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adding dynamic agent request handler
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‎package.json‎

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"coverage": "c8 npm run test",
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"generate": "curl https://raw.githubusercontent.com/google-a2a/A2A/refs/heads/main/specification/json/a2a.json > spec.json && node scripts/generateTypes.js && rm spec.json",
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"sample:cli": "tsx src/samples/cli.ts",
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"sample:movie-agent": "tsx src/samples/agents/movie-agent/index.ts"
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"sample:movie-agent": "tsx src/samples/agents/movie-agent/index.ts",
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"sample:dynamic-agents": "tsx src/samples/servers/dynamic_agents/index.ts",
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"sample:single_agent": "tsx src/samples/servers/single_agent/index.ts"
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},
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"dependencies": {
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"uuid": "^11.1.0"

‎src/samples/servers/dynamic_agents/README.md‎

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# Dynamic Agent Server
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This sample demonstrates how to use `DynamicAgentRequestHandler` to create a server that can dynamically route to different agents based on the URL path.
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The server provides two working example agents:
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- **Calculator Agent**: Performs basic math operations like "2 + 2" or "10 * 5"
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- **Weather Agent**: Provides fake weather data for major cities (London, Paris, Tokyo, New York, Sydney)
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## Running the Sample
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```bash
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npm run sample:dynamic-agents
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```
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The server will start on `http://localhost:3000`.
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## Available Endpoints
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- `GET /agents/calculator/.well-known/agent-card.json` - Calculator agent card
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- `POST /agents/calculator/` - Calculator agent messages
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- `GET /agents/weather/.well-known/agent-card.json` - Weather agent card
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- `POST /agents/weather/` - Weather agent messages
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## How It Works
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The `DynamicAgentRequestHandler` inspects the incoming URL and dynamically determines:
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1. Which agent card to return
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2. Which task store to use
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3. Which agent executor to run
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This allows a single route setup (`/agents`) to handle multiple different agent behaviors without needing separate route configurations for each agent.
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## Testing the Agents
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### Using the CLI Client
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The easiest way to test the agents is using the built-in CLI client:
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```bash
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# Test the calculator agent
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npm run sample:cli -- http://localhost:3000/agents/calculator/
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# Try typing: 1 + 1
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# Test the weather agent
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npm run sample:cli -- http://localhost:3000/agents/weather/
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# Try typing: whats weather in tokyo
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```
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### Using curl or HTTP clients
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You can also test the agents using curl or any HTTP client:
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```bash
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# Get calculator agent card
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curl http://localhost:3000/agents/calculator/.well-known/agent-card.json
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# Send a math problem to calculator
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curl -X POST http://localhost:3000/agents/calculator/ \
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-H "Content-Type: application/json" \
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-d '{
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"jsonrpc": "2.0",
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"method": "sendMessage",
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"params": {
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"message": {
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"messageId": "test-1",
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"role": "user",
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"parts": [{"kind": "text", "text": "What is 15 * 7?"}],
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"kind": "message"
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}
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},
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"id": 1
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}'
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# Ask weather agent about a city
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curl -X POST http://localhost:3000/agents/weather/ \
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-H "Content-Type: application/json" \
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-d '{
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"jsonrpc": "2.0",
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"method": "sendMessage",
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"params": {
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"message": {
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"messageId": "test-2",
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"role": "user",
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"parts": [{"kind": "text", "text": "What is the weather in Tokyo?"}],
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"kind": "message"
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}
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},
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"id": 2
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}'
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```
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## Key Benefits
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- **Single Route Setup**: One `setupRoutes()` call handles all agents
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- **Dynamic Routing**: URL inspection determines agent behavior
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- **Easy Extension**: Add new agents by updating resolver functions, no new routes needed
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- **Working Examples**: Both agents actually respond to messages with proper A2A protocol
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- **Clean API**: No need for complex route configuration

‎src/samples/servers/dynamic_agents/index.ts‎

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import express from 'express';
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import {
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DynamicAgentRequestHandler,
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RouteContext
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} from '../../../server/index.js';
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import { AgentCard, Message, TextPart } from '../../../types.js';
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import { InMemoryTaskStore } from '../../../server/store.js';
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import { AgentExecutor } from '../../../server/agent_execution/agent_executor.js';
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import { A2AExpressApp } from '../../../server/express/a2a_express_app.js';
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import { RequestContext } from '../../../server/agent_execution/request_context.js';
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import { ExecutionEventBus } from '../../../server/events/execution_event_bus.js';
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import { v4 as uuidv4 } from 'uuid';
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// Simple agent cards for calculator and weather
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const calculatorAgentCard: AgentCard = {
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name: 'Calculator Agent',
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description: 'Performs mathematical calculations',
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version: '1.0.0',
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protocolVersion: '2024-11-05',
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capabilities: {
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streaming: true,
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pushNotifications: false,
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},
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defaultInputModes: [],
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defaultOutputModes: [],
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skills: [],
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url: "http://localhost:3000/agents/calculator"
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};
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const weatherAgentCard: AgentCard = {
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name: 'Weather Agent',
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description: 'Provides weather information and forecasts',
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version: '1.0.0',
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protocolVersion: '2024-11-05',
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capabilities: {
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streaming: true,
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pushNotifications: false,
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},
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defaultInputModes: [],
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defaultOutputModes: [],
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skills: [],
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url: "http://localhost:3000/agents/weather"
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};
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// Calculator agent that performs basic math operations
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class CalculatorAgentExecutor implements AgentExecutor {
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async execute(requestContext: RequestContext, eventBus: ExecutionEventBus): Promise<void> {
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const userMessage = requestContext.userMessage;
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console.log(`Calculator processing: ${JSON.stringify(userMessage.parts)}`);
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// Extract text from user message
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const textParts = userMessage.parts.filter(part => part.kind === 'text');
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const userText = textParts.map(part => (part as TextPart).text).join(' ');
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// Simple calculation logic
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let result: string;
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try {
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// Look for basic math expressions
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const mathMatch = userText.match(/(\d+\.?\d*)\s*([\+\-\*\/])\s*(\d+\.?\d*)/);
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if (mathMatch) {
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const [, num1, operator, num2] = mathMatch;
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const a = parseFloat(num1);
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const b = parseFloat(num2);
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switch (operator) {
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case '+': result = `${a} + ${b} = ${a + b}`; break;
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case '-': result = `${a} - ${b} = ${a - b}`; break;
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case '*': result = `${a} × ${b} = ${a * b}`; break;
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case '/': result = b !== 0 ? `${a} ÷ ${b} = ${a / b}` : 'Error: Division by zero'; break;
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default: result = 'Unknown operation';
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}
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} else {
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result = "I can help you with basic math! Try asking me something like '2 + 2' or '10 * 5'.";
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}
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} catch (error) {
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result = 'Sorry, I had trouble understanding that math expression.';
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}
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// Create response message
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const responseMessage: Message = {
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kind: 'message',
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role: 'agent',
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messageId: uuidv4(),
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parts: [{ kind: 'text', text: result }],
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taskId: requestContext.taskId,
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contextId: userMessage.contextId,
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};
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// Publish the response
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eventBus.publish(responseMessage);
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eventBus.finished();
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}
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async cancelTask(taskId: string, eventBus: ExecutionEventBus): Promise<void> {
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console.log(`Canceling calculation task: ${taskId}`);
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eventBus.finished();
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}
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}
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// Weather agent that provides fake weather information
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class WeatherAgentExecutor implements AgentExecutor {
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async execute(requestContext: RequestContext, eventBus: ExecutionEventBus): Promise<void> {
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const userMessage = requestContext.userMessage;
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console.log(`Weather agent processing: ${JSON.stringify(userMessage.parts)}`);
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// Extract text from user message
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const textParts = userMessage.parts.filter(part => part.kind === 'text');
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const userText = textParts.map(part => (part as TextPart).text).join(' ').toLowerCase();
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// Simple weather response logic
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let result: string;
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const cities = ['london', 'paris', 'tokyo', 'new york', 'sydney'];
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const foundCity = cities.find(city => userText.includes(city));
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if (foundCity) {
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const temp = Math.floor(Math.random() * 30) + 5; // Random temp between 5-35°C
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const conditions = ['sunny', 'cloudy', 'rainy', 'partly cloudy'][Math.floor(Math.random() * 4)];
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result = `The weather in ${foundCity.charAt(0).toUpperCase() + foundCity.slice(1)} is currently ${temp}°C and ${conditions}. (This is fake data for demonstration purposes!)`;
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} else {
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result = "I can provide weather information! Try asking about the weather in London, Paris, Tokyo, New York, or Sydney.";
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}
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// Create response message
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const responseMessage: Message = {
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kind: 'message',
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role: 'agent',
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messageId: uuidv4(),
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parts: [{ kind: 'text', text: result }],
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taskId: requestContext.taskId,
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contextId: userMessage.contextId,
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};
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// Publish the response
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eventBus.publish(responseMessage);
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eventBus.finished();
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}
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async cancelTask(taskId: string, eventBus: ExecutionEventBus): Promise<void> {
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console.log(`Canceling weather task: ${taskId}`);
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eventBus.finished();
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}
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}
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// Create shared instances for persistence across requests
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const taskStore = new InMemoryTaskStore();
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const calculatorExecutor = new CalculatorAgentExecutor();
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const weatherExecutor = new WeatherAgentExecutor();
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// Create the dynamic request handler
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const dynamicHandler = new DynamicAgentRequestHandler(
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// Agent card resolver - determines which agent card to use based on route
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async (route: RouteContext) => {
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console.log(`Resolving agent card for route: ${route.url}`);
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// For other requests, check path segments
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if (route.url.includes('calculator')) {
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return calculatorAgentCard;
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} else if (route.url.includes('weather')) {
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return weatherAgentCard;
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}
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throw new Error("request for invalid agent");
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},
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// Task store resolver - same store instance for all agents to ensure persistence
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async (route: RouteContext) => {
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return taskStore;
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},
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// Agent executor resolver - returns singleton instances for efficiency
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async (route: RouteContext) => {
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console.log(`Resolving agent executor for route: ${route.url}`);
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if (route.url.includes('calculator')) {
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return calculatorExecutor;
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} else if (route.url.includes('weather')) {
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return weatherExecutor;
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}
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throw new Error("request for invalid agent");
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}
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);
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// Create the A2A Express app - dynamic routing is auto-detected from the handler
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const appBuilder = new A2AExpressApp(dynamicHandler);
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const app = appBuilder.setupRoutes(express(), '/agents');
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// Start the server
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const PORT = process.env.PORT || 3000;
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app.listen(PORT, () => {
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console.log(`🚀 Server started on http://localhost:${PORT}`);
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console.log('\nThe dynamic handler will route based on URL context.');
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console.log('Try accessing different URLs to see dynamic routing in action!');
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});
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// That's it! Simple and clean - just like the original A2A pattern.
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// The dynamic handler inspects the request context to determine routing.

‎src/samples/servers/restricted_agent/README.md‎

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# Restricted Agent Server
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This sample demonstrates how to create an A2A agent server that requires authorization via a special Authorization header. The agent will only respond to requests that include the correct Bearer token.
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## Features
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- **Authorization Required**: All requests must include a valid `Authorization: Bearer <token>` header
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- **Security**: Returns 401 for missing auth headers and 403 for invalid tokens
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- **Custom Request Handler**: Extends the default request handler to add authentication middleware
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- **Clear Error Messages**: Provides helpful error responses for unauthorized requests
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## Running the Server
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```bash
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npx tsx src/samples/servers/restricted_agent/index.ts
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```
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The server will start on `http://localhost:3000` and display the required authorization token.
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## Testing
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### With Valid Authorization (Success)
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```bash
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curl -H "Authorization: Bearer secret-auth-token-12345" \
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-H "Content-Type: application/json" \
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-X POST http://localhost:3000/agent/tasks \
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-d '{
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"message": {
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"kind": "message",
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"messageId": "test-msg-1",
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"role": "user",
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"parts": [{"kind": "text", "text": "Hello restricted agent!"}],
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"contextId": "test-context"
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}
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}'
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```
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### Without Authorization (Should Fail with 401)
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```bash
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curl -X POST http://localhost:3000/agent/tasks \
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-H "Content-Type: application/json" \
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-d '{
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"message": {
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"kind": "message",
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"messageId": "test-msg-1",
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"role": "user",
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"parts": [{"kind": "text", "text": "Hello!"}],
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"contextId": "test-context"
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}
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}'
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```
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### With Invalid Token (Should Fail with 403)
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```bash
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curl -H "Authorization: Bearer wrong-token" \
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-H "Content-Type: application/json" \
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-X POST http://localhost:3000/agent/tasks \
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-d '{
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"message": {
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"kind": "message",
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"messageId": "test-msg-1",
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"role": "user",
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"parts": [{"kind": "text", "text": "Hello!"}],
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"contextId": "test-context"
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}
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}'
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```
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## Implementation Details
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The sample creates a custom `AuthorizedRequestHandler` that extends the default `DefaultRequestHandler` and overrides the `handleRequest` method to check for proper authorization before allowing access to the agent.
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The required token is: `secret-auth-token-12345`
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## Security Notes
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- In production, use proper JWT tokens or OAuth2 flows
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- Store secrets securely (environment variables, secret managers)
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- Consider rate limiting and other security measures
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- Use HTTPS in production environments

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