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fix: add backward compatibility for MCP servers returning older protocol versions

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- Add ProtocolVersions interface with version constants
- Change protocolVersion() to protocolVersions() returning List<String>
- Streamable HTTP clients now support both 2024-11-05 and 2025-03-26
- Fixes compatibility with MCP servers that return 2024-11-05 instead of 2025-03-26

Resolves #436
Related to #438

Signed-off-by: Christian Tzolov <christian.tzolov@broadcom.com>
This commit is contained in:
Christian Tzolov 2025-08-04 12:07:31 +01:00 • committed by Christian Tzolov
commit 5e035ea255
6 changed files with 107 additions and 54 deletions
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7
mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebClientStreamableHttpTransport.java
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@ -34,6 +34,7 @@ import io.modelcontextprotocol.spec.McpSchema;
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;
@ -71,7 +72,7 @@ public class WebClientStreamableHttpTransport implements McpClientTransport {
private static final Logger logger = LoggerFactory.getLogger(WebClientStreamableHttpTransport.class);
private static final String MCP_PROTOCOL_VERSION = "2025-03-26";
private static final String MCP_PROTOCOL_VERSION = ProtocolVersions.MCP_2025_03_26;
private static final String DEFAULT_ENDPOINT = "/mcp";
@ -111,8 +112,8 @@ public class WebClientStreamableHttpTransport implements McpClientTransport {
}
@Override
public String protocolVersion() {
return MCP_PROTOCOL_VERSION;
public List<String> protocolVersions() {
return List.of(ProtocolVersions.MCP_2024_11_05, ProtocolVersions.MCP_2025_03_26);
}
/**

8
mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebFluxSseClientTransport.java
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@ -5,6 +5,7 @@
package io.modelcontextprotocol.client.transport;
import java.io.IOException;
import java.util.List;
import java.util.function.BiConsumer;
import java.util.function.Function;
@ -16,6 +17,7 @@ import io.modelcontextprotocol.spec.McpClientTransport;
import io.modelcontextprotocol.spec.McpError;
import io.modelcontextprotocol.spec.McpSchema;
import io.modelcontextprotocol.spec.McpSchema.JSONRPCMessage;
import io.modelcontextprotocol.spec.ProtocolVersions;
import io.modelcontextprotocol.util.Assert;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
@ -65,7 +67,7 @@ public class WebFluxSseClientTransport implements McpClientTransport {
private static final Logger logger = LoggerFactory.getLogger(WebFluxSseClientTransport.class);
private static final String MCP_PROTOCOL_VERSION = "2024-11-05";
private static final String MCP_PROTOCOL_VERSION = ProtocolVersions.MCP_2024_11_05;
/**
* Event type for JSON-RPC messages received through the SSE connection. The server
@ -172,8 +174,8 @@ public class WebFluxSseClientTransport implements McpClientTransport {
}
@Override
public String protocolVersion() {
return MCP_PROTOCOL_VERSION;
public List<String> protocolVersions() {
return List.of(MCP_PROTOCOL_VERSION);
}
/**

6
mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/server/transport/WebFluxSseServerTransportProvider.java
View file

@ -6,6 +6,7 @@ package io.modelcontextprotocol.server.transport;
import java.io.IOException;
import java.time.Duration;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
import com.fasterxml.jackson.core.type.TypeReference;
@ -15,6 +16,7 @@ import io.modelcontextprotocol.spec.McpSchema;
import io.modelcontextprotocol.spec.McpServerSession;
import io.modelcontextprotocol.spec.McpServerTransport;
import io.modelcontextprotocol.spec.McpServerTransportProvider;
import io.modelcontextprotocol.spec.ProtocolVersions;
import io.modelcontextprotocol.util.Assert;
import io.modelcontextprotocol.util.KeepAliveScheduler;
@ -219,8 +221,8 @@ public class WebFluxSseServerTransportProvider implements McpServerTransportProv
}
@Override
public String protocolVersion() {
return "2024-11-05";
public List<String> protocolVersions() {
return List.of(ProtocolVersions.MCP_2024_11_05);
}
@Override

5
mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/server/transport/WebFluxStreamableServerTransportProvider.java
View file

@ -14,6 +14,7 @@ import io.modelcontextprotocol.spec.McpSchema;
import io.modelcontextprotocol.spec.McpStreamableServerSession;
import io.modelcontextprotocol.spec.McpStreamableServerTransport;
import io.modelcontextprotocol.spec.McpStreamableServerTransportProvider;
import io.modelcontextprotocol.spec.ProtocolVersions;
import io.modelcontextprotocol.server.McpTransportContext;
import io.modelcontextprotocol.util.Assert;
import io.modelcontextprotocol.util.KeepAliveScheduler;
@ -96,8 +97,8 @@ public class WebFluxStreamableServerTransportProvider implements McpStreamableSe
}
@Override
public String protocolVersion() {
return "2025-03-26";
public List<String> protocolVersions() {
return List.of(ProtocolVersions.MCP_2024_11_05, ProtocolVersions.MCP_2025_03_26);
}
@Override

6
mcp-spring/mcp-spring-webmvc/src/main/java/io/modelcontextprotocol/server/transport/WebMvcSseServerTransportProvider.java
View file

@ -6,6 +6,7 @@ package io.modelcontextprotocol.server.transport;
import java.io.IOException;
import java.time.Duration;
import java.util.List;
import java.util.UUID;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.locks.ReentrantLock;
@ -16,6 +17,7 @@ import io.modelcontextprotocol.spec.McpError;
import io.modelcontextprotocol.spec.McpSchema;
import io.modelcontextprotocol.spec.McpServerTransport;
import io.modelcontextprotocol.spec.McpServerTransportProvider;
import io.modelcontextprotocol.spec.ProtocolVersions;
import io.modelcontextprotocol.spec.McpServerSession;
import io.modelcontextprotocol.util.Assert;
import io.modelcontextprotocol.util.KeepAliveScheduler;
@ -210,8 +212,8 @@ public class WebMvcSseServerTransportProvider implements McpServerTransportProvi
}
@Override
public String protocolVersion() {
return "2024-11-05";
public List<String> protocolVersions() {
return List.of(ProtocolVersions.MCP_2024_11_05);
}
@Override

5
mcp-spring/mcp-spring-webmvc/src/main/java/io/modelcontextprotocol/server/transport/WebMvcStreamableServerTransportProvider.java
View file

@ -32,6 +32,7 @@ import io.modelcontextprotocol.spec.McpSchema;
import io.modelcontextprotocol.spec.McpStreamableServerSession;
import io.modelcontextprotocol.spec.McpStreamableServerTransport;
import io.modelcontextprotocol.spec.McpStreamableServerTransportProvider;
import io.modelcontextprotocol.spec.ProtocolVersions;
import io.modelcontextprotocol.util.Assert;
import io.modelcontextprotocol.util.KeepAliveScheduler;
import reactor.core.publisher.Flux;
@ -142,8 +143,8 @@ public class WebMvcStreamableServerTransportProvider implements McpStreamableSer
}
@Override
public String protocolVersion() {
return "2025-03-26";
public List<String> protocolVersions() {
return List.of(ProtocolVersions.MCP_2024_11_05, ProtocolVersions.MCP_2025_03_26);
}
@Override