basic

A2A Basic Example

This example demonstrates a basic implementation of the Agent-to-Agent (A2A) protocol using the trpc-a2a-go library. It consists of:

1. A versatile text processing agent server that supports multiple operations
2. A feature-rich CLI client that demonstrates all the core A2A protocol APIs

Server Features

The server is a text processing agent capable of:

• Processing text in various modes: reverse, uppercase, lowercase, word count
• Supporting both streaming and non-streaming responses
• Demonstrating multi-turn conversations with the input-required state
• Handling task cancellation
• Creating and streaming artifacts

Running the Server

cd server
go run main.go [options]

Server options:

• --host: Host address (default: localhost)
• --port: Port number (default: 8080)
• --desc: Custom agent description
• --no-cors: Disable CORS headers
• --no-stream: Disable streaming capability

Client Features

The client is a CLI application that connects to an A2A agent and provides:

• Support for both streaming and non-streaming modes
• Interactive CLI with command history
• Session management for contextual conversations
• Task management (create, cancel, get)
• Agent capability discovery

Running the Client

cd client
go run main.go [options]

Client options:

• --agent: Agent URL (default: http://localhost:8080/)
• --timeout: Request timeout (default: 60s)
• --no-stream: Disable streaming mode
• --session: Use specific session ID (generate new if empty)
• --use-tasks-get: Use tasks/get to fetch final state (default: true)
• --history: Number of history messages to request (default: 0)

Client Commands

Once the client is running, you can use the following commands:

• help: Show help message
• exit: Exit the program
• session [id]: Set or generate a new session ID
• mode [stream|sync]: Set interaction mode (streaming or standard)
• cancel [task-id]: Cancel a task
• get [task-id] [history]: Get task details
• card: Fetch and display the agent's capabilities card

For normal interaction, simply type your message and press Enter.

Text Processing Commands

The server understands the following text processing commands:

• reverse <text>: Reverses the input text
• uppercase <text>: Converts text to uppercase
• lowercase <text>: Converts text to lowercase
• count <text>: Counts words and characters in text
• multi: Start a multi-step interaction
• example: Demonstrates input-required state
• help: Shows the help message

Usage Example

1. Start the server:

   cd server
   go run main.go

2. In another terminal, start the client:

   cd client
   go run main.go

3. Try some commands:

   > help
   > reverse hello world
   > uppercase the quick brown fox
   > multi
   > card
   > mode sync
   > lowercase TESTING LOWERCASE
   

A2A Protocol Implementation

This example demonstrates the following A2A protocol features:

• Agent discovery via Agent Cards (/.well-known/agent.json)
• Task creation using tasks/send and tasks/sendSubscribe
• Task state retrieval using tasks/get
• Task cancellation using tasks/cancel
• Streaming updates for long-running tasks
• Multi-turn conversations using the input-required state
• Artifact generation and streaming

The implementation follows the A2A specification and provides a practical example of building interoperable AI agents using the protocol.