This module, "MCP Communication: Message Formats and Transports," provides a foundational understanding of how the Model Context Protocol (MCP) facilitates communication between clients and servers.
A core component of MCP's architecture is the **transport layer**, which handles the actual exchange of messages. Transports are crucial for establishing and maintaining the communication channels over which MCP messages flow.
MCP leverages **JSON-RPC 2.0** for all message exchanges, defining specific message types to manage interactions:
* **Requests**: Messages sent from one party expecting a response from the other.
* **Responses (Results)**: Successful replies to requests, containing the requested data.
* **Errors**: Responses indicating that a request failed, providing a code and message.
* **Notifications**: One-way messages that do not expect a response, used for asynchronous updates or events.
The module details two primary built-in transport implementations:
1. **Stdio Transport**: Utilizes standard input/output streams for communication. This transport is ideal for **local processes** where clients and servers run on the same machine, offering efficient and straightforward inter-process communication.
2. **HTTP with SSE Transport**: Employs Server-Sent Events (SSE) for server-to-client messages and HTTP POST for client-to-server messages. This transport is suitable for **remote communication** scenarios, especially when HTTP compatibility is required, such as web-based clients or communication across networks.
Understanding these message formats and transport mechanisms is essential for developing robust and efficient MCP applications, allowing developers to select the most appropriate transport for their specific communication needs.
