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feat: Make SSE endpoint configurable in server transports

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This commit updates the WebFluxSseServerTransport, WebMvcSseServerTransport, and HttpServletSseServerTransport classes to accept the SSE endpoint path as a constructor argument.

This change provides more flexibility in configuring the SSE endpoint, allowing it to be customized instead of being hardcoded to "/sse".
It also aligns the Java SDK's behavior with the Python SDK's SseServerTransport, which already supports this customization.

A default SSE endpoint of "/sse" is maintained for backward compatibility.

Also, addressed minor code quality issues identified by SonarLint and reordered modifiers for static final fields to conform with the Java Language Specification.

Signed-off-by: Alexandros Pappas <alexandros.pappas@yiluhub.com>
This commit is contained in:
Alexandros Pappas 2025-01-16 15:28:35 +01:00 • committed by Christian Tzolov
commit c2ece20cc2
6 changed files with 111 additions and 58 deletions
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8
mcp/src/main/java/org/springframework/ai/mcp/client/McpAsyncClient.java
View file

@ -62,7 +62,7 @@ import org.springframework.ai.mcp.util.Utils;
*/
public class McpAsyncClient {
private final static Logger logger = LoggerFactory.getLogger(McpAsyncClient.class);
private static final Logger logger = LoggerFactory.getLogger(McpAsyncClient.class);
private static TypeReference<Void> VOID_TYPE_REFERENCE = new TypeReference<>() {
};
@ -498,7 +498,7 @@ public class McpAsyncClient {
logger.error("Error handling tools list change notification", error);
return Mono.empty();
}).then(); // Convert to Mono<Void>
};
}
// --------------------------
// Resources
@ -619,7 +619,7 @@ public class McpAsyncClient {
logger.error("Error handling resources list change notification", error);
return Mono.empty();
}).then();
};
}
// --------------------------
// Prompts
@ -680,7 +680,7 @@ public class McpAsyncClient {
return Mono.empty();
}).then(); // Convert to Mono<Void>
}; // @formatter:on
};
}
// --------------------------
// Logging

10
mcp/src/main/java/org/springframework/ai/mcp/client/transport/HttpClientSseClientTransport.java
View file

@ -70,16 +70,16 @@ import java.util.function.Function;
*/
public class HttpClientSseClientTransport implements ClientMcpTransport {
private final static Logger logger = LoggerFactory.getLogger(HttpClientSseClientTransport.class);
private static final Logger logger = LoggerFactory.getLogger(HttpClientSseClientTransport.class);
/** SSE event type for JSON-RPC messages */
private final static String MESSAGE_EVENT_TYPE = "message";
private static final String MESSAGE_EVENT_TYPE = "message";
/** SSE event type for endpoint discovery */
private final static String ENDPOINT_EVENT_TYPE = "endpoint";
private static final String ENDPOINT_EVENT_TYPE = "endpoint";
/** Default SSE endpoint path */
private final static String SSE_ENDPOINT = "/sse";
private static final String SSE_ENDPOINT = "/sse";
/** Base URI for the MCP server */
private final String baseUri;
@ -170,7 +170,7 @@ public class HttpClientSseClientTransport implements ClientMcpTransport {
handler.apply(Mono.just(message)).subscribe();
}
else {
logger.error("Received unrecognized SSE event type: " + event.type());
logger.error("Received unrecognized SSE event type: {}", event.type());
}
}
catch (IOException e) {

8
mcp/src/main/java/org/springframework/ai/mcp/server/McpAsyncServer.java
View file

@ -54,7 +54,7 @@ import org.springframework.ai.mcp.util.Utils;
*/
public class McpAsyncServer {
private final static Logger logger = LoggerFactory.getLogger(McpAsyncServer.class);
private static final Logger logger = LoggerFactory.getLogger(McpAsyncServer.class);
/**
* The MCP session implementation that manages bidirectional JSON-RPC communication
@ -279,7 +279,7 @@ public class McpAsyncServer {
return Mono.empty();
}).then();
};
};
}
// ---------------------------------------
// Tool Management
@ -352,9 +352,7 @@ public class McpAsyncServer {
private DefaultMcpSession.RequestHandler toolsListRequestHandler() {
return params -> {
List<Tool> tools = this.tools.stream().map(toolRegistration -> {
return toolRegistration.tool();
}).toList();
List<Tool> tools = this.tools.stream().map(ToolRegistration::tool).toList();
return Mono.just(new McpSchema.ListToolsResult(tools, null));
};

2
mcp/src/main/java/org/springframework/ai/mcp/server/McpServer.java
View file

@ -208,7 +208,7 @@ public interface McpServer {
*/
public static class Builder {
private final static McpSchema.Implementation DEFAULT_SERVER_INFO = new McpSchema.Implementation("mcp-server",
private static final McpSchema.Implementation DEFAULT_SERVER_INFO = new McpSchema.Implementation("mcp-server",
"1.0.0");
private final ServerMcpTransport transport;

56
mcp/src/main/java/org/springframework/ai/mcp/server/transport/HttpServletSseServerTransport.java
View file

@ -63,6 +63,7 @@ import org.springframework.ai.mcp.spec.ServerMcpTransport;
* </ul>
*
* @author Christian Tzolov
* @author Alexandros Pappas
* @see ServerMcpTransport
* @see HttpServlet
*/
@ -73,8 +74,14 @@ public class HttpServletSseServerTransport extends HttpServlet implements Server
/** Logger for this class */
private static final Logger logger = LoggerFactory.getLogger(HttpServletSseServerTransport.class);
/** The endpoint path for SSE connections */
public static final String SSE_ENDPOINT = "/sse";
public static final String UTF_8 = "UTF-8";
public static final String APPLICATION_JSON = "application/json";
public static final String FAILED_TO_SEND_ERROR_RESPONSE = "Failed to send error response: {}";
/** Default endpoint path for SSE connections */
public static final String DEFAULT_SSE_ENDPOINT = "/sse";
/** Event type for regular messages */
public static final String MESSAGE_EVENT_TYPE = "message";
@ -88,6 +95,9 @@ public class HttpServletSseServerTransport extends HttpServlet implements Server
/** The endpoint path for handling client messages */
private final String messageEndpoint;
/** The endpoint path for handling SSE connections */
private final String sseEndpoint;
/** Map of active client sessions, keyed by session ID */
private final Map<String, ClientSession> sessions = new ConcurrentHashMap<>();
@ -98,14 +108,26 @@ public class HttpServletSseServerTransport extends HttpServlet implements Server
private Function<Mono<McpSchema.JSONRPCMessage>, Mono<McpSchema.JSONRPCMessage>> connectHandler;
/**
* Creates a new HttpServletSseServerTransport instance.
* Creates a new HttpServletSseServerTransport instance with a custom SSE endpoint.
* @param objectMapper The JSON object mapper to use for message
* serialization/deserialization
* @param messageEndpoint The endpoint path where clients will send their messages
* @param sseEndpoint The endpoint path where clients will establish SSE connections
*/
public HttpServletSseServerTransport(ObjectMapper objectMapper, String messageEndpoint, String sseEndpoint) {
this.objectMapper = objectMapper;
this.messageEndpoint = messageEndpoint;
this.sseEndpoint = sseEndpoint;
}
/**
* Creates a new HttpServletSseServerTransport instance with the default SSE endpoint.
* @param objectMapper The JSON object mapper to use for message
* serialization/deserialization
* @param messageEndpoint The endpoint path where clients will send their messages
*/
public HttpServletSseServerTransport(ObjectMapper objectMapper, String messageEndpoint) {
this.objectMapper = objectMapper;
this.messageEndpoint = messageEndpoint;
this(objectMapper, messageEndpoint, DEFAULT_SSE_ENDPOINT);
}
/**
@ -124,7 +146,7 @@ public class HttpServletSseServerTransport extends HttpServlet implements Server
throws ServletException, IOException {
String pathInfo = request.getPathInfo();
if (!SSE_ENDPOINT.equals(pathInfo)) {
if (!sseEndpoint.equals(pathInfo)) {
response.sendError(HttpServletResponse.SC_NOT_FOUND);
return;
}
@ -135,7 +157,7 @@ public class HttpServletSseServerTransport extends HttpServlet implements Server
}
response.setContentType("text/event-stream");
response.setCharacterEncoding("UTF-8");
response.setCharacterEncoding(UTF_8);
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Connection", "keep-alive");
response.setHeader("Access-Control-Allow-Origin", "*");
@ -191,8 +213,8 @@ public class HttpServletSseServerTransport extends HttpServlet implements Server
if (connectHandler != null) {
connectHandler.apply(Mono.just(message)).subscribe(responseMessage -> {
try {
response.setContentType("application/json");
response.setCharacterEncoding("UTF-8");
response.setContentType(APPLICATION_JSON);
response.setCharacterEncoding(UTF_8);
String jsonResponse = objectMapper.writeValueAsString(responseMessage);
PrintWriter writer = response.getWriter();
writer.write(jsonResponse);
@ -205,15 +227,15 @@ public class HttpServletSseServerTransport extends HttpServlet implements Server
"Error processing response: " + e.getMessage());
}
catch (IOException ex) {
logger.error("Failed to send error response: {}", ex.getMessage());
logger.error(FAILED_TO_SEND_ERROR_RESPONSE, ex.getMessage());
}
}
}, error -> {
try {
logger.error("Error processing message: {}", error.getMessage());
McpError mcpError = new McpError(error.getMessage());
response.setContentType("application/json");
response.setCharacterEncoding("UTF-8");
response.setContentType(APPLICATION_JSON);
response.setCharacterEncoding(UTF_8);
response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
String jsonError = objectMapper.writeValueAsString(mcpError);
PrintWriter writer = response.getWriter();
@ -221,13 +243,13 @@ public class HttpServletSseServerTransport extends HttpServlet implements Server
writer.flush();
}
catch (IOException e) {
logger.error("Failed to send error response: {}", e.getMessage());
logger.error(FAILED_TO_SEND_ERROR_RESPONSE, e.getMessage());
try {
response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR,
"Error sending error response: " + e.getMessage());
}
catch (IOException ex) {
logger.error("Failed to send error response: {}", ex.getMessage());
logger.error(FAILED_TO_SEND_ERROR_RESPONSE, ex.getMessage());
}
}
});
@ -240,8 +262,8 @@ public class HttpServletSseServerTransport extends HttpServlet implements Server
logger.error("Invalid message format: {}", e.getMessage());
try {
McpError mcpError = new McpError("Invalid message format: " + e.getMessage());
response.setContentType("application/json");
response.setCharacterEncoding("UTF-8");
response.setContentType(APPLICATION_JSON);
response.setCharacterEncoding(UTF_8);
response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
String jsonError = objectMapper.writeValueAsString(mcpError);
PrintWriter writer = response.getWriter();
@ -249,7 +271,7 @@ public class HttpServletSseServerTransport extends HttpServlet implements Server
writer.flush();
}
catch (IOException ex) {
logger.error("Failed to send error response: {}", ex.getMessage());
logger.error(FAILED_TO_SEND_ERROR_RESPONSE, ex.getMessage());
response.sendError(HttpServletResponse.SC_BAD_REQUEST, "Invalid message format");
}
}

2
mcp/src/main/java/org/springframework/ai/mcp/spec/McpSchema.java
View file

@ -140,7 +140,7 @@ public final class McpSchema {
}
private final static TypeReference<HashMap<String, Object>> MAP_TYPE_REF = new TypeReference<>() {
private static final TypeReference<HashMap<String, Object>> MAP_TYPE_REF = new TypeReference<>() {
};
/**