Refactor WebSocket, HTTP examples:

fix #297, fix #488

* Errors are checked and reported
* More comments explaining what is going on
* The connection is gracefully closed

WebSocket:

* Messages are drained before closing

CHANGELOG.md

@@ -7,6 +7,7 @@ Version 61:
 * Add message::header_part()
 * Tidy up names in error categories
 * Flush the output stream in the example
+* Clean close in Secure WebSocket client
 
 API Changes:
 

README.md

@@ -144,77 +144,9 @@ The files in the repository are laid out thusly:
 ## Usage
 
 These examples are complete, self-contained programs that you can build
-and run yourself (they are in the `examples` directory).
+and run yourself (they are in the `example` directory).
 
-Example WebSocket program:
-```C++
-#include <beast/core.hpp>
-#include <beast/websocket.hpp>
-#include <boost/asio.hpp>
-#include <iostream>
-#include <string>
-
-int main()
-{
-    // Normal boost::asio setup
-    std::string const host = "echo.websocket.org";
-    boost::asio::io_service ios;
-    boost::asio::ip::tcp::resolver r{ios};
-    boost::asio::ip::tcp::socket sock{ios};
-    boost::asio::connect(sock,
-        r.resolve(boost::asio::ip::tcp::resolver::query{host, "80"}));
-
-    // WebSocket connect and send message using beast
-    beast::websocket::stream<boost::asio::ip::tcp::socket&> ws{sock};
-    ws.handshake(host, "/");
-    ws.write(boost::asio::buffer(std::string("Hello, world!")));
-
-    // Receive WebSocket message, print and close using beast
-    beast::multi_buffer b;
-    beast::websocket::opcode op;
-    ws.read(op, b);
-    ws.close(beast::websocket::close_code::normal);
-    std::cout << beast::buffers(b.data()) << "\n";
-}
-```
-
-Example HTTP program:
-```C++
-#include <beast/core.hpp>
-#include <beast/http.hpp>
-#include <boost/asio.hpp>
-#include <boost/lexical_cast.hpp>
-#include <iostream>
-#include <string>
-
-int main()
-{
-    // Normal boost::asio setup
-    std::string const host = "www.example.com";
-    boost::asio::io_service ios;
-    boost::asio::ip::tcp::resolver r{ios};
-    boost::asio::ip::tcp::socket sock{ios};
-    boost::asio::connect(sock,
-        r.resolve(boost::asio::ip::tcp::resolver::query{host, "http"}));
-
-    // Send HTTP request using beast
-    beast::http::request<beast::http::string_body> req;
-    req.method(beast::http::verb::get);
-    req.target("/");
-    req.version = 11;
-    req.insert(beast::http::field::host, host + ":" +
-        boost::lexical_cast<std::string>(sock.remote_endpoint().port()));
-    req.insert(beast::http::field::user_agent, "Beast");
-    req.prepare();
-    beast::http::write(sock, req);
-
-    // Receive and print HTTP response using beast
-    beast::flat_buffer b;
-    beast::http::response<beast::http::dynamic_body> res;
-    beast::http::read(sock, b, res);
-    std::cout << res << std::endl;
-}
-```
+http://vinniefalco.github.io/beast/beast/quick_start.html
 
 ## License
 

example/http-client/http_client.cpp

@@ -11,35 +11,75 @@
 #include <beast/http.hpp>
 #include <boost/asio.hpp>
 #include <boost/lexical_cast.hpp>
+#include <cstdlib>
 #include <iostream>
 #include <string>
 
 int main()
 {
-    // Normal boost::asio setup
-    std::string const host = "www.example.com";
+    // A helper for reporting errors
+    auto const fail =
+        [](std::string what, beast::error_code ec)
+        {
+            std::cerr << what << ": " << ec.message() << std::endl;
+            std::cerr.flush();
+            return EXIT_FAILURE;
+        };
+
+    boost::system::error_code ec;
+
+    // Set up an asio socket
     boost::asio::io_service ios;
     boost::asio::ip::tcp::resolver r{ios};
     boost::asio::ip::tcp::socket sock{ios};
-    boost::asio::connect(sock,
-        r.resolve(boost::asio::ip::tcp::resolver::query{host, "http"}));
 
-    // Send HTTP request using beast
+    // Look up the domain name
+    std::string const host = "www.example.com";
+    auto const lookup = r.resolve(boost::asio::ip::tcp::resolver::query{host, "http"}, ec);
+    if(ec)
+        return fail("resolve", ec);
+
+    // Make the connection on the IP address we get from a lookup
+    boost::asio::connect(sock, lookup, ec);
+    if(ec)
+        return fail("connect", ec);
+
+    // Set up an HTTP GET request message
     beast::http::request<beast::http::string_body> req;
     req.method(beast::http::verb::get);
     req.target("/");
     req.version = 11;
-    req.insert(beast::http::field::host, host + ":" +
+    req.set(beast::http::field::host, host + ":" +
         boost::lexical_cast<std::string>(sock.remote_endpoint().port()));
-    req.insert(beast::http::field::user_agent, "Beast");
+    req.set(beast::http::field::user_agent, "Beast");
     req.prepare();
-    beast::http::write(sock, req);
 
-    // Receive and print HTTP response using beast
+    // Write the HTTP request to the remote host
+    beast::http::write(sock, req, ec);
+    if(ec)
+        return fail("write", ec);
+
+    // This buffer is used for reading and must be persisted
     beast::flat_buffer b;
+
+    // Declare a container to hold the response
     beast::http::response<beast::http::dynamic_body> res;
-    beast::http::read(sock, b, res);
+
+    // Read the response
+    beast::http::read(sock, b, res, ec);
+    if(ec)
+        return fail("read", ec);
+
+    // Write the message to standard out
     std::cout << res << std::endl;
+
+    // Gracefully close the socket
+    sock.shutdown(boost::asio::ip::tcp::socket::shutdown_both, ec);
+    if(ec)
+        return fail("shutdown", ec);
+
+    // If we get here then the connection is closed gracefully
+    return EXIT_SUCCESS;
 }
 
 //]

example/ssl-http-client/ssl_http_client.cpp

@@ -15,48 +15,77 @@
 
 int main()
 {
-    using boost::asio::connect;
-    using socket = boost::asio::ip::tcp::socket;
-    using resolver = boost::asio::ip::tcp::resolver;
-    using io_service = boost::asio::io_service;
-    namespace ssl = boost::asio::ssl;
+    // A helper for reporting errors
+    auto const fail =
+        [](std::string what, beast::error_code ec)
+        {
+            std::cerr << what << ": " << ec.message() << std::endl;
+            std::cerr.flush();
+            return EXIT_FAILURE;
+        };
+
+    boost::system::error_code ec;
 
     // Normal boost::asio setup
-    std::string const host = "localhost";
-    io_service ios;
-    resolver r{ios};
-    socket sock{ios};
-    connect(sock, r.resolve(resolver::query{host, "1007"}));
+    boost::asio::io_service ios;
+    boost::asio::ip::tcp::resolver r{ios};
+    boost::asio::ip::tcp::socket sock{ios};
+
+    // Look up the domain name
+    std::string const host = "www.example.com";
+    auto const lookup = r.resolve(boost::asio::ip::tcp::resolver::query{host, "https"}, ec);
+    if(ec)
+        return fail("resolve", ec);
+
+    // Make the connection on the IP address we get from a lookup
+    boost::asio::connect(sock, lookup, ec);
+    if(ec)
+        return fail("connect", ec);
+
+    // Wrap the now-connected socket in an SSL stream
+    boost::asio::ssl::context ctx{boost::asio::ssl::context::sslv23};
+    boost::asio::ssl::stream<boost::asio::ip::tcp::socket&> stream{sock, ctx};
+    stream.set_verify_mode(boost::asio::ssl::verify_none);
 
     // Perform SSL handshaking
-    ssl::context ctx{ssl::context::sslv23};
-    ssl::stream<socket&> stream{sock, ctx};
-    stream.set_verify_mode(ssl::verify_none);
-    stream.handshake(ssl::stream_base::client);
+    stream.handshake(boost::asio::ssl::stream_base::client, ec);
+    if(ec)
+        return fail("handshake", ec);
 
-    // Send HTTP request over SSL using Beast
+    // Set up an HTTP GET request message
     beast::http::request<beast::http::string_body> req;
     req.method(beast::http::verb::get);
     req.target("/");
     req.version = 11;
-    req.insert(beast::http::field::host, host + ":" +
+    req.set(beast::http::field::host, host + ":" +
         boost::lexical_cast<std::string>(sock.remote_endpoint().port()));
-    req.insert(beast::http::field::user_agent, "Beast");
+    req.set(beast::http::field::user_agent, "Beast");
     req.prepare();
-    beast::http::write(stream, req);
 
-    // Receive and print HTTP response using Beast
+    // Write the HTTP request to the remote host
+    beast::http::write(stream, req, ec);
+    if(ec)
+        return fail("write", ec);
+
+    // This buffer is used for reading and must be persisted
     beast::flat_buffer b;
-    beast::http::response<beast::http::dynamic_body> resp;
-    beast::http::read(stream, b, resp);
-    std::cout << resp;
+
+    // Declare a container to hold the response
+    beast::http::response<beast::http::dynamic_body> res;
+
+    // Read the response
+    beast::http::read(stream, b, res, ec);
+    if(ec)
+        return fail("read", ec);
+
+    // Write the message to standard out
+    std::cout << res << std::endl;
 
     // Shut down SSL on the stream
-    boost::system::error_code ec;
     stream.shutdown(ec);
     if(ec && ec != boost::asio::error::eof)
-        std::cout << "error: " << ec.message();
+        fail("ssl shutdown ", ec);
 
-    // Make sure everything is written before we leave main
-    std::cout.flush();
+    // If we get here then the connection is closed gracefully
+    return EXIT_SUCCESS;
 }

example/ssl-websocket-client/ssl_websocket_client.cpp

@@ -5,43 +5,102 @@
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 //
 
-#include <beast/core/ostream.hpp>
+#include <beast/core.hpp>
 #include <beast/websocket.hpp>
 #include <beast/websocket/ssl.hpp>
 #include <boost/asio.hpp>
 #include <boost/asio/ssl.hpp>
+#include <cstdlib>
 #include <iostream>
 #include <string>
 
 int main()
 {
-    using boost::asio::connect;
-    using socket = boost::asio::ip::tcp::socket;
-    using resolver = boost::asio::ip::tcp::resolver;
-    using io_service = boost::asio::io_service;
-    namespace ssl = boost::asio::ssl;
+    // A helper for reporting errors
+    auto const fail =
+        [](std::string what, beast::error_code ec)
+        {
+            std::cerr << what << ": " << ec.message() << std::endl;
+            std::cerr.flush();
+            return EXIT_FAILURE;
+        };
 
-    // Normal boost::asio setup
+    boost::system::error_code ec;
+
+    // Set up an asio socket to connect to a remote host
+    boost::asio::io_service ios;
+    boost::asio::ip::tcp::resolver r{ios};
+    boost::asio::ip::tcp::socket sock{ios};
+
+    // Look up the domain name
     std::string const host = "echo.websocket.org";
-    io_service ios;
-    resolver r{ios};
-    socket sock{ios};
-    connect(sock, r.resolve(resolver::query{host, "https"}));
+    auto const lookup = r.resolve(boost::asio::ip::tcp::resolver::query{host, "https"}, ec);
+    if(ec)
+        return fail("resolve", ec);
+
+    // Make the connection on the IP address we get from a lookup
+    boost::asio::connect(sock, lookup, ec);
+    if(ec)
+        return fail("connect", ec);
+
+    // Wrap the now-connected socket in an SSL stream
+    using stream_type = boost::asio::ssl::stream<boost::asio::ip::tcp::socket&>;
+    boost::asio::ssl::context ctx{boost::asio::ssl::context::sslv23};
+    stream_type stream{sock, ctx};
+    stream.set_verify_mode(boost::asio::ssl::verify_none);
 
     // Perform SSL handshaking
-    using stream_type = ssl::stream<socket&>;
-    ssl::context ctx{ssl::context::sslv23};
-    stream_type stream{sock, ctx};
-    stream.set_verify_mode(ssl::verify_none);
-    stream.handshake(ssl::stream_base::client);
+    stream.handshake(boost::asio::ssl::stream_base::client, ec);
+    if(ec)
+        return fail("ssl handshake", ec);
 
-    // Secure WebSocket connect and send message using Beast
+    // Now wrap the handshaked SSL stream in a websocket stream
     beast::websocket::stream<stream_type&> ws{stream};
-    ws.handshake(host, "/");
-    ws.write(boost::asio::buffer("Hello, world!"));
 
-    // Receive Secure WebSocket message, print and close using Beast
+    // Perform the websocket handshake
+    ws.handshake(host, "/", ec);
+    if(ec)
+        return fail("handshake", ec);
+
+    // Send a message
+    ws.write(boost::asio::buffer("Hello, world!"), ec);
+    if(ec)
+        return fail("write", ec);
+
+    // This buffer will hold the incoming message
     beast::multi_buffer b;
-    ws.close(beast::websocket::close_code::normal);
-    std::cout << beast::buffers(b.data()) << "\n";
+
+    // Read the message into our buffer
+    ws.read(b, ec);
+    if(ec)
+        return fail("read", ec);
+
+    // Send a "close" frame to the other end, this is a websocket thing
+    ws.close(beast::websocket::close_code::normal, ec);
+    if(ec)
+        return fail("close", ec);
+
+    // The buffers() function helps print a ConstBufferSequence
+    std::cout << beast::buffers(b.data()) << std::endl;
+
+    // WebSocket says that to close a connection you have
+    // to keep reading messages until you receive a close frame.
+    // Beast delivers the close frame as an error from read.
+    //
+    beast::drain_buffer drain; // Throws everything away efficiently
+    for(;;)
+    {
+        // Keep reading messages...
+        ws.read(drain, ec);
+
+        // ...until we get the special error code
+        if(ec == beast::websocket::error::closed)
+            break;
+
+        // Some other error occurred, report it and exit.
+        if(ec)
+            return fail("close", ec);
+    }
+
+    return EXIT_SUCCESS;
 }

example/websocket-client/websocket_client.cpp

@@ -10,29 +10,89 @@
 #include <beast/core.hpp>
 #include <beast/websocket.hpp>
 #include <boost/asio.hpp>
+#include <cstdlib>
 #include <iostream>
 #include <string>
 
 int main()
 {
-    // Normal boost::asio setup
-    std::string const host = "echo.websocket.org";
+    // A helper for reporting errors
+    auto const fail =
+        [](std::string what, beast::error_code ec)
+        {
+            std::cerr << what << ": " << ec.message() << std::endl;
+            std::cerr.flush();
+            return EXIT_FAILURE;
+        };
+
+    boost::system::error_code ec;
+
+    // Set up an asio socket
     boost::asio::io_service ios;
     boost::asio::ip::tcp::resolver r{ios};
     boost::asio::ip::tcp::socket sock{ios};
-    boost::asio::connect(sock,
-        r.resolve(boost::asio::ip::tcp::resolver::query{host, "80"}));
 
-    // WebSocket connect and send message using beast
+    // Look up the domain name
+    std::string const host = "echo.websocket.org";
+    auto const lookup = r.resolve(boost::asio::ip::tcp::resolver::query{host, "http"}, ec);
+    if(ec)
+        return fail("resolve", ec);
+
+    // Make the connection on the IP address we get from a lookup
+    boost::asio::connect(sock, lookup, ec);
+    if(ec)
+        return fail("connect", ec);
+
+    // Wrap the now-connected socket in a websocket stream
     beast::websocket::stream<boost::asio::ip::tcp::socket&> ws{sock};
-    ws.handshake(host, "/");
-    ws.write(boost::asio::buffer(std::string("Hello, world!")));
 
-    // Receive WebSocket message, print and close using beast
+    // Perform the websocket handhskae
+    ws.handshake(host, "/", ec);
+    if(ec)
+        return fail("handshake", ec);
+
+    // Send a message
+    ws.write(boost::asio::buffer(std::string("Hello, world!")), ec);
+    if(ec)
+        return fail("write", ec);
+
+    // This buffer will hold the incoming message
     beast::multi_buffer b;
-    ws.read(b);
-    ws.close(beast::websocket::close_code::normal);
-    std::cout << beast::buffers(b.data()) << "\n";
+
+    // Read the message into our buffer
+    ws.read(b, ec);
+    if(ec)
+        return fail("read", ec);
+
+    // Send a "close" frame to the other end, this is a websocket thing
+    ws.close(beast::websocket::close_code::normal, ec);
+    if(ec)
+        return fail("close", ec);
+
+    // The buffers() function helps print a ConstBufferSequence
+    std::cout << beast::buffers(b.data()) << std::endl;
+
+    // WebSocket says that to close a connection you have
+    // to keep reading messages until you receive a close frame.
+    // Beast delivers the close frame as an error from read.
+    //
+    beast::drain_buffer drain; // Throws everything away efficiently
+    for(;;)
+    {
+        // Keep reading messages...
+        ws.read(drain, ec);
+
+        // ...until we get the special error code
+        if(ec == beast::websocket::error::closed)
+            break;
+
+        // Some other error occurred, report it and exit.
+        if(ec)
+            return fail("close", ec);
+    }
+
+    // If we get here the connection was cleanly closed
+    return EXIT_SUCCESS;
 }
 
 //]