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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"WebFluxSseClientTransport/HttpClientSseClientTransport is unable to connect sse endpoint with custom prefix","articleBody":"**Bug description**\n\nhttps://github.com/modelcontextprotocol/java-sdk/blob/4eff00c8da01fffc830e166fa04d7b2a6463ff1c/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebFluxSseClientTransport.java#L78-L82\n\nIn mcp-spring-webflux 0.7.0, `SSE_ENDPOINT` is `\"/sse\"` and cannot be changed. When my MCP Server use an SSE url with custom prefix. For example, `{host}/sessions/f3a390a/sse` for sseEndpoint and `{host}/sessions/f3a390a/message` for messageEndpoint.  I have to set baseUri to  `/sessions/f3a390a` and messageEndpoint to `/message` according to `WebFluxSseClientTransport#sendMessage`:\n\nhttps://github.com/modelcontextprotocol/java-sdk/blob/4eff00c8da01fffc830e166fa04d7b2a6463ff1c/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebFluxSseClientTransport.java#L223-L225\n\nHowever, it is incompatible with `WebFluxSseServerTransport` (which allows custom prefixes)\n\n**Expected behavior**\n\nSupport scenarios like `sseEndpoint=/sessions/f3a390a/sse` and ~~`messageEndpoint=/sessions/f3a390a/sse`~~  `messageEndpoint=/sessions/f3a390a/message`\n\n","author":{"url":"https://github.com/feichao93","@type":"Person","name":"feichao93"},"datePublished":"2025-03-12T17:18:32.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":6},"url":"https://github.com/40/java-sdk/issues/40"}