Public Types
typedef websocketpp::connection_hdl	connection_hdl

typedef websocketpp::server< websocketpp::config::asio >	server

Public Member Functions
	telemetry_server ()

void	run (std::string docroot, uint16_t port)

void	set_timer ()

void	on_timer (websocketpp::lib::error_code const &ec)

void	on_http (connection_hdl hdl)

void	on_open (connection_hdl hdl)

void	on_close (connection_hdl hdl)

Detailed Description

The telemetry server accepts connections and sends a message every second to each client containing an integer count. This example can be used as the basis for programs that expose a stream of telemetry data for logging, dashboards, etc.

This example uses the timer based concurrency method and is self contained and singled threaded. Refer to telemetry client for an example of a similar telemetry setup using threads rather than timers.

This example also includes an example simple HTTP server that serves a web dashboard displaying the count. This simple design is suitable for use delivering a small number of files to a small number of clients. It is ideal for cases like embedded dashboards that don't want the complexity of an extra HTTP server to serve static files.

This design will fall over under high traffic or DoS conditions. In such cases you are much better off proxying to a real HTTP server for the http requests.

Definition at line 31 of file telemetry_server.cpp.

Member Typedef Documentation

◆ connection_hdl

websocketpp::connection_hdl telemetry_server::connection_hdl

Definition at line 33 of file telemetry_server.cpp.

◆ server

websocketpp::server<websocketpp::config::asio> telemetry_server::server

Definition at line 34 of file telemetry_server.cpp.

Constructor & Destructor Documentation

◆ telemetry_server()

telemetry_server::telemetry_server ( )

inline

Definition at line 36 of file telemetry_server.cpp.

                       : m_count(0) {
        // set up access channels to only log interesting things
        m_endpoint.clear_access_channels(websocketpp::log::alevel::all);
        m_endpoint.set_access_channels(websocketpp::log::alevel::access_core);
        m_endpoint.set_access_channels(websocketpp::log::alevel::app);
 
        // Initialize the Asio transport policy
        m_endpoint.init_asio();
 
        // Bind the handlers we are using
        using websocketpp::lib::placeholders::_1;
        using websocketpp::lib::bind;
        m_endpoint.set_open_handler(bind(&telemetry_server::on_open,this,_1));
        m_endpoint.set_close_handler(bind(&telemetry_server::on_close,this,_1));
        m_endpoint.set_http_handler(bind(&telemetry_server::on_http,this,_1));
    }

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Member Function Documentation

◆ on_close()

void telemetry_server::on_close ( connection_hdl hdl )

inline

Definition at line 160 of file telemetry_server.cpp.

                                      {
        m_connections.erase(hdl);
    }

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◆ on_http()

void telemetry_server::on_http ( connection_hdl hdl )

inline

Definition at line 109 of file telemetry_server.cpp.

                                     {
        // Upgrade our connection handle to a full connection_ptr
        server::connection_ptr con = m_endpoint.get_con_from_hdl(hdl);
    
        std::ifstream file;
        std::string filename = con->get_resource();
        std::string response;
    
        m_endpoint.get_alog().write(websocketpp::log::alevel::app,
            "http request1: "+filename);
    
        if (filename == "/") {
            filename = m_docroot+"index.html";
        } else {
            filename = m_docroot+filename.substr(1);
        }
        
        m_endpoint.get_alog().write(websocketpp::log::alevel::app,
            "http request2: "+filename);
    
        file.open(filename.c_str(), std::ios::in);
        if (!file) {
            // 404 error
            std::stringstream ss;
        
            ss << "<!doctype html><html><head>"
               << "<title>Error 404 (Resource not found)</title><body>"
               << "<h1>Error 404</h1>"
               << "<p>The requested URL " << filename << " was not found on this server.</p>"
               << "</body></head></html>";
        
            con->set_body(ss.str());
            con->set_status(websocketpp::http::status_code::not_found);
            return;
        }
    
        file.seekg(0, std::ios::end);
        response.reserve(file.tellg());
        file.seekg(0, std::ios::beg);
    
        response.assign((std::istreambuf_iterator<char>(file)),
                        std::istreambuf_iterator<char>());
    
        con->set_body(response);
        con->set_status(websocketpp::http::status_code::ok);
    }

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◆ on_open()

void telemetry_server::on_open ( connection_hdl hdl )

inline

Definition at line 156 of file telemetry_server.cpp.

                                     {
        m_connections.insert(hdl);
    }

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◆ on_timer()

void telemetry_server::on_timer ( websocketpp::lib::error_code const & ec )

inline

Definition at line 88 of file telemetry_server.cpp.

                                                       {
        if (ec) {
            // there was an error, stop telemetry
            m_endpoint.get_alog().write(websocketpp::log::alevel::app,
                    "Timer Error: "+ec.message());
            return;
        }
        
        std::stringstream val;
        val << "count is " << m_count++;
        
        // Broadcast count to all connections
        con_list::iterator it;
        for (it = m_connections.begin(); it != m_connections.end(); ++it) {
            m_endpoint.send(*it,val.str(),websocketpp::frame::opcode::text);
        }
        
        // set timer for next telemetry check
        set_timer();
    }

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◆ run()

void telemetry_server::run	(	std::string	docroot,
		uint16_t	port )

inline

Definition at line 53 of file telemetry_server.cpp.

                                               {
        std::stringstream ss;
        ss << "Running telemetry server on port "<< port <<" using docroot=" << docroot;
        m_endpoint.get_alog().write(websocketpp::log::alevel::app,ss.str());
        
        m_docroot = docroot;
        
        // listen on specified port
        m_endpoint.listen(port);
 
        // Start the server accept loop
        m_endpoint.start_accept();
 
        // Set the initial timer to start telemetry
        set_timer();
 
        // Start the ASIO io_service run loop
        try {
            m_endpoint.run();
        } catch (websocketpp::exception const & e) {
            std::cout << e.what() << std::endl;
        }
    }

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◆ set_timer()

void telemetry_server::set_timer ( )

inline

Definition at line 77 of file telemetry_server.cpp.

                     {
        m_timer = m_endpoint.set_timer(
            1000,
            websocketpp::lib::bind(
                &telemetry_server::on_timer,
                this,
                websocketpp::lib::placeholders::_1
            )
        );
    }

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The documentation for this class was generated from the following file:

libraries/fc/vendor/websocketpp/examples/telemetry_server/telemetry_server.cpp

Public Types

Public Member Functions

Detailed Description

Member Typedef Documentation

◆ connection_hdl

◆ server

Constructor & Destructor Documentation

◆ telemetry_server()

Member Function Documentation

◆ on_close()

◆ on_http()

◆ on_open()

◆ on_timer()

◆ run()

◆ set_timer()