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Communication channels between MCP clients and servers

Core Idea: MCP (Model Context Protocol) supports different transport types that define how MCP clients communicate with MCP servers, with the primary options being SSE (Server-Sent Events) over HTTP/HTTPS and Standard I/O.

Key Elements

Transport Options

1. SSE (Server-Sent Events)

   • Runs over HTTP/HTTPS
   • Creates a stateful connection between the MCP client and server
   • Requires endpoint setup for both connection establishment and message exchange
   • Well-suited for web applications with server components

2. Standard I/O (stdio)

   • Uses system standard input/output streams for communication
   • Ideal for command-line interfaces and local tools
   • Enables direct integration with terminal-based AI assistants like Claude
   • No network configuration required

Implementation Considerations

• SSE Implementation:

  • Requires creating an Express (or similar) HTTP server
  • Needs two endpoints: one for establishing the connection (/sse) and another for exchanging messages (/sse/messages)
  • Maintains a persistent connection between client and server
  • Currently stateful, though stateless variants are in development

• Standard I/O Implementation:

  • Imports the StandardIOServerTransport from the Model Context Protocol SDK
  • Connects a server instance to this transport
  • Runs as a process that receives input from stdin and provides output via stdout
  • Can be configured in tools like Claude through their developer settings

Compatibility Considerations

• SSE works well for web applications needing to connect to MCP servers
• Standard I/O is preferred for CLI tools and integration with terminal-based AI assistants
• The same MCP server logic can be used with different transport types by abstracting the core functionality

Additional Connections

• Broader Context: Model Context Protocol (communication framework for AI tools)
• Applications: MCP Server Implementation (how to implement servers for different transports)
• See Also: WebSocket (alternative transport mechanism not covered in the material)

References

1. Blue Collar Coder video on Model Context Protocol implementation

#mcp #transport #sse #stdio #ai-tools

Connections:

Sources:

• From: Jack Herrington - Applied Model Context Protocol (MCP) In 20 Minutes