Message Bindings | Fern Documentation

AsyncAPI 中的绑定允许您为服务器、通道、操作和消息指定协议特定信息。这使您能够为不同的消息协议提供详细配置。

asyncapi.yml

1 channels:
2   user/notifications:
3     address: user/notifications
4     messages:
5       UserNotification:
6         $ref: '#/components/messages/UserNotification'
7     bindings:
8       ws:
9         method: GET
10         query:
11           type: object
12           properties:
13             token:
14               type: string
15               description: Authentication token

WebSocket 绑定

为实时通信配置 WebSocket 特定设置：

asyncapi.yml

1 channels:
2   chat/room:
3     address: chat/room/{roomId}
4     bindings:
5       ws:
6         method: GET
7         headers:
8           type: object
9           properties:
10             Authorization:
11               type: string
12         query:
13           type: object
14           properties:
15             userId:
16               type: string
17             roomId:
18               type: string
19 
20 operations:
21   sendMessage:
22     action: send
23     channel:
24       $ref: '#/channels/chat~1room'
25     bindings:
26       ws:
27         type: request
28         method: message

MQTT 绑定

为 IoT 和消息应用程序配置 MQTT 特定设置：

asyncapi.yml

1 channels:
2   device/telemetry:
3     address: device/{deviceId}/telemetry
4     bindings:
5       mqtt:
6         qos: 1
7         retain: true
8         messageExpiryInterval: 3600
9         
10 servers:
11   mqtt-broker:
12     host: mqtt.example.com
13     protocol: mqtt
14     bindings:
15       mqtt:
16         clientId: device-client
17         cleanSession: false
18         keepAlive: 60
19         will:
20           topic: device/status
21           payload: "offline"
22           qos: 1
23           retain: true

Kafka 绑定

为高吞吐量事件流配置 Kafka 特定设置：

asyncapi.yml

1 channels:
2   user.events:
3     address: user.events
4     bindings:
5       kafka:
6         topic: user.events
7         partitions: 10
8         replicas: 3
9         topicConfiguration:
10           cleanup.policy: ["delete"]
11           retention.ms: 604800000
12           segment.ms: 86400000
13 
14 operations:
15   publishUserEvent:
16     action: send
17     channel:
18       $ref: '#/channels/user.events'
19     bindings:
20       kafka:
21         groupId: user-event-processors
22         key:
23           type: string
24           description: User ID for partitioning

服务器绑定

配置协议特定的服务器设置：

asyncapi.yml

1 servers:
2   websocket-server:
3     host: ws.example.com
4     protocol: wss
5     description: WebSocket server with SSL
6     bindings:
7       ws:
8         headers:
9           type: object
10           properties:
11             X-API-Version:
12               type: string
13               const: "v1"
14         
15   kafka-cluster:
16     host: kafka.example.com:9092
17     protocol: kafka
18     bindings:
19       kafka:
20         schemaRegistryUrl: https://schema-registry.example.com
21         schemaRegistryVendor: confluent

消息绑定

配置特定协议如何处理消息：

asyncapi.yml

1 components:
2   messages:
3     OrderEvent:
4       name: OrderEvent
5       contentType: application/json
6       payload:
7         $ref: '#/components/schemas/Order'
8       bindings:
9         kafka:
10           key:
11             type: string
12             description: Order ID for consistent partitioning
13           headers:
14             type: object
15             properties:
16               eventType:
17                 type: string
18                 enum: [created, updated, cancelled]
19         mqtt:
20           qos: 2
21           retain: false

HTTP 绑定

用于基于 HTTP 的协议，如 Server-Sent Events：

asyncapi.yml

1 channels:
2   events/stream:
3     address: /events/stream
4     bindings:
5       http:
6         type: response
7         method: GET
8         query:
9           type: object
10           properties:
11             lastEventId:
12               type: string
13               description: Last received event ID for resumption
14 
15 operations:
16   streamEvents:
17     action: send
18     channel:
19       $ref: '#/channels/events~1stream'
20     bindings:
21       http:
22         type: response
23         statusCode: 200
24         headers:
25           type: object
26           properties:
27             Content-Type:
28               type: string
29               const: text/event-stream

绑定提供了灵活性，可以利用协议特定功能，同时在不同传输机制之间维护统一的 API 规范。