feat(LibCarla/ros2): [1/7] add DDS middleware abstraction layer for multi-vendor support

LibCarla/cmake/fast_dds/CMakeLists.txt

@@ -9,6 +9,8 @@ file(GLOB libcarla_carla_fastdds_headers
   "${libcarla_source_path}/carla/ros2/subscribers/*.h"
   "${libcarla_source_path}/carla/ros2/listeners/*.h"
   "${libcarla_source_path}/carla/ros2/types/*.h"
+  "${libcarla_source_path}/carla/ros2/dds/*.h"
+  "${libcarla_source_path}/carla/ros2/dds/fastdds/*.h"
   )
 install(FILES ${libcarla_carla_fastdds_headers} DESTINATION include/carla/ros2)
 
@@ -30,6 +32,7 @@ file(GLOB libcarla_fastdds_sources
 if (LIBCARLA_BUILD_RELEASE)
   add_library(carla_fastdds STATIC ${libcarla_fastdds_sources})
 
+  target_compile_definitions(carla_fastdds PRIVATE CARLA_ROS2_DDS_FASTDDS)
   target_compile_options(carla_fastdds PRIVATE -fexceptions)
 
   target_include_directories(carla_fastdds SYSTEM PRIVATE
@@ -48,11 +51,15 @@ if (LIBCARLA_BUILD_DEBUG)
 
   add_library(carla_fastdds_debug STATIC ${libcarla_fastdds_sources})
 
+  target_compile_definitions(carla_fastdds_debug PRIVATE CARLA_ROS2_DDS_FASTDDS)
   target_compile_options(carla_fastdds_debug PRIVATE -fexceptions)
 
   target_include_directories(carla_fastdds_debug SYSTEM PRIVATE
       "${BOOST_INCLUDE_PATH}"
       "${RPCLIB_INCLUDE_PATH}")
+
+  target_include_directories(carla_fastdds_debug PRIVATE "${FASTDDS_INCLUDE_PATH}")
+  target_include_directories(carla_fastdds_debug PRIVATE "${libcarla_source_path}/carla/ros2")
   install(TARGETS carla_fastdds_debug DESTINATION lib)
   set_target_properties(carla_fastdds_debug PROPERTIES COMPILE_FLAGS "${CMAKE_CXX_FLAGS_DEBUG}")
   target_compile_definitions(carla_fastdds_debug PUBLIC -DBOOST_ASIO_ENABLE_BUFFER_DEBUGGING)

LibCarla/source/carla/ros2/dds/DDSMiddleware.h

@@ -0,0 +1,56 @@
+// Copyright (c) 2025 Computer Vision Center (CVC) at the Universitat Autonoma de Barcelona (UAB).
+// This work is licensed under the terms of the MIT license.
+// For a copy, see <https://opensource.org/licenses/MIT>.
+
+#pragma once
+
+#include <string>
+
+namespace carla {
+namespace ros2 {
+
+/// Enumeration of available DDS middleware implementations.
+/// Passed to ROS2::Enable() to select the middleware at startup.
+/// Once set, the middleware cannot be changed without restarting.
+enum class DDSMiddleware {
+  FastDDS
+};
+
+/// Convert a DDSMiddleware enum value to a readable string.
+inline const char* DDSMiddlewareToString(DDSMiddleware middleware) {
+  switch (middleware) {
+    case DDSMiddleware::FastDDS:
+      return "FastDDS";
+  }
+  return "Unknown";
+}
+
+/// Result of parsing a middleware name string.
+struct DDSMiddlewareParseResult {
+  bool valid;
+  DDSMiddleware middleware;
+};
+
+/// Parse a middleware name string (lowercase). Returns {true, middleware} on match,
+/// {false, FastDDS} for unrecognized values.
+inline DDSMiddlewareParseResult DDSMiddlewareFromString(const std::string& name) {
+  if (name == "fastdds") {
+    return {true, DDSMiddleware::FastDDS};
+  }
+  return {false, DDSMiddleware::FastDDS};
+}
+
+/// Return a readable list of middleware implementations compiled into this binary.
+inline std::string GetAvailableMiddlewareString() {
+  std::string result;
+#if defined(CARLA_ROS2_DDS_FASTDDS)
+  result += "FastDDS";
+#endif
+  if (result.empty()) {
+    result = "none";
+  }
+  return result;
+}
+
+} // namespace ros2
+} // namespace carla

LibCarla/source/carla/ros2/dds/DDSMiddlewareFactory.h

@@ -0,0 +1,119 @@
+// Copyright (c) 2025 Computer Vision Center (CVC) at the Universitat Autonoma de Barcelona (UAB).
+// This work is licensed under the terms of the MIT license.
+// For a copy, see <https://opensource.org/licenses/MIT>.
+
+#pragma once
+
+#include <memory>
+#include <string>
+
+#include "carla/ros2/dds/DDSMiddleware.h"
+#include "carla/ros2/dds/IDDSPublisherMiddleware.h"
+#include "carla/ros2/dds/IDDSSubscriberMiddleware.h"
+#include "carla/Logging.h"
+
+#if defined(CARLA_ROS2_DDS_FASTDDS)
+#  include "carla/ros2/dds/fastdds/FastDDSPublisherMiddleware.h"
+#  include "carla/ros2/dds/fastdds/FastDDSSubscriberMiddleware.h"
+#endif
+
+namespace carla {
+namespace ros2 {
+
+/// Factory that creates DDS publisher/subscriber middleware based on the active middleware selection.
+/// The middleware is set once at startup via SetMiddleware() before any DDS entities are created.
+/// After the first entity is created, changing the middleware has undefined behavior.
+class DDSMiddlewareFactory {
+ public:
+  /// Select the DDS middleware for all subsequent publisher/subscriber creation.
+  /// Must be called before any publisher or subscriber is initialized.
+  static void SetMiddleware(DDSMiddleware middleware) {
+    GetActiveMiddleware() = middleware;
+  }
+
+  /// @return The currently selected DDS middleware.
+  static DDSMiddleware GetMiddleware() {
+    return GetActiveMiddleware();
+  }
+
+  /// Check whether a specific middleware was compiled into this binary.
+  static bool IsMiddlewareAvailable(DDSMiddleware middleware) {
+    switch (middleware) {
+      case DDSMiddleware::FastDDS:
+#if defined(CARLA_ROS2_DDS_FASTDDS)
+        return true;
+#else
+        return false;
+#endif
+    }
+    return false;
+  }
+
+  /// Result of middleware resolution — whether resolution succeeded and which middleware to use.
+  struct MiddlewareResolution {
+    bool success;
+    DDSMiddleware middleware;
+  };
+
+  /// Resolve the requested middleware strictly — no fallback to other middleware.
+  /// Returns {true, requested} if available, {false, requested} otherwise.
+  static MiddlewareResolution ResolveMiddleware(DDSMiddleware requested) {
+    if (IsMiddlewareAvailable(requested)) {
+      return {true, requested};
+    }
+    return {false, requested};
+  }
+
+  /// Return a readable list of middleware implementations compiled into this binary.
+  /// Delegates to the free function in DDSMiddleware.h.
+  static std::string GetAvailableMiddlewareString() {
+    return carla::ros2::GetAvailableMiddlewareString();
+  }
+
+  /// Create a publisher middleware for traits type T.
+  /// T must provide:
+  ///   T::msg_type  — the message type
+  template<typename T>
+  static std::unique_ptr<IDDSPublisherMiddleware> CreatePublisher() {
+    switch (GetActiveMiddleware()) {
+      case DDSMiddleware::FastDDS:
+#if defined(CARLA_ROS2_DDS_FASTDDS)
+        return std::unique_ptr<IDDSPublisherMiddleware>(
+            new FastDDSPublisherMiddleware<T>());
+#else
+        log_error("DDSMiddlewareFactory: FastDDS not compiled in");
+        return nullptr;
+#endif
+    }
+    return nullptr;
+  }
+
+  /// Create a subscriber middleware for traits type S.
+  /// S must provide:
+  ///   S::msg_type  — the message type
+  template<typename S>
+  static std::unique_ptr<IDDSSubscriberMiddleware> CreateSubscriber() {
+    switch (GetActiveMiddleware()) {
+      case DDSMiddleware::FastDDS:
+#if defined(CARLA_ROS2_DDS_FASTDDS)
+        return std::unique_ptr<IDDSSubscriberMiddleware>(
+            new FastDDSSubscriberMiddleware<S>());
+#else
+        log_error("DDSMiddlewareFactory: FastDDS not compiled in");
+        return nullptr;
+#endif
+    }
+    return nullptr;
+  }
+
+ private:
+  /// Returns reference to the active middleware selection
+  /// (function-local static for C++11 thread safety).
+  static DDSMiddleware& GetActiveMiddleware() {
+    static DDSMiddleware active_middleware = DDSMiddleware::FastDDS;
+    return active_middleware;
+  }
+};
+
+} // namespace ros2
+} // namespace carla

LibCarla/source/carla/ros2/dds/IDDSPublisherMiddleware.h

@@ -0,0 +1,37 @@
+// Copyright (c) 2025 Computer Vision Center (CVC) at the Universitat Autonoma de Barcelona (UAB).
+// This work is licensed under the terms of the MIT license.
+// For a copy, see <https://opensource.org/licenses/MIT>.
+
+#pragma once
+
+#include <string>
+
+namespace carla {
+namespace ros2 {
+
+/// Type-erased abstract interface for a DDS publisher middleware.
+/// Concrete implementations handle all vendor-specific DDS entity creation,
+/// type registration, and data writing.
+class IDDSPublisherMiddleware {
+ public:
+  virtual ~IDDSPublisherMiddleware() = default;
+
+  /// Initialize DDS entities (participant, publisher, topic, writer).
+  /// @param topic_name  Full DDS topic name including "rt/" prefix.
+  /// @return true on success.
+  virtual bool Init(const std::string& topic_name) = 0;
+
+  /// Serialize and write a message to the DDS network.
+  /// @param message_data  Pointer to the message object (type-erased, cast internally).
+  /// @return true if the write succeeded.
+  virtual bool Publish(void* message_data) = 0;
+
+  /// @return true if at least one subscriber is matched.
+  virtual bool IsAlive() const = 0;
+
+  /// @return The DDS topic name this publisher is bound to.
+  virtual std::string GetTopicName() const = 0;
+};
+
+} // namespace ros2
+} // namespace carla

LibCarla/source/carla/ros2/dds/IDDSSubscriberMiddleware.h

@@ -0,0 +1,38 @@
+// Copyright (c) 2025 Computer Vision Center (CVC) at the Universitat Autonoma de Barcelona (UAB).
+// This work is licensed under the terms of the MIT license.
+// For a copy, see <https://opensource.org/licenses/MIT>.
+
+#pragma once
+
+#include <string>
+
+namespace carla {
+namespace ros2 {
+
+/// Type-erased abstract interface for a DDS subscriber middleware.
+/// Concrete implementations write received messages directly into the caller-provided
+/// storage (message_ptr / new_message_flag) to avoid an extra copy.
+class IDDSSubscriberMiddleware {
+ public:
+  virtual ~IDDSSubscriberMiddleware() = default;
+
+  /// Initialize DDS entities (participant, subscriber, topic, reader).
+  /// The middleware writes incoming messages to *message_ptr and sets *new_message_flag = true.
+  /// @param topic_name       Full DDS topic name.
+  /// @param message_ptr      Pointer to the message storage owned by SubscriberImpl<S>.
+  /// @param new_message_flag Pointer to the new-message flag owned by SubscriberImpl<S>.
+  /// @return true on success.
+  virtual bool Init(
+      const std::string& topic_name,
+      void* message_ptr,
+      bool* new_message_flag) = 0;
+
+  /// @return true if at least one publisher is matched.
+  virtual bool IsAlive() const = 0;
+
+  /// @return The DDS topic name this subscriber is bound to.
+  virtual std::string GetTopicName() const = 0;
+};
+
+} // namespace ros2
+} // namespace carla