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44. Agent Communication Protocol (ACP)

Mini-Project: ACP: Two Different Agent Frameworks Interoperating

An ACP runtime that routes messages between a stateless function-based agent and a class-based stateful agent, demonstrating a multi-step clarification conversation across two different framework styles.

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What It Is

The Agent Communication Protocol (ACP) is an open protocol developed by IBM Research and BeeAI for enabling multi-agent communication. ACP uses a REST API model for server-to-server agent communication, supporting both synchronous and asynchronous patterns. Unlike A2A (focused on task delegation), ACP emphasizes message-based communication and is framework-agnostic (works with LangGraph, CrewAI, AutoGen, etc.).

Who Created It / Governed By

Created by IBM Research and the BeeAI community (2025). Open-source specification focused on interoperability between diverse agent frameworks.

How It Works

sequenceDiagram
    participant Agent1 as Agent A (Sender)
    participant ACP as ACP Runtime
    participant Agent2 as Agent B (Receiver)

    Agent1->>ACP: POST /agents (register)
    Agent2->>ACP: POST /agents (register)
    Agent1->>ACP: POST /runs (create run with message)
    ACP->>Agent2: Forward message
    Agent2-->>ACP: Response / stream
    ACP-->>Agent1: Result

Key Features

Feature Description
REST-Based Standard HTTP REST API (OpenAPI spec)
Agent Registration Agents register with metadata and capabilities
Runs Task execution unit with lifecycle management
Multimodal Supports text, files, and structured data
Async Support Both sync and async communication patterns
Framework Agnostic Works with any agent framework