Title: feat: implement MCP protocol version header support by tzolov · Pull Request #404 · modelcontextprotocol/java-sdk · GitHub
Open Graph Title: feat: implement MCP protocol version header support by tzolov · Pull Request #404 · modelcontextprotocol/java-sdk
X Title: feat: implement MCP protocol version header support by tzolov · Pull Request #404 · modelcontextprotocol/java-sdk
Description: Add MCP-Protocol-Version header to all HTTP requests as required by MCP specification 2025-06-18. This enables proper server-side version negotiation and backwards compatibility handling. Add protocol version constants (2025-06-18 for streamable HTTP, 2024-11-05 for SSE) Include MCP-Protocol-Version header in all GET/POST/DELETE requests Update WebClientStreamableHttpTransport, WebFluxSseClientTransport, HttpClientSseClientTransport, and HttpClientStreamableHttpTransport Complies with MCP specification requirement that HTTP clients MUST include protocol version header on all requests to MCP servers. Related to #398 , #363 , #250 Implementation Details: Added MCP_PROTOCOL_VERSION and MCP_PROTOCOL_VERSION_HEADER_NAME constants to all HTTP transport classes Uses protocol version 2025-06-18 for streamable HTTP transports (WebClientStreamableHttpTransport, HttpClientStreamableHttpTransport) Uses protocol version 2024-11-05 for SSE transports (WebFluxSseClientTransport, HttpClientSseClientTransport) for backwards compatibility Header is included in all HTTP requests (GET, POST, DELETE) across all transport implementations Specification Reference: MCP Specification - Protocol Version Header This change ensures full compliance with the MCP specification requirement that "the client MUST include the MCP-Protocol-Version HTTP header on all subsequent requests to the MCP server." Add MCP protocol version header support to all HTTP transport implementations as required by MCP specification 2025-06-18. Motivation and Context The MCP specification 2025-06-18 requires that HTTP clients MUST include the MCP-Protocol-Version header on all requests to MCP servers. This enables: Without this header, servers cannot properly handle version-specific behavior and may not function correctly with clients using different protocol versions. How Has This Been Tested? All existing unit tests pass with the changes HTTP requests now include the MCP-Protocol-Version header in all transport implementations Tested with both streamable HTTP transport (2025-06-18) and SSE transport (2024-11-05) scenarios Verified header is included in GET, POST, and DELETE requests across all affected transport classes Breaking Changes No breaking changes. This is a backwards-compatible addition: Existing client code continues to work without modification Only adds required headers to HTTP requests Servers that don't check for the header will continue to function normally Maintains backwards compatibility with older MCP protocol versions Types of changes Bug fix (non-breaking change which fixes an issue) New feature (non-breaking change which adds functionality) Breaking change (fix or feature that would cause existing functionality to change) Documentation update Checklist I have read the MCP Documentation My code follows the repository's style guidelines New and existing tests pass locally I have added appropriate error handling I have added or updated documentation as needed
Open Graph Description: Add MCP-Protocol-Version header to all HTTP requests as required by MCP specification 2025-06-18. This enables proper server-side version negotiation and backwards compatibility handling. Add prot...
X Description: Add MCP-Protocol-Version header to all HTTP requests as required by MCP specification 2025-06-18. This enables proper server-side version negotiation and backwards compatibility handling. Add prot...
Opengraph URL: https://github.com/modelcontextprotocol/java-sdk/pull/404
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