fix: resolve MCP Gateway SSE hanging issue by replacing RouterFunction with SseEmitter in RestController

axhub-gateway/src/main/java/io/shinhanlife/axhub/biz/mcp/gateway/sync/CustomWebMvcSseServerTransportProvider.java

@@ -0,0 +1,146 @@
+package io.shinhanlife.axhub.biz.mcp.gateway.sync;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import io.modelcontextprotocol.json.TypeRef;
+import io.modelcontextprotocol.spec.McpSchema;
+import io.modelcontextprotocol.spec.McpServerSession;
+import io.modelcontextprotocol.spec.McpServerTransport;
+import io.modelcontextprotocol.spec.McpServerTransportProvider;
+import org.springframework.http.MediaType;
+import org.springframework.web.servlet.function.RouterFunction;
+import org.springframework.web.servlet.function.RouterFunctions;
+import org.springframework.web.servlet.function.ServerResponse;
+import reactor.core.publisher.Mono;
+
+import java.util.Map;
+import java.util.UUID;
+import java.util.concurrent.ConcurrentHashMap;
+
+import static org.springframework.web.servlet.function.RequestPredicates.GET;
+import static org.springframework.web.servlet.function.RequestPredicates.POST;
+import static org.springframework.web.servlet.function.RequestPredicates.accept;
+
+public class CustomWebMvcSseServerTransportProvider implements McpServerTransportProvider {
+
+    private McpServerSession.Factory sessionFactory;
+    private final String sseEndpoint;
+    private final String messageEndpoint;
+    private final Map<String, McpServerSession> sessions = new ConcurrentHashMap<>();
+    private final ObjectMapper objectMapper;
+
+    public CustomWebMvcSseServerTransportProvider(String sseEndpoint, String messageEndpoint, ObjectMapper objectMapper) {
+        this.sseEndpoint = sseEndpoint;
+        this.messageEndpoint = messageEndpoint;
+        this.objectMapper = objectMapper != null ? objectMapper : new ObjectMapper();
+    }
+
+    @Override
+    public void setSessionFactory(McpServerSession.Factory sessionFactory) {
+        this.sessionFactory = sessionFactory;
+    }
+
+    @Override
+    public Mono<Void> closeGracefully() {
+        return Mono.fromRunnable(() -> {
+            sessions.values().forEach(session -> {
+                try {
+                    session.closeGracefully().subscribe();
+                } catch (Exception ignored) {}
+            });
+            sessions.clear();
+        });
+    }
+
+    @Override
+    public Mono<Void> notifyClients(String method, Object params) {
+        return Mono.when(sessions.values().stream()
+                .map(session -> session.sendNotification(method, params))
+                .toList());
+    }
+
+    public org.springframework.web.servlet.mvc.method.annotation.SseEmitter handleSse() {
+        if (sessionFactory == null) {
+            throw new IllegalStateException("SessionFactory not configured");
+        }
+        
+        org.springframework.web.servlet.mvc.method.annotation.SseEmitter emitter = new org.springframework.web.servlet.mvc.method.annotation.SseEmitter(-1L);
+        String sessionId = UUID.randomUUID().toString();
+        
+        CustomMcpSessionTransport sessionTransport = new CustomMcpSessionTransport(emitter, sessionId);
+        McpServerSession session = sessionFactory.create(sessionTransport);
+        sessions.put(sessionId, session);
+        
+        emitter.onCompletion(() -> sessions.remove(sessionId));
+        emitter.onTimeout(() -> sessions.remove(sessionId));
+        
+        new Thread(() -> {
+            try {
+                Thread.sleep(100);
+                emitter.send(org.springframework.web.servlet.mvc.method.annotation.SseEmitter.event().name("endpoint").data(messageEndpoint + "?sessionId=" + sessionId));
+            } catch (Exception e) {
+                emitter.completeWithError(e);
+            }
+        }).start();
+        
+        return emitter;
+    }
+
+    public org.springframework.http.ResponseEntity<String> handleMessage(String sessionId, String body) {
+        if (sessionId == null || !sessions.containsKey(sessionId)) {
+            return org.springframework.http.ResponseEntity.badRequest().body("Missing or invalid sessionId");
+        }
+        
+        McpServerSession session = sessions.get(sessionId);
+        try {
+            java.util.Map<String, Object> map = objectMapper.readValue(body, new com.fasterxml.jackson.core.type.TypeReference<java.util.Map<String, Object>>() {});
+            io.modelcontextprotocol.spec.McpSchema.JSONRPCMessage message;
+            
+            if (map.containsKey("id")) {
+                if (map.containsKey("method")) {
+                    message = objectMapper.convertValue(map, io.modelcontextprotocol.spec.McpSchema.JSONRPCRequest.class);
+                } else {
+                    message = objectMapper.convertValue(map, io.modelcontextprotocol.spec.McpSchema.JSONRPCResponse.class);
+                }
+            } else {
+                message = objectMapper.convertValue(map, io.modelcontextprotocol.spec.McpSchema.JSONRPCNotification.class);
+            }
+            
+            session.handle(message).subscribe();
+            return org.springframework.http.ResponseEntity.ok().build();
+        } catch (Exception e) {
+            return org.springframework.http.ResponseEntity.status(500).body(e.getMessage());
+        }
+    }
+
+    private class CustomMcpSessionTransport implements McpServerTransport {
+        private final org.springframework.web.servlet.mvc.method.annotation.SseEmitter emitter;
+        private final String sessionId;
+
+        public CustomMcpSessionTransport(org.springframework.web.servlet.mvc.method.annotation.SseEmitter emitter, String sessionId) {
+            this.emitter = emitter;
+            this.sessionId = sessionId;
+        }
+
+        @Override
+        public Mono<Void> sendMessage(McpSchema.JSONRPCMessage message) {
+            return Mono.fromRunnable(() -> {
+                try {
+                    String json = objectMapper.writeValueAsString(message);
+                    emitter.send(org.springframework.web.servlet.mvc.method.annotation.SseEmitter.event().name("message").data(json));
+                } catch (Exception e) {
+                    throw new RuntimeException(e);
+                }
+            });
+        }
+
+        @Override
+        public Mono<Void> closeGracefully() {
+            return Mono.fromRunnable(emitter::complete);
+        }
+
+        @Override
+        public <T> T unmarshalFrom(Object object, TypeRef<T> typeRef) {
+            return objectMapper.convertValue(object, objectMapper.constructType(typeRef.getType()));
+        }
+    }
+}

axhub-gateway/src/main/java/io/shinhanlife/axhub/biz/mcp/gateway/sync/DynamicMcpController.java

@@ -0,0 +1,42 @@
+package io.shinhanlife.axhub.biz.mcp.gateway.sync;
+
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+import org.springframework.web.servlet.mvc.method.annotation.SseEmitter;
+
+@RestController
+public class DynamicMcpController {
+
+    private final DynamicMcpServerManager manager;
+
+    public DynamicMcpController(DynamicMcpServerManager manager) {
+        this.manager = manager;
+    }
+
+    @GetMapping("/mcp/sse/{category}")
+    public SseEmitter handleSse(@PathVariable("category") String category) {
+        CustomWebMvcSseServerTransportProvider transport = manager.getTransport(category);
+        if (transport == null) {
+            throw new IllegalArgumentException("Unknown category: " + category);
+        }
+        return transport.handleSse();
+    }
+
+    @PostMapping("/mcp/message/{category}")
+    public ResponseEntity<String> handleMessage(
+            @PathVariable("category") String category,
+            @RequestParam("sessionId") String sessionId,
+            @RequestBody String body) {
+            
+        CustomWebMvcSseServerTransportProvider transport = manager.getTransport(category);
+        if (transport == null) {
+            return ResponseEntity.badRequest().body("Unknown category: " + category);
+        }
+        return transport.handleMessage(sessionId, body);
+    }
+}

axhub-gateway/src/main/java/io/shinhanlife/axhub/biz/mcp/gateway/sync/DynamicMcpRouterConfig.java

@@ -1,29 +0,0 @@
-package io.shinhanlife.axhub.biz.mcp.gateway.sync;
-
-import org.springframework.context.annotation.Bean;
-import org.springframework.context.annotation.Configuration;
-import org.springframework.web.servlet.function.RouterFunction;
-import org.springframework.web.servlet.function.ServerResponse;
-
-/**
- * @package io.shinhanlife.axhub.biz.mcp.gateway.sync
- * @className DynamicMcpRouterConfig
- * @description AX HUB 시스템 처리 클래스
- * @author 김형식
- * @create 2026.09.01
- * <pre>
- * ---------- 개정이력 ----------
- * 수정일      수정자    수정내용
- * ---------- -------- ---------------------------
- * 2026.09.01  김형식    최초생성
- * 
- * </pre>
- */
-@Configuration
-public class DynamicMcpRouterConfig {
-
-    @Bean
-    public RouterFunction<ServerResponse> dynamicMcpRouterFunction(DynamicMcpServerManager manager) {
-        return manager.getDynamicRouter();
-    }
-}

axhub-gateway/src/main/java/io/shinhanlife/axhub/biz/mcp/gateway/sync/DynamicMcpServerManager.java

@@ -5,49 +5,32 @@ import io.modelcontextprotocol.server.McpSyncServer;
 import io.shinhanlife.axhub.biz.mcp.gateway.dto.ToolMetadata;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
-import org.springframework.ai.mcp.server.webmvc.transport.WebMvcSseServerTransportProvider;
 import org.springframework.stereotype.Component;
-import org.springframework.web.servlet.function.HandlerFunction;
+import com.fasterxml.jackson.databind.ObjectMapper;
-import org.springframework.web.servlet.function.RouterFunction;
-import org.springframework.web.servlet.function.ServerResponse;
 
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
-import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.stream.Collectors;
 
-/**
- * @package io.shinhanlife.axhub.biz.mcp.gateway.sync
- * @className DynamicMcpServerManager
- * @description AX HUB 시스템 처리 클래스
- * @author 김형식
- * @create 2026.09.01
- * <pre>
- * ---------- 개정이력 ----------
- * 수정일      수정자    수정내용
- * ---------- -------- ---------------------------
- * 2026.09.01  김형식    최초생성
- * 
- * </pre>
- */
 @Component
 public class DynamicMcpServerManager {
     private static final Logger log = LoggerFactory.getLogger(DynamicMcpServerManager.class);
 
     private final Map<String, McpSyncServer> categoryServers = new ConcurrentHashMap<>();
-    private final Map<String, WebMvcSseServerTransportProvider> categoryTransports = new ConcurrentHashMap<>();
+    private final Map<String, CustomWebMvcSseServerTransportProvider> categoryTransports = new ConcurrentHashMap<>();
     private final Map<String, Set<String>> managedToolNamesPerCategory = new ConcurrentHashMap<>();
 
     private final RegistryMcpToolSpecificationFactory specificationFactory;
+    private final ObjectMapper objectMapper;
 
-    public DynamicMcpServerManager(RegistryMcpToolSpecificationFactory specificationFactory) {
+    public DynamicMcpServerManager(RegistryMcpToolSpecificationFactory specificationFactory, ObjectMapper objectMapper) {
         this.specificationFactory = specificationFactory;
+        this.objectMapper = objectMapper;
 
         // Pre-initialize basic categories so their endpoints are always open
-        // even if there are 0 tools registered in Redis initially.
         getOrCreateServer("common");
         getOrCreateServer("hr");
         getOrCreateServer("payment");
@@ -64,13 +47,11 @@ public class DynamicMcpServerManager {
             String ssePath = "/mcp/sse/" + key;
             String msgPath = "/mcp/message/" + key;
 
-            WebMvcSseServerTransportProvider transport = WebMvcSseServerTransportProvider.builder()
+            CustomWebMvcSseServerTransportProvider transport = new CustomWebMvcSseServerTransportProvider(ssePath, msgPath, objectMapper);
-                .sseEndpoint(ssePath)
-                .messageEndpoint(msgPath)
-                .build();
 
             McpSyncServer newServer = McpServer.sync(transport)
                 .serverInfo("AXHUB-Gateway-" + key, "1.0.0")
+                .capabilities(io.modelcontextprotocol.spec.McpSchema.ServerCapabilities.builder().tools(true).build())
                 .build();
                 
             categoryTransports.put(key, transport);
@@ -114,19 +95,8 @@ public class DynamicMcpServerManager {
         return Collections.unmodifiableSet(categoryServers.keySet());
     }
 
-    public RouterFunction<ServerResponse> getDynamicRouter() {
+    public CustomWebMvcSseServerTransportProvider getTransport(String categoryKey) {
-        return request -> {
+        String safeCategory = (categoryKey == null || categoryKey.trim().isEmpty()) ? "common" : categoryKey.toLowerCase();
-            log.info("[DynamicMcpRouter] Incoming request path: {}, method: {}", request.path(), request.method());
+        return categoryTransports.get(safeCategory);
-            for (Map.Entry<String, WebMvcSseServerTransportProvider> entry : categoryTransports.entrySet()) {
-                WebMvcSseServerTransportProvider transport = entry.getValue();
-                Optional<HandlerFunction<ServerResponse>> handler = transport.getRouterFunction().route(request);
-                if (handler.isPresent()) {
-                    log.info("[DynamicMcpRouter] Matched handler for key: {}", entry.getKey());
-                    return handler;
-                }
-            }
-            log.info("[DynamicMcpRouter] No handler matched for path: {}", request.path());
-            return Optional.empty();
-        };
     }
 }