Streamable HTTP versus SSE, and why it is the new standard

The differences between SSE and Streamable HTTP are important to understand when choosing the right technology for your application.

There are some key distinctions. The first reason is that SSE in MCP is considered deprecated; you should be using Streamable HTTP instead.

So, why is there a chapter called SSE in this book? The reason is that this book is written for you as both a developer of MCP servers and also as a consumer of servers, where you might be writing a client toward an existing server that might be using SSE. In short, you should know how to deal with both types of transport due to there being legacy code that you might be asked to work with. In fact, the article at https://github.com/modelcontextprotocol/modelcontextprotocol/discussions/308 states that 20 reference servers, over 50 official integrations, and 186 community-developed servers and clients were using SSE when it was announced that it was...