Add JSON endpoint

Author: jdavidberger

include/web_video_server/web_video_server.h

@@ -49,6 +49,9 @@ class WebVideoServer
   bool handle_list_streams(const async_web_server_cpp::HttpRequest &request,
                            async_web_server_cpp::HttpConnectionPtr connection, const char* begin, const char* end);
 
+  bool handle_list_streams_json(const async_web_server_cpp::HttpRequest &request,
+                           async_web_server_cpp::HttpConnectionPtr connection, const char* begin, const char* end);
+
 private:
   void restreamFrames(double max_age);
   void cleanup_inactive_streams();

src/web_video_server.cpp

@@ -74,6 +74,7 @@ WebVideoServer::WebVideoServer(ros::NodeHandle &nh, ros::NodeHandle &private_nh)
   stream_types_["vp9"] = boost::shared_ptr<ImageStreamerType>(new Vp9StreamerType());
 
   handler_group_.addHandlerForPath("/", boost::bind(&WebVideoServer::handle_list_streams, this, _1, _2, _3, _4));
+  handler_group_.addHandlerForPath("/json", boost::bind(&WebVideoServer::handle_list_streams_json, this, _1, _2, _3, _4));
   handler_group_.addHandlerForPath("/stream", boost::bind(&WebVideoServer::handle_stream, this, _1, _2, _3, _4));
   handler_group_.addHandlerForPath("/stream_viewer",
                                    boost::bind(&WebVideoServer::handle_stream_viewer, this, _1, _2, _3, _4));
@@ -342,8 +343,72 @@ bool WebVideoServer::handle_list_streams(const async_web_server_cpp::HttpRequest
   return true;
 }
 
-}
+bool WebVideoServer::handle_list_streams_json(const async_web_server_cpp::HttpRequest &request,
+                                         async_web_server_cpp::HttpConnectionPtr connection, const char* begin,
+                                         const char* end)
+{
+  std::string image_message_type = ros::message_traits::datatype<sensor_msgs::Image>();
+  std::string camera_info_message_type = ros::message_traits::datatype<sensor_msgs::CameraInfo>();
+
+  ros::master::V_TopicInfo topics;
+  ros::master::getTopics(topics);
+  ros::master::V_TopicInfo::iterator it;
+  std::vector<std::string> image_topics;
+  std::vector<std::string> camera_info_topics;
+  for (it = topics.begin(); it != topics.end(); ++it)
+  {
+    const ros::master::TopicInfo &topic = *it;
+    if (topic.datatype == image_message_type)
+    {
+      image_topics.push_back(topic.name);
+    }
+    else if (topic.datatype == camera_info_message_type)
+    {
+      camera_info_topics.push_back(topic.name);
+    }
+  }
 
+  async_web_server_cpp::HttpReply::builder(async_web_server_cpp::HttpReply::ok).header("Connection", "close").header(
+      "Server", "web_video_server").header("Cache-Control", 
+                                           "no-cache, no-store, must-revalidate, pre-check=0, post-check=0, max-age=0").
+    header("Pragma", "no-cache").
+    header("Content-type", "application/json;").
+    header("Access-Control-Allow-Headers", "*").
+    header("Keep-Alive", "timeout=1").
+    header("Access-Control-Allow-Origin", "*").write(connection);
+
+  connection->write("[");
+  bool first = true;
+  BOOST_FOREACH(std::string & camera_info_topic, camera_info_topics)    
+  {
+    if (boost::algorithm::ends_with(camera_info_topic, "/camera_info"))
+    {
+      std::string base_topic = camera_info_topic.substr(0, camera_info_topic.size() - strlen("camera_info"));
+      std::vector<std::string>::iterator image_topic_itr = image_topics.begin();
+      for (; image_topic_itr != image_topics.end();)
+      {
+        if (boost::starts_with(*image_topic_itr, base_topic))
+        {
+	  if(!first)
+	    connection->write(",");
+	  first = false;
+          connection->write("\"");
+          connection->write(*image_topic_itr);
+          connection->write("\"");
+
+          image_topic_itr = image_topics.erase(image_topic_itr);
+        }
+        else
+        {
+          ++image_topic_itr;
+        }
+      }
+    }
+  }
+  connection->write("]");
+  return true;
+}
+}
 int main(int argc, char **argv)
 {
   ros::init(argc, argv, "web_video_server");