WebFluxSseClientTransport/HttpClientSseClientTransport is unable to connect sse endpoint with custom prefix

[feichao93]

Bug description

java-sdk/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebFluxSseClientTransport.java

Lines 78 to 82 in 4eff00c

	/**
	* Default SSE endpoint path as specified by the MCP transport specification. This
	* endpoint is used to establish the SSE connection with the server.
	*/
	private static final String SSE_ENDPOINT = "/sse";

In 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:

java-sdk/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebFluxSseClientTransport.java

Lines 223 to 225 in 4eff00c

	String jsonText = this.objectMapper.writeValueAsString(message);
	return webClient.post()
	.uri(messageEndpointUri)

However, it is incompatible with WebFluxSseServerTransport (which allows custom prefixes)

Expected behavior

Support scenarios like sseEndpoint=/sessions/f3a390a/sse and messageEndpoint=/sessions/f3a390a/sse messageEndpoint=/sessions/f3a390a/message

[wwulfric]

In my opinion, it's ok to use sessions/f3a390a as baseUri in your case.
I met the same problem in customizing sse endpoint in #41.
messageEndpoint doesn't seem necessary to be customized because the client should request /sse endpoint from the server and the server will respond with it

HTTP/1.1 200 OK
content-type: text/event-stream
cache-control: no-cache
connection: keep-alive
transfer-encoding: chunked

4F
event: endpoint
data: /message?sessionId=xxxx

[tzolov]

This doesn't make sense and is incorrect as sseEndpoint must be different from the messageEndpoint

Support scenarios like sseEndpoint=/sessions/f3a390a/sse and messageEndpoint=/sessions/f3a390a/sse

[feichao93]

@tzolov My mistake, It should be sseEndpoint=/sessions/f3a390a/sse and messageEndpoint=/sessions/f3a390a/message

[HarryFQG]

This doesn't make sense and is incorrect as sseEndpoint must be different from the messageEndpoint

Support scenarios like sseEndpoint=/sessions/f3a390a/sse and messageEndpoint=/sessions/f3a390a/sse

@tzolov
I met the same problem in customizing sse endpoint in #67.
So I'm wondering if WebMvcSseServerTransport shouldn't support custom sseEndpoint ?

[baiyun8614]

@tzolov 我的错误，应该是sseEndpoint=/sessions/f3a390a/sse和messageEndpoint=/sessions/f3a390a/message

您好，我能添加您一个联系方式吗？想和你沟通一下关于MCP的一些问题，或者说想向您请教一些问题

[tzolov]

Resolved as part of the 55ee156