Welcome to the "MCP Communication: Message Formats and Transports" module, a crucial step in your journey through the Model Context Protocol (MCP). As you learned in the "Core architecture" overview, seamless communication is at the heart of MCP, enabling clients and servers to exchange information efficiently. This module dives deep into the fundamental mechanisms that power this exchange.
Effective communication in any distributed system relies on two key elements: a standardized way to format messages and reliable channels to transport those messages. In MCP, these roles are fulfilled by the **JSON-RPC 2.0 message format** and a set of **built-in transport types**.
This module will demystify how MCP messages are structured and sent across different environments. You'll gain a comprehensive understanding of the various JSON-RPC message types—requests, responses, and notifications—that form the backbone of all MCP interactions. We will then explore the practical implementations of MCP's primary transport mechanisms: **Stdio (Standard Input/Output)**, ideal for local process communication, and **Server-Sent Events (SSE) over HTTP**, suitable for more complex client-server scenarios.
By the end of this module, you will be able to:
* **Understand the role of transports** in facilitating MCP communication.
* **Identify the different JSON-RPC message types** used by MCP (requests, responses, notifications).
* **Learn about the built-in Stdio and SSE transport implementations**.
* **Determine appropriate use cases** for Stdio and SSE transports, enabling you to choose the best communication method for your MCP applications.
Let's begin by unraveling the structure of MCP messages and the channels through which they travel.
