1061 lines
31 KiB
Markdown
1061 lines
31 KiB
Markdown
# Specification: NATSBridge
|
|
|
|
**Version**: 1.0.0
|
|
**Date**: 2026-03-13
|
|
**Status**: Active
|
|
**Ground Truth**: [`src/NATSBridge.jl`](../src/NATSBridge.jl)
|
|
**Specification Format**: JSON Schema + AsyncAPI
|
|
|
|
---
|
|
|
|
## Executive Summary
|
|
|
|
This document defines the **technical contract** for NATSBridge - the cross-platform bi-directional data bridge that enables seamless communication between **Julia**, **JavaScript**, **Python**, and **MicroPython** applications using NATS as the message bus.
|
|
|
|
This specification serves as the single source of truth for:
|
|
- **Inputs**: What data structures are accepted by `smartsend()`
|
|
- **Outputs**: What data structures are returned by `smartreceive()`
|
|
- **Data Shapes**: Exact field names, types, and constraints
|
|
- **Error Codes**: Standardized error responses for failure scenarios
|
|
|
|
---
|
|
|
|
## Specification Versioning
|
|
|
|
| Component | Version | Notes |
|
|
|-----------|---------|-------|
|
|
| Specification | 1.0.0 | Initial release |
|
|
| Protocol | v1 | Message envelope protocol version |
|
|
|
|
---
|
|
|
|
## Message Envelope Schema
|
|
|
|
### Envelope Structure (JSON)
|
|
|
|
```json
|
|
{
|
|
"correlation_id": "string (UUID)",
|
|
"msg_id": "string (UUID)",
|
|
"timestamp": "string (ISO 8601 UTC)",
|
|
"send_to": "string",
|
|
"msg_purpose": "string",
|
|
"sender_name": "string",
|
|
"sender_id": "string (UUID)",
|
|
"receiver_name": "string",
|
|
"receiver_id": "string (UUID)",
|
|
"reply_to": "string",
|
|
"reply_to_msg_id": "string",
|
|
"broker_url": "string",
|
|
"metadata": "object",
|
|
"payloads": [
|
|
{
|
|
"id": "string (UUID)",
|
|
"dataname": "string",
|
|
"payload_type": "string",
|
|
"transport": "string",
|
|
"encoding": "string",
|
|
"size": "integer",
|
|
"data": "string or URL",
|
|
"metadata": "object"
|
|
}
|
|
]
|
|
}
|
|
```
|
|
|
|
### Field Definitions
|
|
|
|
| Field | Type | Required | Validation | Description |
|
|
|-------|------|----------|------------|-------------|
|
|
| `correlation_id` | `string` | Yes | UUID v4 format | Track message flow across distributed systems |
|
|
| `msg_id` | `string` | Yes | UUID v4 format | Unique identifier for this specific message |
|
|
| `timestamp` | `string` | Yes | ISO 8601 UTC | Message publication timestamp (e.g., `2026-03-13T07:02:50.443Z`) |
|
|
| `send_to` | `string` | Yes | Non-empty string | NATS subject/topic to publish the message to |
|
|
| `msg_purpose` | `string` | Yes | Enum | Purpose of the message (see `msg_purpose` enum) |
|
|
| `sender_name` | `string` | Yes | Non-empty string | Name of the sender application |
|
|
| `sender_id` | `string` | Yes | UUID v4 format | Unique identifier for the sender |
|
|
| `receiver_name` | `string` | Yes | Any string | Name of the receiver (empty = broadcast) |
|
|
| `receiver_id` | `string` | Yes | Any string | UUID of the receiver (empty = broadcast) |
|
|
| `reply_to` | `string` | Yes | Any string | Topic where receiver should reply (empty = no reply expected) |
|
|
| `reply_to_msg_id` | `string` | Yes | Any string | Message ID this message is replying to |
|
|
| `broker_url` | `string` | Yes | Valid URL | NATS broker URL |
|
|
| `metadata` | `object` | No | Any JSON object | Message-level metadata |
|
|
| `payloads` | `array` | Yes | Non-empty array | List of payload objects |
|
|
|
|
---
|
|
|
|
## Payload Schema
|
|
|
|
### Payload Structure (JSON)
|
|
|
|
```json
|
|
{
|
|
"id": "string (UUID)",
|
|
"dataname": "string",
|
|
"payload_type": "string",
|
|
"transport": "string",
|
|
"encoding": "string",
|
|
"size": "integer",
|
|
"data": "string or URL",
|
|
"metadata": "object"
|
|
}
|
|
```
|
|
|
|
### Payload Field Definitions
|
|
|
|
| Field | Type | Required | Validation | Description |
|
|
|-------|------|----------|------------|-------------|
|
|
| `id` | `string` | Yes | UUID v4 format | Unique identifier for this payload |
|
|
| `dataname` | `string` | Yes | Non-empty string | Name of the payload (e.g., `login_image`, `user_data`) |
|
|
| `payload_type` | `string` | Yes | Enum | Type of payload (see `payload_type` enum) |
|
|
| `transport` | `string` | Yes | Enum | Transport method: `direct` or `link` |
|
|
| `encoding` | `string` | Yes | Enum | Encoding method (see `encoding` enum) |
|
|
| `size` | `integer` | Yes | Positive integer | Size of the payload in bytes |
|
|
| `data` | `string` or `URL` | Yes | Base64 string or URL | Payload data (base64 for direct, URL for link) |
|
|
| `metadata` | `object` | No | Any JSON object | Payload-level metadata |
|
|
|
|
---
|
|
|
|
## Payload Format
|
|
|
|
### Tuple Format for `smartsend()`
|
|
|
|
The `smartsend()` function accepts data as an array of tuples with the format:
|
|
|
|
```
|
|
("data_name", data, "data_type")
|
|
```
|
|
|
|
| Position | Type | Description | Example |
|
|
|----------|------|-------------|---------|
|
|
| 1 | `string` | Data name - identifier for the payload | `"msg"`, `"login_image"`, `"user_data"` |
|
|
| 2 | `any` | Actual data - content to be serialized | `"Hello"`, `{"key": "value"}`, `DataFrame(...)` |
|
|
| 3 | `string` | Data type - must be in `payload_type` enum | `"text"`, `"dictionary"`, `"arrowtable"` |
|
|
|
|
### Single Payload Example
|
|
|
|
```julia
|
|
# Julia
|
|
smartsend("/chat/user/v1/message", [("msg", "Hello World", "text")])
|
|
```
|
|
|
|
```python
|
|
# Python
|
|
await smartsend("/chat/user/v1/message", [("msg", "Hello World", "text")])
|
|
```
|
|
|
|
```typescript
|
|
// JavaScript
|
|
await smartsend("/chat/user/v1/message", [["msg", "Hello World", "text"]]);
|
|
```
|
|
|
|
### Multiple Payloads Example
|
|
|
|
```julia
|
|
# Julia - Mixed text and binary data
|
|
data = [
|
|
("msg", "Hello", "text"),
|
|
("img", binary_data, "image")
|
|
]
|
|
smartsend("/agent/v1/process", data)
|
|
```
|
|
|
|
```python
|
|
# Python - Mixed types
|
|
data = [
|
|
("msg", "Hello", "text"),
|
|
("img", binary_data, "image")
|
|
]
|
|
await smartsend("/agent/v1/process", data)
|
|
```
|
|
|
|
### Data Type Mapping
|
|
|
|
| Platform | Input Type | Data Type String |
|
|
|----------|------------|------------------|
|
|
| All | `String` | `"text"` |
|
|
| All | `Dict`/`Object` | `"dictionary"` |
|
|
| Desktop | `DataFrame` | `"arrowtable"` or `"jsontable"` |
|
|
| All | `Array` of objects | `"jsontable"` |
|
|
| All | `Uint8Array`/`Buffer`/`bytes` | `"binary"` |
|
|
| Desktop | `Arrow.Table` | `"arrowtable"` |
|
|
| All | Image/Audio/Video binary | `"image"`, `"audio"`, `"video"` |
|
|
|
|
---
|
|
|
|
## Enumerations
|
|
|
|
### `msg_purpose` Enum
|
|
|
|
| Value | Description |
|
|
|-------|-------------|
|
|
| `ACK` | Acknowledgment of successful message processing |
|
|
| `NACK` | Negative acknowledgment of message processing failure |
|
|
| `updateStatus` | Status update message |
|
|
| `shutdown` | Graceful shutdown request |
|
|
| `chat` | Chat/message payload |
|
|
| `command` | Command payload |
|
|
| `event` | Event payload |
|
|
|
|
### `payload_type` Enum
|
|
|
|
| Value | Description | Supported Platforms | Encoding Options |
|
|
|-------|-------------|---------------------|------------------|
|
|
| `text` | Plain text string | All | `base64` |
|
|
| `dictionary` | JSON object/dictionary | All | `base64`, `json` |
|
|
| `arrowtable` | Apache Arrow IPC table | Desktop (Julia/JS/Python) | `base64`, `arrow-ipc` |
|
|
| `jsontable` | JSON array of objects | All | `base64`, `json` |
|
|
| `image` | Binary image data | All | `base64` |
|
|
| `audio` | Binary audio data | All | `base64` |
|
|
| `video` | Binary video data | All | `base64` |
|
|
| `binary` | Generic binary data | All | `base64` |
|
|
|
|
### `transport` Enum
|
|
|
|
| Value | Description | Data Format | Use Case |
|
|
|-------|-------------|-------------|----------|
|
|
| `direct` | Payload sent directly via NATS | Base64-encoded string | Payloads < size_threshold |
|
|
| `link` | Payload uploaded to file server | HTTP URL | Payloads ≥ size_threshold |
|
|
|
|
### `encoding` Enum
|
|
|
|
| Value | Description | Payload Types |
|
|
|-------|-------------|---------------|
|
|
| `none` | No additional encoding | Link transport URLs |
|
|
| `base64` | Base64 encoding | Text, binary, image, audio, video |
|
|
| `json` | JSON encoding | Dictionary, jsontable |
|
|
| `arrow-ipc` | Apache Arrow IPC format | Arrowtable |
|
|
|
|
---
|
|
|
|
## Transport Protocols
|
|
|
|
### Direct Transport Protocol
|
|
|
|
When `transport = "direct"`, the `data` field contains a Base64-encoded string of the serialized payload.
|
|
|
|
**Flow**:
|
|
1. Serialize payload according to `payload_type`
|
|
2. Encode serialized bytes as Base64
|
|
3. Include Base64 string in `data` field
|
|
|
|
**Example**:
|
|
```json
|
|
{
|
|
"transport": "direct",
|
|
"encoding": "base64",
|
|
"size": 11,
|
|
"data": "SGVsbG8gV29ybGQ="
|
|
}
|
|
```
|
|
|
|
### Link Transport Protocol
|
|
|
|
When `transport = "link"`, the `data` field contains a URL pointing to the uploaded payload.
|
|
|
|
**Flow**:
|
|
1. Serialize payload according to `payload_type`
|
|
2. Upload to HTTP file server (e.g., Plik)
|
|
3. Include returned URL in `data` field
|
|
|
|
**Example**:
|
|
```json
|
|
{
|
|
"transport": "link",
|
|
"encoding": "none",
|
|
"size": 1000000,
|
|
"data": "http://localhost:8080/file/3F62E/4AgGT/data.zip"
|
|
}
|
|
```
|
|
|
|
---
|
|
|
|
## Size Thresholds
|
|
|
|
### Desktop Platforms (Julia/JS/Python)
|
|
|
|
| Platform | Size Threshold | Notes |
|
|
|----------|----------------|-------|
|
|
| Desktop | 500,000 bytes (0.5MB) | Default threshold |
|
|
|
|
### MicroPython Platform
|
|
|
|
| Platform | Size Threshold | Maximum Payload | Notes |
|
|
|----------|----------------|-----------------|-------|
|
|
| MicroPython | 100,000 bytes (100KB) | 50,000 bytes | Hard limit due to memory constraints |
|
|
|
|
---
|
|
|
|
## NATS Subject Convention
|
|
|
|
### Subject Naming Pattern
|
|
|
|
```
|
|
<scope>/<service>/<version>/<operation>
|
|
```
|
|
|
|
**Examples**:
|
|
- `/agent/wine/api/v1/prompt` - AI agent prompt endpoint
|
|
- `/chat/user/v1/message` - User chat message
|
|
- `/system/worker/v1/status` - Worker status update
|
|
|
|
### Subject Wildcards
|
|
|
|
| Wildcard | Description | Example |
|
|
|----------|-------------|---------|
|
|
| `*` | Single-level wildcard | `/chat/user/v1/*` matches `/chat/user/v1/message` |
|
|
| `>` | Multi-level wildcard | `/chat/user/v1/>` matches all `/chat/user/v1/*` subjects |
|
|
|
|
---
|
|
|
|
## Error Handling
|
|
|
|
### Error Response Format
|
|
|
|
```json
|
|
{
|
|
"error": {
|
|
"code": "string",
|
|
"message": "string",
|
|
"details": "object"
|
|
}
|
|
}
|
|
```
|
|
|
|
### Error Codes
|
|
|
|
| Code | HTTP Status | Description | Recovery |
|
|
|------|-------------|-------------|----------|
|
|
| `INVALID_ENVELOPE` | 400 | Message envelope validation failed | Fix envelope structure |
|
|
| `INVALID_PAYLOAD_TYPE` | 400 | Unsupported payload type | Use supported payload_type |
|
|
| `INVALID_TRANSPORT` | 400 | Unsupported transport type | Use `direct` or `link` |
|
|
| `UPLOAD_FAILED` | 500 | File server upload failed | Retry or use direct transport |
|
|
| `DOWNLOAD_FAILED` | 503 | File server download failed | Retry with exponential backoff |
|
|
| `NATS_CONNECTION_FAILED` | 503 | NATS connection failed | Check NATS server availability |
|
|
| `DESERIALIZATION_ERROR` | 500 | Payload deserialization failed | Check payload_type matches data |
|
|
| `SIZE_EXCEEDED` | 413 | Payload exceeds maximum size | Split payload or use link transport |
|
|
|
|
### Exception Handling
|
|
|
|
| Scenario | Handler | Retry Policy |
|
|
|----------|---------|--------------|
|
|
| File server unavailable | Retry up to 5 times | Exponential backoff (100ms → 5000ms) |
|
|
| NATS publish failure | Connection auto-reconnect | TCP-level reconnection |
|
|
| Deserialization error | Log correlation ID and throw | No retry (data corruption) |
|
|
| Memory overflow (MicroPython) | Reject payloads >50KB | No retry (client-side check) |
|
|
|
|
---
|
|
|
|
## Serialization Rules
|
|
|
|
### Text Serialization
|
|
|
|
| Platform | Input Type | Serialization | Encoding |
|
|
|----------|------------|---------------|----------|
|
|
| All | `String` | UTF-8 bytes | Base64 |
|
|
|
|
### Dictionary Serialization
|
|
|
|
| Platform | Input Type | Serialization | Encoding |
|
|
|----------|------------|---------------|----------|
|
|
| All | `Object`/`Dict` | JSON string | Base64 or direct JSON |
|
|
|
|
### Arrow Table Serialization
|
|
|
|
| Platform | Input Type | Serialization | Encoding |
|
|
|----------|------------|---------------|----------|
|
|
| Desktop | `DataFrame` | Arrow IPC stream | Base64 or arrow-ipc |
|
|
| Desktop | `Arrow.Table` | Arrow IPC stream | Base64 or arrow-ipc |
|
|
| MicroPython | ❌ | Not supported | N/A |
|
|
|
|
### JSON Table Serialization
|
|
|
|
| Platform | Input Type | Serialization | Encoding |
|
|
|----------|------------|---------------|----------|
|
|
| All | `Vector{Dict}`/`Array<Object>` | JSON array | Base64 or direct JSON |
|
|
| Desktop | `pandas.DataFrame` | JSON array | Base64 or direct JSON |
|
|
|
|
### Binary Serialization
|
|
|
|
| Platform | Input Type | Serialization | Encoding |
|
|
|----------|------------|---------------|----------|
|
|
| All | `Uint8Array`/`Buffer`/`bytes` | Raw bytes | Base64 |
|
|
|
|
---
|
|
|
|
## API Contract
|
|
|
|
### `smartsend` Function Signature
|
|
|
|
#### Julia
|
|
|
|
```julia
|
|
function smartsend(
|
|
subject::String,
|
|
data::AbstractArray{Tuple{String, Any, String}};
|
|
broker_url::String = "nats://localhost:4222",
|
|
fileserver_url::String = "http://localhost:8080",
|
|
fileserver_upload_handler::Function = plik_oneshot_upload,
|
|
size_threshold::Int = 500_000,
|
|
correlation_id::String = string(uuid4()),
|
|
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,
|
|
msg_id::String = string(uuid4()),
|
|
sender_id::String = string(uuid4())
|
|
)::Tuple{msg_envelope_v1, String}
|
|
```
|
|
|
|
#### Python
|
|
|
|
```python
|
|
async def smartsend(
|
|
subject: str,
|
|
data: List[Tuple[str, Any, str]],
|
|
broker_url: str = "nats://localhost:4222",
|
|
fileserver_url: str = "http://localhost:8080",
|
|
fileserver_upload_handler: Callable = plik_oneshot_upload,
|
|
size_threshold: int = 500_000,
|
|
correlation_id: str = 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,
|
|
nats_connection: Any = None,
|
|
msg_id: str = None,
|
|
sender_id: str = None
|
|
) -> Tuple[Dict, str]:
|
|
```
|
|
|
|
#### JavaScript (Node.js)
|
|
|
|
```typescript
|
|
async function smartsend(
|
|
subject: string,
|
|
data: Array<[string, any, string]>,
|
|
options?: {
|
|
broker_url?: string;
|
|
fileserver_url?: string;
|
|
fileserver_upload_handler?: Function;
|
|
size_threshold?: number;
|
|
correlation_id?: string;
|
|
msg_purpose?: string;
|
|
sender_name?: string;
|
|
receiver_name?: string;
|
|
receiver_id?: string;
|
|
reply_to?: string;
|
|
reply_to_msg_id?: string;
|
|
is_publish?: boolean;
|
|
nats_connection?: NATS.Connection;
|
|
msg_id?: string;
|
|
sender_id?: string;
|
|
}
|
|
): Promise<[Object, string]>;
|
|
```
|
|
|
|
#### JavaScript (Browser)
|
|
|
|
```typescript
|
|
async function smartsend(
|
|
subject: string,
|
|
data: Array<[string, any, string]>,
|
|
options?: {
|
|
broker_url?: string;
|
|
fileserver_url?: string;
|
|
fileserver_upload_handler?: Function;
|
|
size_threshold?: number;
|
|
correlation_id?: string;
|
|
msg_purpose?: string;
|
|
sender_name?: string;
|
|
receiver_name?: string;
|
|
receiver_id?: string;
|
|
reply_to?: string;
|
|
reply_to_msg_id?: string;
|
|
is_publish?: boolean;
|
|
nats_connection?: NATS.Connection;
|
|
msg_id?: string;
|
|
sender_id?: string;
|
|
}
|
|
): Promise<[Object, string]>;
|
|
```
|
|
|
|
#### MicroPython
|
|
|
|
```python
|
|
def smartsend(
|
|
subject: str,
|
|
data: List[Tuple[str, Any, str]],
|
|
**kwargs
|
|
) -> Tuple[Dict, str]:
|
|
```
|
|
|
|
### `smartreceive` Function Signature
|
|
|
|
#### Julia
|
|
|
|
```julia
|
|
function smartreceive(
|
|
msg::NATS.Msg;
|
|
fileserver_download_handler::Function = _fetch_with_backoff,
|
|
max_retries::Int = 5,
|
|
base_delay::Int = 100,
|
|
max_delay::Int = 5000
|
|
)::JSON.Object{String, Any}
|
|
```
|
|
|
|
#### Python
|
|
|
|
```python
|
|
async def smartreceive(
|
|
msg: Any,
|
|
fileserver_download_handler: Callable = fetch_with_backoff,
|
|
max_retries: int = 5,
|
|
base_delay: int = 100,
|
|
max_delay: int = 5000
|
|
) -> Dict[str, Any]:
|
|
```
|
|
|
|
#### JavaScript (Node.js)
|
|
|
|
```typescript
|
|
async function smartreceive(
|
|
msg: Object,
|
|
options?: {
|
|
fileserver_download_handler?: Function;
|
|
max_retries?: number;
|
|
base_delay?: number;
|
|
max_delay?: number;
|
|
}
|
|
): Promise<Object>;
|
|
```
|
|
|
|
#### JavaScript (Browser)
|
|
|
|
```typescript
|
|
async function smartreceive(
|
|
msg: Object,
|
|
options?: {
|
|
fileserver_download_handler?: Function;
|
|
max_retries?: number;
|
|
base_delay?: number;
|
|
max_delay?: number;
|
|
}
|
|
): Promise<Object>;
|
|
```
|
|
|
|
#### MicroPython
|
|
|
|
```python
|
|
def smartreceive(msg: Any, **kwargs) -> Dict[str, Any]:
|
|
```
|
|
|
|
---
|
|
|
|
## File Server Interface
|
|
|
|
### Upload Handler Contract
|
|
|
|
**Function Signature**:
|
|
```julia
|
|
function fileserver_upload_handler(
|
|
file_server_url::String,
|
|
dataname::String,
|
|
data::Vector{UInt8}
|
|
)::Dict{String, Any}
|
|
```
|
|
|
|
**Return Format**:
|
|
```json
|
|
{
|
|
"status": 200,
|
|
"uploadid": "string",
|
|
"fileid": "string",
|
|
"url": "string"
|
|
}
|
|
```
|
|
|
|
**Required Keys**:
|
|
| Key | Type | Description |
|
|
|-----|------|-------------|
|
|
| `status` | `integer` | HTTP response status code |
|
|
| `uploadid` | `string` | Upload session identifier |
|
|
| `fileid` | `string` | File identifier within session |
|
|
| `url` | `string` | Full download URL |
|
|
|
|
### Download Handler Contract
|
|
|
|
**Function Signature**:
|
|
```julia
|
|
function fileserver_download_handler(
|
|
url::String,
|
|
max_retries::Int,
|
|
base_delay::Int,
|
|
max_delay::Int,
|
|
correlation_id::String
|
|
)::Vector{UInt8}
|
|
```
|
|
|
|
**Retry Policy**:
|
|
- Initial delay: `base_delay` milliseconds
|
|
- Maximum delay: `max_delay` milliseconds
|
|
- Multiplier: 2x per retry
|
|
- Maximum retries: `max_retries`
|
|
|
|
---
|
|
|
|
## Platform-Specific Constraints
|
|
|
|
### Desktop (Julia/JS/Python)
|
|
|
|
| Feature | Status | Notes |
|
|
|---------|--------|-------|
|
|
| Arrow IPC | ✅ Supported | Requires Arrow.jl/pyarrow |
|
|
| JSON table | ✅ Supported | Human-readable format |
|
|
| File server upload | ✅ Supported | HTTP/HTTPS |
|
|
| File server download | ✅ Supported | HTTP/HTTPS |
|
|
| Size threshold | 500KB | Configurable |
|
|
|
|
### MicroPython
|
|
|
|
| Feature | Status | Notes |
|
|
|---------|--------|-------|
|
|
| Arrow IPC | ❌ Not supported | Memory constraints |
|
|
| JSON table | ⚠️ Limited | Only direct transport |
|
|
| File server upload | ❌ Not implemented | Placeholder only |
|
|
| File server download | ❌ Not implemented | Placeholder only |
|
|
| Size threshold | 100KB | Hard limit enforced |
|
|
| Max payload | 50KB | Hard limit enforced |
|
|
|
|
---
|
|
|
|
## Message Flow
|
|
|
|
### Sending Flow
|
|
|
|
```mermaid
|
|
flowchart TD
|
|
A[User calls smartsend subject data] --> B[Serialize payload according to payload_type]
|
|
B --> C{Calculate serialized size}
|
|
C -->|Size < Threshold| D[Direct Transport: Encode as Base64]
|
|
C -->|Size >= Threshold| E[Link Transport: Upload to file server]
|
|
D --> F[Build envelope with metadata]
|
|
E --> F
|
|
F --> G[Convert envelope to JSON string]
|
|
G --> H[Publish to NATS subject]
|
|
H --> I[Return envelope and JSON string to caller]
|
|
|
|
style A fill:#f9f9f9,stroke:#333
|
|
style I fill:#e0e7ff,stroke:#3b82f6
|
|
style D fill:#d1fae5,stroke:#10b981
|
|
style E fill:#fef3c7,stroke:#f59e0b
|
|
```
|
|
|
|
### Receiving Flow
|
|
|
|
```mermaid
|
|
flowchart TD
|
|
A[NATS message arrives] --> B[Parse JSON envelope]
|
|
B --> C[For each payload: Check transport type]
|
|
C -->|transport == direct| D[Direct Transport: Extract Base64]
|
|
C -->|transport == link| E[Link Transport: Fetch from URL]
|
|
D --> F[Decode Base64]
|
|
E --> G[Fetch with exponential backoff]
|
|
F --> H[Deserialize based on payload_type]
|
|
G --> H
|
|
H --> I[Build payloads array]
|
|
I --> J[Replace payloads array with deserialized tuples]
|
|
J --> K[Return envelope with processed payloads]
|
|
|
|
style A fill:#f9f9f9,stroke:#333
|
|
style K fill:#e0e7ff,stroke:#3b82f6
|
|
style D fill:#d1fae5,stroke:#10b981
|
|
style E fill:#fef3c7,stroke:#f59e0b
|
|
```
|
|
|
|
---
|
|
|
|
## Validation Rules
|
|
|
|
### Envelope Validation
|
|
|
|
| Rule | Condition | Error Code |
|
|
|------|-----------|------------|
|
|
| Required fields present | `correlation_id`, `msg_id`, `timestamp`, `send_to`, `payloads` | `INVALID_ENVELOPE` |
|
|
| Valid UUID format | `correlation_id`, `msg_id`, `sender_id`, `receiver_id` | `INVALID_ENVELOPE` |
|
|
| Valid timestamp format | ISO 8601 UTC | `INVALID_ENVELOPE` |
|
|
| Non-empty payloads array | `length(payloads) > 0` | `INVALID_ENVELOPE` |
|
|
|
|
### Payload Validation
|
|
|
|
| Rule | Condition | Error Code |
|
|
|------|-----------|------------|
|
|
| Valid payload_type | Must be in `payload_type` enum | `INVALID_PAYLOAD_TYPE` |
|
|
| Valid transport | Must be `direct` or `link` | `INVALID_TRANSPORT` |
|
|
| Valid encoding | Must match payload_type and transport | `INVALID_TRANSPORT` |
|
|
| Positive size | `size > 0` | `INVALID_PAYLOAD` |
|
|
| Valid Base64 for direct | `data` matches Base64 pattern | `DESERIALIZATION_ERROR` |
|
|
| Valid URL for link | `data` matches HTTP(S) URL pattern | `DOWNLOAD_FAILED` |
|
|
|
|
---
|
|
|
|
## Test Contracts
|
|
|
|
### Unit Test Validation
|
|
|
|
| Test | Input | Expected Output | Notes |
|
|
|------|-------|-----------------|-------|
|
|
| Text round-trip | `("msg", "Hello", "text")` | `("msg", "Hello", "text")` | String serialization |
|
|
| Dictionary round-trip | `("data", {"key": "value"}, "dictionary")` | `("data", {"key": "value"}, "dictionary")` | JSON object round-trip |
|
|
| Arrow table round-trip | `("table", arrow_table_data, "arrowtable")` | `("table", arrow_table_data, "arrowtable")` | Arrow IPC round-trip |
|
|
| JSON table round-trip | `("table", [{"a":1},{"b":2}], "jsontable")` | `("table", [{"a":1},{"b":2}], "jsontable")` | JSON array of objects |
|
|
| Mixed payloads | `[("msg", "Hello", "text"), ("imgname", bytes, "binary")]` | `[("msg", "Hello", "text"), ("imgname", bytes, "binary")]` | Multiple payload types |
|
|
| Large payload | `("data", rand(10_000_000), "arrowtable")` | `("data", URL, "arrowtable")` with link transport | File server upload |
|
|
|
|
**Platform-Specific Notes:**
|
|
- **Julia**: Use `Dict`, `Vector{Dict}`, or convert `DataFrame` to dictionary for testing
|
|
- **Python**: Use `dict`, `list[dict]`, or convert `pandas.DataFrame` to dictionary for testing
|
|
- **JavaScript**: Use plain objects `{}` and arrays `[]`
|
|
- **MicroPython**: Use plain `dict` and `list` (limited to JSON table and text types)
|
|
|
|
### Integration Test Scenarios
|
|
|
|
| Scenario | Platforms | Payloads | Size Mix | Transport | Expected Result |
|
|
|----------|-----------|----------|----------|-----------|-----------------|
|
|
| Single text (small) | All | `text` | Small | direct | Round-trip successful |
|
|
| Single dictionary (small) | All | `dictionary` | Small | direct | Round-trip successful |
|
|
| Single arrow table (small) | Julia/JS/Python | `arrowtable` | Small | direct | Arrow IPC round-trip |
|
|
| Single JSON table (small) | All | `jsontable` | Small | direct | Dictionary array round-trip |
|
|
| Single text (large) | All | `text` | Large | link | File server upload/download |
|
|
| Single JSON table (large) | All | `jsontable` | Large | link | File server upload/download |
|
|
| Mixed payloads (small) | All | `text` + `dictionary` + `image` | All small | direct | All payloads preserved |
|
|
| Mixed payloads (large) | All | `text` + `dictionary` + `image` | All large | link | All payloads via file server |
|
|
| Mixed payloads (combo) | All | `text` (small) + `image` (large) | Mixed | direct/link | Correct transport per payload |
|
|
| Cross-platform JSON table | All | `jsontable` | Small | direct | Dictionary array round-trip |
|
|
| MicroPython ↔ Desktop | MicroPython ↔ Desktop | `text`/`dictionary` | Small | direct | Limited payload types |
|
|
| Desktop ↔ Desktop (all combos) | Julia↔JS↔Python | All types | Small/Large | direct/link | Full compatibility |
|
|
|
|
---
|
|
|
|
## Dependencies
|
|
|
|
### Required Dependencies by Platform
|
|
|
|
| Platform | Package | Version | Purpose |
|
|
|----------|---------|---------|---------|
|
|
| Julia | NATS.jl | Latest | NATS client |
|
|
| Julia | JSON.jl | Latest | JSON serialization |
|
|
| Julia | Arrow.jl | Latest | Arrow IPC support |
|
|
| Julia | HTTP.jl | Latest | HTTP file server |
|
|
| Julia | UUIDs.jl | Latest | UUID generation |
|
|
| Node.js | nats | Latest | NATS client |
|
|
| Node.js | node-fetch | Latest | HTTP file server |
|
|
| Python | nats-py | Latest | NATS client |
|
|
| Python | aiohttp | Latest | HTTP file server |
|
|
| Python | pyarrow | Latest | Arrow IPC support |
|
|
| MicroPython | builtin | N/A | Limited implementation |
|
|
|
|
### Optional Dependencies
|
|
|
|
| Platform | Package | Purpose |
|
|
|----------|---------|---------|
|
|
| Julia | DataFrames.jl | DataFrame support |
|
|
| Python | pandas | DataFrame support |
|
|
|
|
---
|
|
|
|
## Change Log
|
|
|
|
| Date | Version | Changes |
|
|
|------|---------|---------|
|
|
| 2026-03-13 | 1.0.0 | Initial specification |
|
|
| - | - | Message envelope schema defined |
|
|
| - | - | Payload schema with transport modes |
|
|
| - | - | Enumerations for payload_type, transport, encoding |
|
|
| - | - | Size thresholds for desktop/MicroPython |
|
|
| - | - | Error codes and validation rules |
|
|
| - | - | API contracts for all platforms |
|
|
|
|
---
|
|
|
|
## References
|
|
|
|
- [`docs/requirements.md`](./requirements.md) - Business requirements and user stories
|
|
- [`docs/architecture.md`](./architecture.md) - System architecture diagrams
|
|
- [`docs/implementation.md`](./implementation.md) - Implementation details
|
|
- [`src/NATSBridge.jl`](../src/NATSBridge.jl) - Ground truth implementation
|
|
- [`README.md`](../README.md) - Project overview
|
|
|
|
---
|
|
|
|
## Appendix
|
|
|
|
### A. Complete JSON Schema
|
|
|
|
```json
|
|
{
|
|
"$schema": "http://json-schema.org/draft-07/schema#",
|
|
"title": "NATSBridge Envelope",
|
|
"type": "object",
|
|
"properties": {
|
|
"correlation_id": {
|
|
"type": "string",
|
|
"pattern": "^[0-9A-F]{8}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{12}$",
|
|
"description": "UUID v4 format for tracking message flow"
|
|
},
|
|
"msg_id": {
|
|
"type": "string",
|
|
"pattern": "^[0-9A-F]{8}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{12}$",
|
|
"description": "Unique message identifier"
|
|
},
|
|
"timestamp": {
|
|
"type": "string",
|
|
"pattern": "^\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}\\.\\d{3}Z$",
|
|
"description": "ISO 8601 UTC timestamp"
|
|
},
|
|
"send_to": {
|
|
"type": "string",
|
|
"minLength": 1,
|
|
"description": "NATS subject to publish to"
|
|
},
|
|
"msg_purpose": {
|
|
"type": "string",
|
|
"enum": ["ACK", "NACK", "updateStatus", "shutdown", "chat", "command", "event"],
|
|
"description": "Purpose of the message"
|
|
},
|
|
"sender_name": {
|
|
"type": "string",
|
|
"minLength": 1,
|
|
"description": "Sender application name"
|
|
},
|
|
"sender_id": {
|
|
"type": "string",
|
|
"pattern": "^[0-9A-F]{8}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{12}$",
|
|
"description": "Sender UUID"
|
|
},
|
|
"receiver_name": {
|
|
"type": "string",
|
|
"description": "Receiver name (empty = broadcast)"
|
|
},
|
|
"receiver_id": {
|
|
"type": "string",
|
|
"pattern": "^[0-9A-F]{8}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{12}$|^$",
|
|
"description": "Receiver UUID (empty = broadcast)"
|
|
},
|
|
"reply_to": {
|
|
"type": "string",
|
|
"description": "Topic for reply messages"
|
|
},
|
|
"reply_to_msg_id": {
|
|
"type": "string",
|
|
"description": "Message ID being replied to"
|
|
},
|
|
"broker_url": {
|
|
"type": "string",
|
|
"pattern": "^nats://[^\\s]+$",
|
|
"description": "NATS broker URL"
|
|
},
|
|
"metadata": {
|
|
"type": "object",
|
|
"description": "Message-level metadata"
|
|
},
|
|
"payloads": {
|
|
"type": "array",
|
|
"minItems": 1,
|
|
"items": {
|
|
"$ref": "#/definitions/Payload"
|
|
}
|
|
}
|
|
},
|
|
"required": ["correlation_id", "msg_id", "timestamp", "send_to", "msg_purpose", "sender_name", "sender_id", "receiver_name", "receiver_id", "reply_to", "reply_to_msg_id", "broker_url", "payloads"],
|
|
"definitions": {
|
|
"Payload": {
|
|
"type": "object",
|
|
"properties": {
|
|
"id": {
|
|
"type": "string",
|
|
"pattern": "^[0-9A-F]{8}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{12}$"
|
|
},
|
|
"dataname": {
|
|
"type": "string",
|
|
"minLength": 1
|
|
},
|
|
"payload_type": {
|
|
"type": "string",
|
|
"enum": ["text", "dictionary", "arrowtable", "jsontable", "image", "audio", "video", "binary"]
|
|
},
|
|
"transport": {
|
|
"type": "string",
|
|
"enum": ["direct", "link"]
|
|
},
|
|
"encoding": {
|
|
"type": "string",
|
|
"enum": ["none", "base64", "json", "arrow-ipc"]
|
|
},
|
|
"size": {
|
|
"type": "integer",
|
|
"minimum": 1
|
|
},
|
|
"data": {
|
|
"anyOf": [
|
|
{
|
|
"type": "string",
|
|
"pattern": "^(https?://[^\\s]+)$"
|
|
},
|
|
{
|
|
"type": "string",
|
|
"pattern": "^[A-Za-z0-9+/]+=*$"
|
|
}
|
|
]
|
|
},
|
|
"metadata": {
|
|
"type": "object"
|
|
}
|
|
},
|
|
"required": ["id", "dataname", "payload_type", "transport", "encoding", "size", "data"]
|
|
}
|
|
}
|
|
}
|
|
```
|
|
|
|
### B. AsyncAPI Specification (NATS)
|
|
|
|
```yaml
|
|
asyncapi: '2.6.0'
|
|
info:
|
|
title: NATSBridge API
|
|
version: '1.0.0'
|
|
description: Cross-platform bi-directional data bridge using NATS
|
|
contact:
|
|
name: NATSBridge Team
|
|
url: https://github.com/your-org/NATSBridge
|
|
license:
|
|
name: MIT
|
|
url: https://opensource.org/licenses/MIT
|
|
channels:
|
|
/agent/{service}/api/v{version}/{operation}:
|
|
address: /agent/{service}/api/v{version}/{operation}
|
|
parameters:
|
|
service:
|
|
schema:
|
|
type: string
|
|
version:
|
|
schema:
|
|
type: string
|
|
enum: ['v1']
|
|
operation:
|
|
schema:
|
|
type: string
|
|
publish:
|
|
summary: Publish message to NATS
|
|
operationId: publishMessage
|
|
message:
|
|
$ref: '#/components/message'
|
|
subscribe:
|
|
summary: Subscribe to NATS messages
|
|
operationId: subscribeMessage
|
|
message:
|
|
$ref: '#/components/message'
|
|
components:
|
|
message:
|
|
payload:
|
|
$ref: '#/components/schemas/Envelope'
|
|
schemas:
|
|
Envelope:
|
|
type: object
|
|
properties:
|
|
correlation_id:
|
|
type: string
|
|
format: uuid
|
|
msg_id:
|
|
type: string
|
|
format: uuid
|
|
timestamp:
|
|
type: string
|
|
format: date-time
|
|
send_to:
|
|
type: string
|
|
msg_purpose:
|
|
type: string
|
|
enum: [ACK, NACK, updateStatus, shutdown, chat, command, event]
|
|
sender_name:
|
|
type: string
|
|
sender_id:
|
|
type: string
|
|
format: uuid
|
|
receiver_name:
|
|
type: string
|
|
receiver_id:
|
|
type: string
|
|
format: uuid
|
|
reply_to:
|
|
type: string
|
|
reply_to_msg_id:
|
|
type: string
|
|
broker_url:
|
|
type: string
|
|
metadata:
|
|
type: object
|
|
payloads:
|
|
type: array
|
|
items:
|
|
$ref: '#/components/schemas/Payload'
|
|
required:
|
|
- 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
|
|
- payloads
|
|
Payload:
|
|
type: object
|
|
properties:
|
|
id:
|
|
type: string
|
|
format: uuid
|
|
dataname:
|
|
type: string
|
|
payload_type:
|
|
type: string
|
|
enum: [text, dictionary, arrowtable, jsontable, image, audio, video, binary]
|
|
transport:
|
|
type: string
|
|
enum: [direct, link]
|
|
encoding:
|
|
type: string
|
|
enum: [none, base64, json, arrow-ipc]
|
|
size:
|
|
type: integer
|
|
minimum: 1
|
|
data:
|
|
type: string
|
|
metadata:
|
|
type: object
|
|
required:
|
|
- id
|
|
- dataname
|
|
- payload_type
|
|
- transport
|
|
- encoding
|
|
- size
|
|
- data
|
|
```
|
|
|
|
---
|
|
|
|
*This specification is versioned and maintained in git alongside the codebase. All implementations must adhere to this specification.*
|