A2A: A .NET implementation of the Google A2A protocol

Interact with agents using the A2A protocol in .NET applications. This library is designed to be used with ASP.NET Core applications and provides a simple way to add A2A support to your agents.

Status

This library has implemented the majority of the protocol v0.2.1, however there are likely some scenarios that are still not complete. The biggest piece of functionality that is missing is client callbacks using push notifications.

Overview

Library: A2A

This library contains the core A2A protocol implementation. It includes the following classes:

• A2AClient: Used for making A2A requests to an agent.
• TaskManager: Provides standardized support for managing tasks and task execution.
• ITaskStore: An interface for abstracting the storage of tasks. InMemoryTaskStore is a simple in-memory implementation.

Library: A2A.AspNetCore

This library adds the MapA2A extension method that allows you to add A2A support to an Agent hosted at the specified path.

var echoAgent = new EchoAgent();
var echoTaskManager = new TaskManager();
echoAgent.Attach(echoTaskManager);
app.MapA2A(echoTaskManager,"/echo");

Agent Integration Example

Each agent instance should be given its own TaskManager instance. The TaskManager is responsible for managing the tasks and their execution. It is an implementation decision as to whether a single agent instance processes many tasks or whether an agent instance is created for each task.

using A2A;

public class EchoAgent
{
    private TaskManager? _TaskManager;

    public void Attach(TaskManager taskManager)
    {
        _TaskManager = taskManager;
        taskManager.OnTaskCreated = ExecuteAgentTask;
        taskManager.OnTaskUpdated = ExecuteAgentTask;
    }

    public async Task ExecuteAgentTask(AgentTask task) {
        if  (_TaskManager == null) {
            throw new Exception("TaskManager is not attached.");
        }
        // Set Status to working
        await _TaskManager.UpdateStatusAsync(task.Id, TaskState.Working);

        var message = task.History!.Last().Parts.First().AsTextPart().Text;
        var artifact = new Artifact() {
            Parts = [new TextPart() {
                Text = $"Echo: {message}"
            }]
        };
        await _TaskManager.ReturnArtifactAsync(new TaskIdParams() {Id = task.Id}, artifact);
        await _TaskManager.UpdateStatusAsync(task.Id, TaskState.Completed, final: true);
    }
}