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[fix] when mcp server not give mcp session id ,mcp session store null… #554

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[fix] when mcp server not give mcp session id ,mcp session store null… #554

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772c795
[fix] when mcp server not give mcp session id ,mcp session store null…
Sep 16, 2025
eb31fed
[fix] when mcp server not give mcp session id ,
Sep 17, 2025
8e97e26
[fix] when mcp server not give mcp session id ,
Sep 17, 2025
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41 changes: 15 additions & 26 deletions .../main/java/io/modelcontextprotocol/client/transport/WebClientStreamableHttpTransport.java
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Original file line number Diff line number Diff line change
Expand Up @@ -4,46 +4,35 @@

package io.modelcontextprotocol.client.transport;

import java.io.IOException;
import java.util.List;
import java.util.Optional;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Consumer;
import java.util.function.Function;

import io.modelcontextprotocol.json.McpJsonMapper;
import io.modelcontextprotocol.json.TypeRef;
import io.modelcontextprotocol.spec.*;
import io.modelcontextprotocol.util.Assert;
import io.modelcontextprotocol.util.Utils;
import org.reactivestreams.Publisher;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.ParameterizedTypeReference;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.codec.ServerSentEvent;
import org.springframework.util.StringUtils;
import org.springframework.web.reactive.function.client.ClientResponse;
import org.springframework.web.reactive.function.client.WebClient;
import org.springframework.web.reactive.function.client.WebClientResponseException;

import io.modelcontextprotocol.json.TypeRef;
import io.modelcontextprotocol.json.McpJsonMapper;

import io.modelcontextprotocol.spec.DefaultMcpTransportSession;
import io.modelcontextprotocol.spec.DefaultMcpTransportStream;
import io.modelcontextprotocol.spec.HttpHeaders;
import io.modelcontextprotocol.spec.McpClientTransport;
import io.modelcontextprotocol.spec.McpError;
import io.modelcontextprotocol.spec.McpSchema;
import io.modelcontextprotocol.spec.McpTransportException;
import io.modelcontextprotocol.spec.McpTransportSession;
import io.modelcontextprotocol.spec.McpTransportSessionNotFoundException;
import io.modelcontextprotocol.spec.McpTransportStream;
import io.modelcontextprotocol.spec.ProtocolVersions;
import io.modelcontextprotocol.util.Assert;
import io.modelcontextprotocol.util.Utils;
import reactor.core.Disposable;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;
import reactor.util.function.Tuple2;
import reactor.util.function.Tuples;

import java.io.IOException;
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You should revert unrelated parts, keep null check changes only.

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@caojiaqi123 caojiaqi123 Sep 17, 2025 •
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ok, reverted unrelated parts. Submit MR first time, thx reminder. @quaff

import java.util.List;
import java.util.Optional;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Consumer;
import java.util.function.Function;

/**
* An implementation of the Streamable HTTP protocol as defined by the
* <code>2025-03-26</code> version of the MCP specification.
Expand Down Expand Up @@ -279,8 +268,8 @@ public Mono<Void> sendMessage(McpSchema.JSONRPCMessage message) {
})
.bodyValue(message)
.exchangeToFlux(response -> {
if (transportSession
.markInitialized(response.headers().asHttpHeaders().getFirst(HttpHeaders.MCP_SESSION_ID))) {
String mcpSessionId = response.headers().asHttpHeaders().getFirst(HttpHeaders.MCP_SESSION_ID);
if (StringUtils.hasText(mcpSessionId) && transportSession.markInitialized(mcpSessionId)) {
// Once we have a session, we try to open an async stream for
// the server to send notifications and requests out-of-band.
reconnect(null).contextWrite(sink.contextView()).subscribe();
Expand Down
61 changes: 28 additions & 33 deletions ...main/java/io/modelcontextprotocol/client/transport/HttpClientStreamableHttpTransport.java
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,25 @@

package io.modelcontextprotocol.client.transport;

import io.modelcontextprotocol.client.transport.ResponseSubscribers.ResponseEvent;
import io.modelcontextprotocol.client.transport.customizer.McpAsyncHttpClientRequestCustomizer;
import io.modelcontextprotocol.client.transport.customizer.McpSyncHttpClientRequestCustomizer;
import io.modelcontextprotocol.common.McpTransportContext;
import io.modelcontextprotocol.json.McpJsonMapper;
import io.modelcontextprotocol.json.TypeRef;
import io.modelcontextprotocol.spec.*;
import io.modelcontextprotocol.util.Assert;
import io.modelcontextprotocol.util.Utils;
import org.reactivestreams.Publisher;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import reactor.core.Disposable;
import reactor.core.publisher.Flux;
import reactor.core.publisher.FluxSink;
import reactor.core.publisher.Mono;
import reactor.util.function.Tuple2;
import reactor.util.function.Tuples;

import java.io.IOException;
import java.net.URI;
import java.net.http.HttpClient;
Expand All @@ -12,42 +31,13 @@
import java.net.http.HttpResponse.BodyHandler;
import java.time.Duration;
import java.util.List;
import java.util.Objects;
import java.util.Optional;
import java.util.concurrent.CompletionException;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Consumer;
import java.util.function.Function;

import org.reactivestreams.Publisher;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import io.modelcontextprotocol.json.TypeRef;
import io.modelcontextprotocol.json.McpJsonMapper;

import io.modelcontextprotocol.client.transport.customizer.McpAsyncHttpClientRequestCustomizer;
import io.modelcontextprotocol.client.transport.customizer.McpSyncHttpClientRequestCustomizer;
import io.modelcontextprotocol.client.transport.ResponseSubscribers.ResponseEvent;
import io.modelcontextprotocol.common.McpTransportContext;
import io.modelcontextprotocol.spec.DefaultMcpTransportSession;
import io.modelcontextprotocol.spec.DefaultMcpTransportStream;
import io.modelcontextprotocol.spec.HttpHeaders;
import io.modelcontextprotocol.spec.McpClientTransport;
import io.modelcontextprotocol.spec.McpSchema;
import io.modelcontextprotocol.spec.McpTransportException;
import io.modelcontextprotocol.spec.McpTransportSession;
import io.modelcontextprotocol.spec.McpTransportSessionNotFoundException;
import io.modelcontextprotocol.spec.McpTransportStream;
import io.modelcontextprotocol.spec.ProtocolVersions;
import io.modelcontextprotocol.util.Assert;
import io.modelcontextprotocol.util.Utils;
import reactor.core.Disposable;
import reactor.core.publisher.Flux;
import reactor.core.publisher.FluxSink;
import reactor.core.publisher.Mono;
import reactor.util.function.Tuple2;
import reactor.util.function.Tuples;

/**
* An implementation of the Streamable HTTP protocol as defined by the
* <code>2025-03-26</code> version of the MCP specification.
Expand Down Expand Up @@ -87,7 +77,9 @@ public class HttpClientStreamableHttpTransport implements McpClientTransport {
*/
private final HttpClient httpClient;

/** HTTP request builder for building requests to send messages to the server */
/**
* HTTP request builder for building requests to send messages to the server
*/
private final HttpRequest.Builder requestBuilder;

/**
Expand Down Expand Up @@ -442,8 +434,11 @@ public Mono<Void> sendMessage(McpSchema.JSONRPCMessage sentMessage) {
})).onErrorMap(CompletionException.class, t -> t.getCause()).onErrorComplete().subscribe();

})).flatMap(responseEvent -> {
if (transportSession.markInitialized(
responseEvent.responseInfo().headers().firstValue("mcp-session-id").orElseGet(() -> null))) {
String mcpSessionId = responseEvent.responseInfo()
.headers()
.firstValue("mcp-session-id")
.orElseGet(() -> null);
if (Objects.nonNull(mcpSessionId) && transportSession.markInitialized(mcpSessionId)) {
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API Note:
This method exists to be used as a java.util.function.Predicate, filter(Objects::nonNull)

I think mcpSessionId != null should be used here.

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Oh, I see. It is used to listen for notifications. thx!

// Once we have a session, we try to open an async stream for
// the server to send notifications and requests out-of-band.

Expand Down