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Add skeleton for new websockets stream api docs #1074

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Original file line number Diff line number Diff line change
@@ -0,0 +1,184 @@
---
title: Flow Websockets Stream API Specification
sidebar_label: Websockets Stream API
sidebar_position: 3
---

# Flow Websockets Stream API Documentation

## Overview

The Stream API allows clients to receive real-time updates from the Flow blockchain via WebSocket connections. It
supports subscribing to various topics, such as blocks, events, and transactions, enabling low-latency access to live
data.

### Important Information

- **Endpoint**: The WebSocket server is available at:
```
wss://api.flow.com/ws
```
- **Limits**:
- Each connection supports up to 50 concurrent subscriptions. Exceeding this limit will result in an error.
- TODO: list all limits here
- **Supported Topics**:
- `blocks`
- `block_headers`
- `block_digests`
- `events`
- `transaction_statuses`
- `account_statuses`
- **Notes**: Always handle errors gracefully and close unused subscriptions to maintain efficient connections.

---

## Setting Up a WebSocket Connection

Use any WebSocket client library to connect to the endpoint. Below is an example using JavaScript:

```javascript
const ws = new WebSocket('wss://api.flow.com/ws');

ws.onopen = () => {
console.log('Connected to WebSocket server');
};

ws.onclose = () => {
console.log('Disconnected from WebSocket server');
};

ws.onerror = (error) => {
console.error('WebSocket error:', error);
};
```

---

## Subscribing to Topics

To receive data from a specific topic, send a subscription request in JSON format over the WebSocket connection.

### Request Format

```json
{
"subscription_id": "some-uuid-42",
"action": "subscribe",
"topic": "blocks",
"parameters": {
"start_block_height": "123456789"
}
}
```

- **`subscription_id`**: A unique identifier for the subscription (UUID string). If omitted, the server generates one.
- **`action`**: The action to perform. Supported actions include: `subscribe`, `unsubscribe`, `list_subscriptions`.
- **`topic`**: The topic to subscribe to. See the supported topics in the Overview.
- **`parameters`**: Additional parameters for subscriptions, such as `start_block_height`, `start_block_id`, and others.

### Response Format

```json
{
"subscription_id": "some-uuid-42",
"error": null
}
```

---

## Unsubscribing from Topics

To stop receiving data from a specific topic, send an unsubscribe request.

### Request Format

```json
{
"subscription_id": "some-uuid-42",
"action": "unsubscribe"
}
```

### Response Format

```json
{
"subscription_id": "some-uuid-42",
"error": null
}
```

---

## Listing Active Subscriptions

You can retrieve a list of all active subscriptions for the current WebSocket connection.

### Request Format

```json
{
"action": "list_subscriptions"
}
```

### Response Format

```json
{
"subscriptions": [
{
"subscription_id": "uuid-1",
"topic": "blocks",
"parameters": {
"start_block_height": "123456789"
}
},
{
"subscription_id": "uuid-2",
"topic": "events",
"parameters": {}
}
]
}
```

---

## Errors Example

If a request is invalid or cannot be processed, the server responds with an error message.

### OK Response

```json
{
"subscription_id": "some-uuid-42",
"payload": {
"id": "0x1234...",
"height:": "123456789",
"timestamp": "2025-01-02T10:00:00Z"
},
"error": null
}
```

### Error Response

```json
{
"subscription_id": "some-uuid-42",
"payload": null,
"error": {
"code": 500,
"message": "Access Node failed"
}
}
```

### Common Error Codes

- **400**: Invalid message format or parameters
- **404**: Subscription not found
- **500**: Internal server error
Original file line number Diff line number Diff line change
@@ -0,0 +1,48 @@
---
title: List subscriptions request message format
sidebar_label: Listing subscriptions
sidebar_position: 3
---

# List subscriptions message format

List subscriptions requests must be sent as JSON in text frames, one request per frame.
This message is different from other as it doesn't require you to provide subscription ID.
Thus, the response for this message is different too.

### Example of request

```json
{
"action": "list_subscriptions"
}
```

### Example of response

```json
{
"subscriptions": [
{
"subscription_id": "uuid-1",
"topic": "blocks",
"parameters": {
"start_block_height": "123456789"
}
},
{
"subscription_id": "uuid-2",
"topic": "events",
"parameters": {}
}
]
}
```

If there are no active subscriptions, `subscriptions` array will be empty.

### Request fields

| Name | Type | Mandatory | Description |
|----------|--------|-----------|-----------------------------------------------------------------------------------------|
| `action` | STRING | YES | Action to perform. Must be `list_subscriptions` to initiate a list subscription request |
Original file line number Diff line number Diff line change
@@ -0,0 +1,81 @@
---
title: Subscribe request message format
sidebar_label: Subscribing to topic
sidebar_position: 1
---

# Subscribe request format

Subscribe requests must be sent as JSON in text frames, one request per frame.

### Example of subscribe request

```json
{
"subscription_id": "fa770c92-a1f1-4375-9a7b-e13d9aac0786",
"action": "subscribe",
"topic": "block_digests",
"parameters": {
"start_block_height": "99,416,580"
}
}
```

### Example of successful response

```json
{
"subscription_id": "fa770c92-a1f1-4375-9a7b-e13d9aac0786"
}
```

### Example of failed response

```json
{
"subscription_id": "fa770c92-a1f1-4375-9a7b-e13d9aac0786",
"error": {
"code": 400,
"message": "invalid message"
}
}
```

### Example of messages provided by subscription (if successful)

```json
{
"subscription_id": "fa770c92-a1f1-4375-9a7b-e13d9aac0786",
"payload": {
"id": "0x1234...",
"height:": "123456789",
"timestamp": "2025-01-02T10:00:00Z"
}
}
```

### Example of messages provided by subscription (if error)

```json
{
"subscription_id": "fa770c92-a1f1-4375-9a7b-e13d9aac0786",
"error": {
"code": 500,
"message": "access node is not responsible"
}
}
```

### Request fields:

| Name | Type | Mandatory | Description |
|-------------------|--------|-----------|--------------------------------------------------------------------------------------------|
| `subscription_id` | UUID | NO | Optional unique identifier for the subscription. Server will generate one if omitted |
| `action` | STRING | YES | Action to perform. Must be `subscribe` to initiate a subscription |
| `topic` | STRING | YES | The topic to subscribe to, such as `blocks`, `block_digests`, etc. |
| `parameters` | STRING | NO | Additional parameters for the subscription, such as `start_block_id`, `start_block_height` |

You can use `subscription_id` as a client-generated identifier to track responses asynchronously.
If you don't provide `subscription_id`, the server will generate one and include it in the response.

The order of params is not significant.
Original file line number Diff line number Diff line change
@@ -0,0 +1,44 @@
---
title: Unsubscribe request message format
sidebar_label: Unsubscribing from topic
sidebar_position: 2
---

# Unsubscribe message format

Unsubscribe requests must be sent as JSON in text frames, one request per frame.

### Example of unsubscribe request

```json
{
"subscription_id": "fa770c92-a1f1-4375-9a7b-e13d9aac0786",
"action": "unsubscribe"
}
```

### Example of successful response

```json
{
"subscription_id": "fa770c92-a1f1-4375-9a7b-e13d9aac0786"
}
```

### Example of error response

```json
{
"error": {
"code": 404,
"message": "subscription not found"
}
}
```

### Request fields

| Name | Type | Mandatory | Description |
|-------------------|--------|-----------|-----------------------------------------------------------------------|
| `subscription_id` | UUID | YES | Unique identifier of the subscription |
| `action` | STRING | YES | Action to perform. Must be `unsubscribe` to initiate a unsubscription |
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