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HttpClientStreamableHttpTransport: handle HTTP 405

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- Fixes #877

Signed-off-by: Daniel Garnier-Moiroux <git@garnier.wf>
This commit is contained in:
Daniel Garnier-Moiroux 2026-04-02 15:41:07 +02:00 • committed by Daniel Garnier-Moiroux
commit 8e1c5d0cd4
2 changed files with 25 additions and 5 deletions
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8
mcp-core/src/main/java/io/modelcontextprotocol/client/transport/HttpClientStreamableHttpTransport.java
View file

@ -298,6 +298,10 @@ public class HttpClientStreamableHttpTransport implements McpClientTransport {
"Authorization error connecting to SSE stream",
responseEvent.responseInfo()));
}
else if (statusCode == METHOD_NOT_ALLOWED) {
logger.debug("The server does not support SSE streams, using request-response mode.");
return Flux.empty();
}
if (!(responseEvent instanceof ResponseSubscribers.SseResponseEvent sseResponseEvent)) {
return Flux.<McpSchema.JSONRPCMessage>error(new McpTransportException(
@ -344,10 +348,6 @@ public class HttpClientStreamableHttpTransport implements McpClientTransport {
return Flux.empty();
}
}
else if (statusCode == METHOD_NOT_ALLOWED) { // NotAllowed
logger.debug("The server does not support SSE streams, using request-response mode.");
return Flux.empty();
}
else if (statusCode == NOT_FOUND) {
if (transportSession != null && transportSession.sessionId().isPresent()) {

22
mcp-test/src/test/java/io/modelcontextprotocol/client/transport/HttpClientStreamableHttpTransportErrorHandlingTest.java
View file

@ -18,7 +18,6 @@ import java.util.function.Predicate;
import com.sun.net.httpserver.HttpServer;
import io.modelcontextprotocol.client.transport.customizer.McpHttpClientAuthorizationErrorHandler;
import io.modelcontextprotocol.common.McpTransportContext;
import org.reactivestreams.Publisher;
import io.modelcontextprotocol.server.transport.TomcatTestUtil;
import io.modelcontextprotocol.spec.HttpHeaders;
import io.modelcontextprotocol.spec.McpClientTransport;
@ -34,6 +33,7 @@ import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.Timeout;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.ValueSource;
import org.reactivestreams.Publisher;
import reactor.core.publisher.Mono;
import reactor.test.StepVerifier;
@ -369,6 +369,26 @@ public class HttpClientStreamableHttpTransportErrorHandlingTest {
StepVerifier.create(transport.closeGracefully()).verifyComplete();
}
@Test
void test405OnConnectReturnsEmptyFlux() {
serverSseResponseStatus.set(405);
AtomicReference<Throwable> capturedException = new AtomicReference<>();
var transport = HttpClientStreamableHttpTransport.builder(HOST).openConnectionOnStartup(true).build();
transport.setExceptionHandler(capturedException::set);
var messages = new ArrayList<McpSchema.JSONRPCMessage>();
StepVerifier.create(transport.connect(msg -> msg.doOnNext(messages::add))).verifyComplete();
Awaitility.await()
.atMost(Duration.ofSeconds(1))
.untilAsserted(() -> assertThat(processedSseConnectCount.get()).isEqualTo(1));
assertThat(messages).isEmpty();
assertThat(capturedException.get()).isNull();
StepVerifier.create(transport.closeGracefully()).verifyComplete();
}
@Nested
class AuthorizationError {