feat: Add subscriber plugins using pluginlib

CMakeLists.txt

@@ -46,6 +46,7 @@ add_library(${PROJECT_NAME} SHARED
   src/web_video_server.cpp
   src/multipart_stream.cpp
   src/streamer.cpp
+  src/subscriber.cpp
   src/utils.cpp
 )
 
@@ -61,14 +62,15 @@ target_link_libraries(${PROJECT_NAME}
     async_web_server_cpp::async_web_server_cpp
     pluginlib::pluginlib
     rclcpp::rclcpp
+    ${sensor_msgs_TARGETS}
     rmw::rmw
     Boost::boost
   PRIVATE
     rclcpp_components::component
 )
 
 add_library(${PROJECT_NAME}_streamers SHARED
-  src/streamers/image_transport_streamer.cpp
+  src/streamers/image_streamer.cpp
   src/streamers/libav_streamer.cpp
   src/streamers/h264_streamer.cpp
   src/streamers/jpeg_streamers.cpp
@@ -92,7 +94,6 @@ target_link_libraries(${PROJECT_NAME}_streamers
   ${PROJECT_NAME}
   async_web_server_cpp::async_web_server_cpp
   cv_bridge::cv_bridge
-  image_transport::image_transport
   pluginlib::pluginlib
   rclcpp::rclcpp
   ${sensor_msgs_TARGETS}
@@ -104,6 +105,25 @@ target_link_libraries(${PROJECT_NAME}_streamers
   ${swscale_LIBRARIES}
 )
 
+add_library(${PROJECT_NAME}_subscribers SHARED
+  src/subscribers/image_transport_subscriber.cpp
+)
+
+target_include_directories(${PROJECT_NAME}_subscribers
+  PUBLIC
+    "$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>"
+    "$<INSTALL_INTERFACE:include/${PROJECT_NAME}>"
+)
+
+target_link_libraries(${PROJECT_NAME}_subscribers
+  ${PROJECT_NAME}
+  async_web_server_cpp::async_web_server_cpp
+  image_transport::image_transport
+  pluginlib::pluginlib
+  rclcpp::rclcpp
+  ${sensor_msgs_TARGETS}
+)
+
 ## Declare a cpp executable
 add_executable(${PROJECT_NAME}_node
   src/web_video_server_node.cpp
@@ -115,7 +135,8 @@ target_link_libraries(${PROJECT_NAME}_node
 
 rclcpp_components_register_nodes(${PROJECT_NAME} "web_video_server::WebVideoServer")
 
-pluginlib_export_plugin_description_file(web_video_server plugins.xml)
+pluginlib_export_plugin_description_file(web_video_server streamer_plugins.xml)
+pluginlib_export_plugin_description_file(web_video_server subscriber_plugins.xml)
 
 #############
 ## Install ##
@@ -127,7 +148,7 @@ install(
 )
 
 install(
-  TARGETS ${PROJECT_NAME} ${PROJECT_NAME}_streamers
+  TARGETS ${PROJECT_NAME} ${PROJECT_NAME}_streamers ${PROJECT_NAME}_subscribers
   EXPORT export_${PROJECT_NAME}
   LIBRARY DESTINATION lib
   ARCHIVE DESTINATION lib

README.md

@@ -4,18 +4,22 @@ This node provides HTTP streaming of ROS topics in various formats, making it ea
 
 ## Features
 
+- Subscribe to ROS topics in multiple formats:
+  - image_transport
+
 - Stream ROS image topics over HTTP in multiple formats:
   - MJPEG (Motion JPEG)
   - VP8 (WebM)
   - VP9 (WebM)
   - H264 (MP4)
   - PNG streams
   - ROS compressed image streams
+
 - Query snapshots of image topics in multiple formats:
   - JPEG
   - PNG
   - ROS compressed image
-- Plugin-based architecture for easy addition of new streaming formats
+- Plugin-based architecture for easy addition of new subscribers or streamer formats
 - Adjustable quality, size, and other streaming parameters
 - Web interface to browse available image topics
 - Support for different QoS profiles in ROS 2
@@ -91,6 +95,7 @@ ros2 run web_video_server web_video_server
 | `server_threads` | int | 1 | 1+ | Number of server threads for handling HTTP requests |
 | `ros_threads` | int | 2 | 1+ | Number of threads for ROS message handling |
 | `verbose` | bool | false | true, false | Enable verbose logging |
+| `default_qos_profile` | string | "default" | "default", "system_default", "sensor_data", "services_default" | QoS profile for ROS 2 subscribers |
 | `default_stream_type` | string | "mjpeg" | "mjpeg", "vp8", "vp9", "h264", "png", "ros_compressed" | Default format for video streams |
 | `publish_rate` | double | -1.0 | -1.0 or positive value | Rate for republishing images (-1.0 means no republishing) |
 
@@ -210,6 +215,9 @@ The response is plain text in the form `stopped=<count>`, where `<count>` is the
 ## Creating custom streamer plugins
 See the [custom streamer plugin tutorial](doc/custom-streamer-plugin.md) for information on how to write your own streamer plugins.
 
+## Creating custom subscriber plugins
+See the [custom subscriber plugin tutorial](doc/custom-subscriber-plugin.md) for information on how to write your own subscriber plugins.
+
 ## About
 This project is released as part of the [Robot Web Tools](https://robotwebtools.github.io/) effort.