MCP server w.i.p.

examples/mcp_server/example-mcp-server.cc

@@ -1,5 +1,11 @@
 #include <iostream>
 
+#ifdef _WIN32
+#include <windows.h>
+#else
+#include <unistd.h>
+#endif
+
 #include "prim-types.hh"
 #include "tydra/mcp-server.hh"
 #include "tydra/command-and-history.hh"
@@ -20,24 +26,28 @@ int main(int argc, char **argv) {
 
   }
 
-  std::cout << "is_setr " << parser.is_set("--port") << "\n";
+  int port = 8085;
 
   double portval;
-  if (!parser.get("--port", portval)) {
-    std::cerr << "--port is missing or invalid\n";
-    return -1;
+  if (parser.is_set("--port")) {
+    if (!parser.get("--port", portval)) {
+      std::cerr << "--port is missing or invalid\n";
+      return -1;
+    }
+    port = int(portval);
   }
 
-  int port = int(portval);
   
-  std::string hostname;
-  if (!parser.get("--host", hostname)) {
-    std::cerr << "--host is missing or invalid\n";
-    return -1;
+  std::string hostname = "localhost";
+  if (parser.is_set("--host")) {
+    if (!parser.get("--host", hostname)) {
+      std::cerr << "--host is missing or invalid\n";
+      return -1;
+    }
   }
 
-  std::cout << "port " << port << "\n";
-  std::cout << "hostname " << hostname << "\n";
+
+  std::cout << "http://" + hostname << ":" << port << "/mcp" << "\n";
 
   tydra::MCPServer server;
   if (!server.init(port, hostname)) {
@@ -45,16 +55,27 @@ int main(int argc, char **argv) {
     return -1;
   }
 
+  bool done =false;
+  while (!done) {
 
-  Layer empty;
-  
-  tydra::EditHistory hist;
-  hist.layer = std::move(empty);
+#ifdef _WIN32
+      Sleep(1000);
+#else
+      sleep(1);
+#endif
 
-  tydra::HistoryQueue queue;
-  if (!queue.push(std::move(hist))) {
-    return -1;
+    //Layer empty;
+    //
+    //tydra::EditHistory hist;
+    //hist.layer = std::move(empty);
+
+    //tydra::HistoryQueue queue;
+    //if (!queue.push(std::move(hist))) {
+    //  return -1;
+    //}
   }
+
+  server.stop();
   
   return 0;
 

examples/mcp_server/test-initialize.sh

@@ -0,0 +1,18 @@
+curl -X POST \
+  -H "Content-Type: application/json" \
+  -d '{
+    "jsonrpc": "2.0",
+    "method": "initialize",
+    "params": {
+      "protocolVersion": "2025-03-26",
+      "capabilities": {
+        "tools": {}
+      },
+      "clientInfo": {
+        "name": "curl-client",
+        "version": "1.0.0"
+      }
+    },
+    "id": 1
+  }' \
+  http://localhost:8085/mcp

examples/mcp_server/test-tools-call.sh

@@ -0,0 +1,14 @@
+curl -X POST \
+  -H "Content-Type: application/json" \
+  -d '{
+    "jsonrpc": "2.0",
+    "method": "tools/call",
+    "params": {
+      "name": "tusdcat",
+      "arguments": {
+        "text": "#usda 1.0\n def \"bora\" { }"
+      },
+    },
+    "id": 2
+  }' \
+  http://localhost:8085/mcp

examples/mcp_server/test-tools-list.sh

@@ -0,0 +1,11 @@
+curl -X POST \
+  -H "Content-Type: application/json" \
+  -d '{
+    "jsonrpc": "2.0",
+    "method": "tools/list",
+    "params": {
+      },
+    },
+    "id": 2
+  }' \
+  http://localhost:8085/mcp

src/tydra/mcp-server.cc

@@ -82,7 +82,11 @@ class MCPServer::Impl {
   // Run the server
   bool run();
 
-  bool stop();
+  bool stop() {
+    // Nothing to do here.
+    // mg_stop() is called in dtor.
+    return true;
+  }
   
   // Register a JSON-RPC method handler
   void register_method(const std::string& method, MethodHandler handler);
@@ -91,8 +95,8 @@ class MCPServer::Impl {
   struct mg_context *ctx_ = nullptr; // Pointer to the CivetWeb context
   std::map<std::string, MethodHandler> method_handlers_;
   
-  // Static callback for HTTP requests
-  static int http_handler(struct mg_connection *conn, void *user_data);
+  // Static callback for MCP requests(POST + jsonrpc)
+  static int mcp_handler(struct mg_connection *conn, void *user_data);
   
   // Process JSON-RPC request
   JsonRpcResponse process_request(const JsonRpcRequest& request);
@@ -104,8 +108,7 @@ class MCPServer::Impl {
   JsonRpcResponse create_error_response(int code, const std::string& message, const nlohmann::json& id = nullptr);
 };
 
-// Static HTTP handler implementation
-int MCPServer::Impl::http_handler(struct mg_connection *conn, void *user_data) {
+int MCPServer::Impl::mcp_handler(struct mg_connection *conn, void *user_data) {
   MCPServer::Impl* server = static_cast<MCPServer::Impl*>(user_data);
   
   const struct mg_request_info *request_info = mg_get_request_info(conn);
@@ -157,20 +160,28 @@ int MCPServer::Impl::http_handler(struct mg_connection *conn, void *user_data) {
 JsonRpcRequest MCPServer::Impl::parse_request(const std::string& json_str) {
   JsonRpcRequest request;
   
-    nlohmann::json json_obj = nlohmann::json::parse(json_str);
-    
-    if (json_obj.contains("jsonrpc")) {
-      request.jsonrpc = json_obj["jsonrpc"];
-    }
-    if (json_obj.contains("method")) {
-      request.method = json_obj["method"];
-    }
-    if (json_obj.contains("params")) {
-      request.params = json_obj["params"];
-    }
-    if (json_obj.contains("id")) {
-      request.id = json_obj["id"];
-    }
+  nlohmann::json json_obj;
+  if (!nlohmann::json::accept(json_str)) {
+    // Return invalid request on parse error
+    request.method = "";
+    request.jsonrpc = "";
+    return request;
+  }
+  
+  json_obj = nlohmann::json::parse(json_str);
+  
+  if (json_obj.contains("jsonrpc")) {
+    request.jsonrpc = json_obj["jsonrpc"];
+  }
+  if (json_obj.contains("method")) {
+    request.method = json_obj["method"];
+  }
+  if (json_obj.contains("params")) {
+    request.params = json_obj["params"];
+  }
+  if (json_obj.contains("id")) {
+    request.id = json_obj["id"];
+  }
   
   return request;
 }
@@ -188,13 +199,13 @@ JsonRpcResponse MCPServer::Impl::process_request(const JsonRpcRequest& request)
   }
   
   // Execute method handler
-    nlohmann::json result = handler_it->second(request.params);
-    
-    JsonRpcResponse response;
-    response.id = request.id;
-    response.result = result;
-    
-    return response;
+  nlohmann::json result = handler_it->second(request.params);
+  
+  JsonRpcResponse response;
+  response.id = request.id;
+  response.result = result;
+  
+  return response;
 }
 
 JsonRpcResponse MCPServer::Impl::create_error_response(int code, const std::string& message, const nlohmann::json& id) {
@@ -216,6 +227,36 @@ bool MCPServer::Impl::init(int port, const std::string &host) {
   // TODO
   (void)host;
 
+  // Register MCP initialize method
+  register_method("initialize", [](const nlohmann::json& params) -> nlohmann::json {
+    // Extract client info if provided
+    std::string client_name = "unknown";
+    std::string client_version = "unknown";
+    
+    if (params.contains("clientInfo")) {
+      auto client_info = params["clientInfo"];
+      if (client_info.contains("name")) {
+        client_name = client_info["name"];
+      }
+      if (client_info.contains("version")) {
+        client_version = client_info["version"];
+      }
+    }
+    
+    // Return server capabilities
+    return nlohmann::json{
+      {"protocolVersion", "2025-03-26"},
+      {"serverInfo", {
+        {"name", "tinyusdz-mcp-server"},
+        {"version", "1.0.0"}
+      }},
+      {"capabilities", {
+        {"tools", nlohmann::json::object()},
+        {"resources", nlohmann::json::object()}
+      }}
+    };
+  });
+
   // CivetWeb options
   std::string port_str = std::to_string(port);
   std::vector<const char *> options;
@@ -232,8 +273,8 @@ bool MCPServer::Impl::init(int port, const std::string &host) {
     return false; // Failed to start server
   }
   
-  // Register HTTP handler for JSON-RPC endpoint
-  mg_set_request_handler(ctx_, "/jsonrpc", http_handler, this);
+  // Register HTTP handler for MCP endpoint
+  mg_set_request_handler(ctx_, "/mcp", mcp_handler, this);
   
   return true; // Server initialized successfully
 }
@@ -253,6 +294,14 @@ bool MCPServer::init(int port, const std::string &host) {
   return impl_->init(port, host);
 }
 
+bool MCPServer::run() {
+  return impl_->run();
+}
+
+bool MCPServer::stop() {
+  return impl_->stop();
+}
+
 } // namespace tydra
 } // namespace tinyusdz