a2a-阿里云帮助中心

Calls the a2a operation to interact with OSS Agent through the A2A (Agent-to-Agent) protocol. This operation is based on JSON-RPC 2.0 and supports both streaming and non-streaming message sending modes.

Usage notes

This operation follows the A2A (Agent-to-Agent) protocol and is based on the JSON-RPC 2.0 specification.

Request syntax

POST /api/a2a HTTP/1.1

Request parameters

Parameter	Type	Required	Description
id	string	Yes	The message ID. Used to associate requests and responses. Example: `791`
jsonrpc	string	Yes	The JSON-RPC protocol version identifier. Fixed value: `2.0`.
method	string	Yes	The request method. Valid values: `message/stream`: Sends a message in streaming mode. The Agent returns a streaming response. `message/send`: Sends a message in non-streaming mode. The Agent returns a complete response.
params	object	Yes	The A2A request parameters. Contains the message content to be sent to the Agent.
params.message	object	Yes	The message object. Contains the role, content parts, and message type.
params.message.role	string	Yes	The message role. Example: `user`
params.message.parts	array<object>	Yes	The list of message content parts. Each part contains the `kind` (type, such as text) and `text` (text content) fields.
params.message.kind	string	Yes	The message type identifier. Fixed value: `message`.

Response parameters

The response follows the JSON-RPC 2.0 specification and returns a Task object that contains the task status, context information, and conversation history.

Parameter	Type	Description
jsonrpc	string	The JSON-RPC protocol version. Fixed value: `2.0`.
id	string	The response identifier that corresponds to the id in the request.
result	object	The Task object. Contains the task ID, context ID, status, artifacts, and conversation history.
result.id	string	The unique task identifier.
result.contextId	string	The context ID. Used to associate multiple interactions within the same session.
result.status	object	The task status. Contains the `state` (status value, such as submitted) and `timestamp` (timestamp) fields.
result.history	array<object>	The conversation history message list. Each message contains the role, parts, messageId, contextId, taskId, and other fields.
result.kind	string	The result object type. Fixed value: `task`.

Examples

Sample request:

POST /api/a2a HTTP/1.1
Content-Type: application/json

{
  "id": "791",
  "jsonrpc": "2.0",
  "method": "message/stream",
  "params": {
    "message": {
      "role": "user",
      "parts": [
        {
          "kind": "text",
          "text": "Hello"
        }
      ],
      "kind": "message"
    }
  }
}

Sample response:

{
  "jsonrpc": "2.0",
  "id": "791",
  "result": {
    "id": "UUID",
    "contextId": "UUID",
    "status": {
      "state": "submitted",
      "timestamp": "2026-08-20T00:00:00.000000000Z"
    },
    "artifacts": [],
    "history": [
      {
        "role": "user",
        "parts": [
          {
            "text": "Hello",
            "kind": "text"
          }
        ],
        "messageId": "msg-1",
        "contextId": "UUID",
        "taskId": "UUID.task-1",
        "metadata": {},
        "kind": "message"
      }
    ],
    "kind": "task"
  }
}