender_name, sender_id, receiver_name, receiver_id, reply_to, reply_to_msg_id,
+          broker_url, metadata
+        - payloads: List of (dataname, data, payload_type) tuples
+    
+    Example:
+        >>> env = smartreceive(msg)
+        >>> # env contains envelope metadata and payloads field
+        >>> # env["payloads"] = [(dataname1, data1, payload_type1), ...]
+        >>> for dataname, data, payload_type in env["payloads"]:
+        ...     print("Received {} of type {}: {}".format(dataname, payload_type, data))
     """
     # Parse the JSON envelope
     json_data = msg if isinstance(msg, dict) else json.loads(msg)
-    log_trace(json_data.get("correlationId", ""), "Processing received message")
+    correlation_id = json_data.get("correlation_id", "")
+    log_trace(correlation_id, "Processing received message")
     
     # Process all payloads in the envelope
     payloads_list = []
@@ -596,43 +779,47 @@ def smartreceive(msg, fileserver_download_handler=_fetch_with_backoff, max_retri
         dataname = payload.get("dataname", "")
         
         if transport == "direct":
-            log_trace(json_data.get("correlationId", ""), 
+            log_trace(correlation_id, 
                      "Direct transport - decoding payload '{}'".format(dataname))
             
             # Extract base64 payload from the payload
             payload_b64 = payload.get("data", "")
             
             # Decode Base64 payload
+            try:
                 import ubinascii
                 payload_bytes = ubinascii.a2b_base64(payload_b64.encode('utf-8'))
+            except ImportError:
+                import base64
+                payload_bytes = base64.b64decode(payload_b64)
             
             # Deserialize based on type
-            data_type = payload.get("type", "")
+            payload_type = payload.get("payload_type", "")
-            data = _deserialize_data(payload_bytes, data_type, json_data.get("correlationId", ""))
+            data = _deserialize_data(payload_bytes, payload_type, correlation_id)
             
-            payloads_list.append((dataname, data, data_type))
+            payloads_list.append((dataname, data, payload_type))
             
         elif transport == "link":
             # Extract download URL from the payload
             url = payload.get("data", "")
-            log_trace(json_data.get("correlationId", ""),
+            log_trace(correlation_id,
                       "Link transport - fetching '{}' from URL: {}".format(dataname, url))
             
             # Fetch with exponential backoff
             downloaded_data = fileserver_download_handler(
-                url, max_retries, base_delay, max_delay, json_data.get("correlationId", "")
+                url, max_retries, base_delay, max_delay, correlation_id
             )
             
             # Deserialize based on type
-            data_type = payload.get("type", "")
+            payload_type = payload.get("payload_type", "")
-            data = _deserialize_data(downloaded_data, data_type, json_data.get("correlationId", ""))
+            data = _deserialize_data(downloaded_data, payload_type, correlation_id)
             
-            payloads_list.append((dataname, data, data_type))
+            payloads_list.append((dataname, data, payload_type))
             
         else:
             raise ValueError("Unknown transport type for payload '{}': {}".format(dataname, transport))
     
-    # Replace payloads field with the processed list of (dataname, data, type) tuples
+    # Replace payloads field with the processed list of (dataname, data, payload_type) tuples
     json_data["payloads"] = payloads_list
     
     return json_data
@@ -651,11 +838,11 @@ def get_timestamp():
 
 # Example usage
 if __name__ == "__main__":
-    print("NATSBridge for Micropython")
+    print("NATSBridge - Bi-Directional Data Bridge")
-    print("=========================")
+    print("=======================================")
     print("This module provides:")
-    print("  - MessageEnvelope: Message envelope structure")
+    print("  - MessageEnvelope: Message envelope structure with snake_case fields")
-    print("  - MessagePayload: Payload structure")
+    print("  - MessagePayload: Payload structure with payload_type field")
     print("  - smartsend: Send data via NATS with automatic transport selection")
     print("  - smartreceive: Receive and process messages from NATS")
     print("  - plik_oneshot_upload: Upload files to HTTP file server")
@@ -663,10 +850,22 @@ if __name__ == "__main__":
     print()
     print("Usage:")
     print("  from nats_bridge import smartsend, smartreceive")
-    print("  data = [(\"message\", \"Hello World\", \"text\")]")
+    print()
-    print("  env = smartsend(\"my.subject\", data)")
+    print("  # Send data (list of (dataname, data, payload_type) tuples)")
+    print("  # Even single payloads must be wrapped in a list")
+    print("  data = [(\"message\", \"Hello World!\", \"text\")]")
+    print("  env, env_json_str = smartsend(\"my.subject\", data)")
     print()
     print("  # On receiver:")
-    print("  payloads = smartreceive(msg)")
+    print("  env = smartreceive(msg)")
-    print("  for dataname, data, type in payloads:")
+    print("  # env contains envelope metadata and payloads field")
-    print("      print(f\"Received {dataname} of type {type}: {data}\")")
+    print("  for dataname, data, payload_type in env[\"payloads\"]:")
+    print("      print(\"Received {} of type {}: {}\".format(dataname, payload_type, data))")
+    print()
+    print("  # Mixed-content message example:")
+    print("  mixed_data = [")
+    print("      (\"text\", \"Hello!\", \"text\"),")
+    print("      (\"config\", {\"key\": \"value\"}, \"dictionary\"),")
+    print("      (\"table\", [{\"id\": 1}], \"table\")")
+    print("  ]")
+    print("  smartsend(\"/chat\", mixed_data)")