@dexwox-labs/a2a-client
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TypeScript client implementation for Google's Agent-to-Agent (A2A) protocol - includes HTTP/WebSocket communication, circuit breakers and error handling
281 lines • 13 kB
JavaScript
;
/**
* @module MessageClient
* @description Client for sending and receiving messages between A2A agents
*/
var __esDecorate = (this && this.__esDecorate) || function (ctor, descriptorIn, decorators, contextIn, initializers, extraInitializers) {
function accept(f) { if (f !== void 0 && typeof f !== "function") throw new TypeError("Function expected"); return f; }
var kind = contextIn.kind, key = kind === "getter" ? "get" : kind === "setter" ? "set" : "value";
var target = !descriptorIn && ctor ? contextIn["static"] ? ctor : ctor.prototype : null;
var descriptor = descriptorIn || (target ? Object.getOwnPropertyDescriptor(target, contextIn.name) : {});
var _, done = false;
for (var i = decorators.length - 1; i >= 0; i--) {
var context = {};
for (var p in contextIn) context[p] = p === "access" ? {} : contextIn[p];
for (var p in contextIn.access) context.access[p] = contextIn.access[p];
context.addInitializer = function (f) { if (done) throw new TypeError("Cannot add initializers after decoration has completed"); extraInitializers.push(accept(f || null)); };
var result = (0, decorators[i])(kind === "accessor" ? { get: descriptor.get, set: descriptor.set } : descriptor[key], context);
if (kind === "accessor") {
if (result === void 0) continue;
if (result === null || typeof result !== "object") throw new TypeError("Object expected");
if (_ = accept(result.get)) descriptor.get = _;
if (_ = accept(result.set)) descriptor.set = _;
if (_ = accept(result.init)) initializers.unshift(_);
}
else if (_ = accept(result)) {
if (kind === "field") initializers.unshift(_);
else descriptor[key] = _;
}
}
if (target) Object.defineProperty(target, contextIn.name, descriptor);
done = true;
};
var __runInitializers = (this && this.__runInitializers) || function (thisArg, initializers, value) {
var useValue = arguments.length > 2;
for (var i = 0; i < initializers.length; i++) {
value = useValue ? initializers[i].call(thisArg, value) : initializers[i].call(thisArg);
}
return useValue ? value : void 0;
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.MessageClient = void 0;
const events_1 = require("events");
const a2a_core_1 = require("@dexwox-labs/a2a-core");
const a2a_core_2 = require("@dexwox-labs/a2a-core");
const error_handler_1 = require("./utils/error-handler");
const http_utils_1 = require("./utils/http-utils");
const task_client_1 = require("./task-client");
const agent_client_1 = require("./agent-client");
/**
* Client for sending and receiving messages between A2A agents
*
* The MessageClient provides methods for sending messages to agents and
* streaming real-time communication. It also provides access to related
* TaskClient and AgentClient instances for convenience.
*
* @example
* ```typescript
* const messageClient = new MessageClient({ baseUrl: 'https://a2a-server.example.com' });
*
* // Send a simple text message to an agent
* const messageId = await messageClient.sendMessage([
* { type: 'text', content: 'What is the weather in New York?' }
* ], 'weather-agent');
* ```
*/
let MessageClient = (() => {
let _classDecorators = [(0, a2a_core_1.TraceClass)()];
let _classDescriptor;
let _classExtraInitializers = [];
let _classThis;
let _classSuper = events_1.EventEmitter;
var MessageClient = class extends _classSuper {
static { _classThis = this; }
static {
const _metadata = typeof Symbol === "function" && Symbol.metadata ? Object.create(_classSuper[Symbol.metadata] ?? null) : void 0;
__esDecorate(null, _classDescriptor = { value: _classThis }, _classDecorators, { kind: "class", name: _classThis.name, metadata: _metadata }, null, _classExtraInitializers);
MessageClient = _classThis = _classDescriptor.value;
if (_metadata) Object.defineProperty(_classThis, Symbol.metadata, { enumerable: true, configurable: true, writable: true, value: _metadata });
__runInitializers(_classThis, _classExtraInitializers);
}
/** Configuration options for the client */
options;
/** Task client for managing tasks */
tasks;
/** Agent client for discovering and interacting with agents */
agents;
/**
* Creates a new MessageClient instance
* @param options - Configuration options for the client
*/
constructor(options) {
super();
this.options = {
timeout: 5000,
...options
};
this.tasks = new task_client_1.TaskClient(this.options);
this.agents = new agent_client_1.AgentClient(this.options);
}
/**
* Sends a message synchronously to an agent
*
* This method sends a message to a specified agent and waits for the server to
* acknowledge receipt. It validates the message parts before sending and handles
* network errors appropriately.
*
* @param parts - Array of message parts to send (text, file, data, etc.)
* @param agentId - ID of the target agent to receive the message
* @returns Promise resolving to the message ID assigned by the server
* @throws {A2ANetworkError} If there's a network issue contacting the server
* @throws {A2AValidationError} If the message parts are invalid
*
* @example
* ```typescript
* // Send a text message
* const textMessageId = await messageClient.sendMessage([
* { type: 'text', content: 'Hello, agent!' }
* ], 'assistant-agent');
*
* // Send a message with multiple parts
* const multipartMessageId = await messageClient.sendMessage([
* { type: 'text', content: 'Here is the data you requested' },
* {
* type: 'data',
* content: { temperature: 72, humidity: 65 },
* schema: 'weather-data'
* }
* ], 'weather-agent');
* ```
*/
async sendMessage(parts, agentId) {
(0, a2a_core_2.validateMessageParts)(parts);
const request = {
jsonrpc: '2.0',
method: 'sendMessage',
params: { parts, agentId }
};
try {
const response = await (0, http_utils_1.sendRequest)(this.options, request);
return response.result;
}
catch (err) {
if (err instanceof Error && err.message.includes('Network')) {
throw new error_handler_1.A2ANetworkError('Failed to send message', {
originalError: err,
agentId
});
}
throw (0, error_handler_1.normalizeError)(err);
}
}
/**
* Streams messages to and from an agent
*
* This method establishes a real-time streaming connection with an agent,
* allowing for continuous message exchange with automatic error handling.
*
* @param parts - Initial message parts to send to the agent
* @param agentId - ID of the target agent to stream with
* @param options - Configuration options and event handlers for the stream
* @param options.onMessage - Callback function for received messages
* @param options.onError - Optional callback function for stream errors
* @param options.onComplete - Optional callback function when stream completes
* @returns Promise that resolves when the stream completes
* @throws {A2ANetworkError} If there's a network issue establishing the stream
* @throws {A2AValidationError} If the message parts are invalid
*
* @example
* ```typescript
* await messageClient.streamMessage(
* [{ type: 'text', content: 'Tell me a story about dragons' }],
* 'storyteller-agent',
* {
* onMessage: (data) => console.log('Received:', data),
* onError: (error) => console.error('Stream error:', error),
* onComplete: () => console.log('Stream completed')
* }
* );
* ```
*/
async streamMessage(parts, agentId, options) {
const { maxRetries = 5, retryDelay = 1000, backoffFactor = 2, maxRetryDelay = 30000, heartbeatInterval = 10000, heartbeatTimeout = 30000, onMessage, onError, onComplete } = options;
let retryCount = 0;
let isStreaming = true;
let lastHeartbeat = Date.now();
const calculateDelay = (attempt) => {
const delay = retryDelay * Math.pow(backoffFactor, attempt);
return Math.min(delay, maxRetryDelay);
};
const handleEvent = (event) => {
try {
const data = JSON.parse(event.data);
if (data.type === 'heartbeat') {
lastHeartbeat = Date.now();
}
else {
if (data.type === 'taskUpdate' && this.tasks) {
this.tasks.handleTaskUpdate(data.task);
}
onMessage(data);
}
}
catch (err) {
onError?.(new Error('Failed to parse SSE event'));
}
};
const setupEventSource = () => {
const streamUrl = `${this.options.baseUrl}/stream?agentId=${agentId}`;
const eventSource = new EventSource(streamUrl);
eventSource.onmessage = handleEvent;
eventSource.onerror = (error) => {
eventSource.close();
isStreaming = false;
if (retryCount < maxRetries) {
const delay = calculateDelay(retryCount);
retryCount++;
setTimeout(doStream, delay);
}
else {
onError?.(new Error('Stream connection failed after retries'));
}
};
eventSource.addEventListener('close', () => {
isStreaming = false;
onComplete?.();
});
return eventSource;
};
const doStream = async () => {
const request = {
jsonrpc: '2.0',
method: 'streamMessage',
params: { parts, agentId }
};
try {
const response = await fetch(this.options.baseUrl, {
method: 'POST',
headers: {
'Content-Type': 'application/json',
...this.options.headers
},
body: JSON.stringify(request)
});
if (!response.ok)
throw new Error(`HTTP error! status: ${response.status}`);
if (!response.body)
throw new Error('No response body for streaming');
const eventSource = setupEventSource();
// Heartbeat monitoring
const heartbeatMonitor = setInterval(() => {
if (isStreaming && Date.now() - lastHeartbeat > heartbeatTimeout) {
eventSource.close();
onError?.(new Error('Heartbeat timeout exceeded'));
}
}, heartbeatInterval);
// Cleanup on completion
return new Promise((resolve) => {
eventSource.addEventListener('close', () => {
clearInterval(heartbeatMonitor);
resolve();
});
});
}
catch (err) {
if (err instanceof Error && err.message.includes('Network')) {
throw new error_handler_1.A2ANetworkError('Streaming connection failed', {
originalError: err,
agentId,
retryCount
});
}
throw (0, error_handler_1.normalizeError)(err);
}
};
return doStream();
}
};
return MessageClient = _classThis;
})();
exports.MessageClient = MessageClient;
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