A2A Message Types

Complete guide to message formats and communication standards

Message specifications designed for A2A Protocol implementation and research

Message Classification System

Core Interaction

REQUEST, RESPONSE, STREAM

Control Management

HANDSHAKE, HEARTBEAT, DISCONNECT

Data Transfer

UPLOAD, DOWNLOAD, SYNC

Event Notification

EVENT, ALERT, STATUS

Core Message Types

REQUEST Message

Initiates task execution or service request

{
  "message_type": "REQUEST",
  "request_id": "req_12345",
  "service": "data_processing",
  "parameters": {
    "input_data": "sample_data",
    "format": "json",
    "timeout": 30
  },
  "requirements": {
    "response_format": "json",
    "max_response_size": "10MB"
  }
}

RESPONSE Message

Returns results from processed request

{
  "message_type": "RESPONSE",
  "request_id": "req_12345",
  "status": "SUCCESS",
  "result": {
    "processed_data": "result_data",
    "execution_time": 15.2,
    "quality_score": 0.95
  },
  "metadata": {
    "agent_version": "1.0.0",
    "processing_method": "advanced_nlp"
  }
}

STREAM Message

Real-time data streaming for large datasets

{
  "message_type": "STREAM",
  "stream_id": "stream_789",
  "sequence": 42,
  "chunk_data": "base64_encoded_data",
  "stream_info": {
    "total_chunks": 100,
    "chunk_size": "1MB",
    "compression": "gzip"
  }
}

Smart Priority System

URGENT

Critical system messages

HIGH

Time-sensitive tasks

NORMAL

Standard operations

LOW

Background processes

Encoding Standards

Multiple Format Support

JSON

Human-readable, widely supported

Best for: Development, debugging

MessagePack

Binary format, 50% smaller

Best for: Production, performance

Protocol Buffers

Efficient, schema-based

Best for: Enterprise, scalability