15 KiB
Examples
The ws folder countains many interactive programs for chat, file transfers, curl like http clients, demonstrating client and server usage.
Windows note
To use the network system on Windows, you need to initialize it once with WSAStartup() and clean it up with WSACleanup(). We have helpers for that which you can use, see below. This init would typically take place in your main function.
#include <ixwebsocket/IXNetSystem.h>
int main()
{
ix::initNetSystem();
...
ix::uninitNetSystem();
return 0;
}
WebSocket client API
#include <ixwebsocket/IXWebSocket.h>
...
// Our websocket object
ix::WebSocket webSocket;
std::string url("ws://localhost:8080/");
webSocket.setUrl(url);
// Optional heart beat, sent every 45 seconds when there is not any traffic
// to make sure that load balancers do not kill an idle connection.
webSocket.setPingInterval(45);
// Per message deflate connection is enabled by default. You can tweak its parameters or disable it
webSocket.disablePerMessageDeflate();
// Setup a callback to be fired when a message or an event (open, close, error) is received
webSocket.setOnMessageCallback([](const ix::WebSocketMessagePtr& msg)
{
if (msg->type == ix::WebSocketMessageType::Message)
{
std::cout << msg->str << std::endl;
}
}
);
// Now that our callback is setup, we can start our background thread and receive messages
webSocket.start();
// Send a message to the server (default to TEXT mode)
webSocket.send("hello world");
// The message can be sent in BINARY mode (useful if you send MsgPack data for example)
webSocket.sendBinary("some serialized binary data");
// ... finally ...
// Stop the connection
webSocket.stop()
Sending messages
websocket.send("foo") will send a message.
If the connection was closed and sending failed, the return value will be set to false.
ReadyState
getReadyState() returns the state of the connection. There are 4 possible states.
- ReadyState::Connecting - The connection is not yet open.
- ReadyState::Open - The connection is open and ready to communicate.
- ReadyState::Closing - The connection is in the process of closing.
- ReadyState::Closed - The connection is closed or could not be opened.
Open and Close notifications
The onMessage event will be fired when the connection is opened or closed. This is similar to the JavaScript browser API, which has open and close events notification that can be registered with the browser addEventListener.
webSocket.setOnMessageCallback([](const ix::WebSocketMessagePtr& msg)
{
if (msg->type == ix::WebSocketMessageType::Open)
{
std::cout << "send greetings" << std::endl;
// Headers can be inspected (pairs of string/string)
std::cout << "Handshake Headers:" << std::endl;
for (auto it : msg->headers)
{
std::cout << it.first << ": " << it.second << std::endl;
}
}
else if (msg->type == ix::WebSocketMessageType::Close)
{
std::cout << "disconnected" << std::endl;
// The server can send an explicit code and reason for closing.
// This data can be accessed through the closeInfo object.
std::cout << msg->closeInfo.code << std::endl;
std::cout << msg->closeInfo.reason << std::endl;
}
}
);
Error notification
A message will be fired when there is an error with the connection. The message type will be ix::WebSocketMessageType::Error. Multiple fields will be available on the event to describe the error.
webSocket.setOnMessageCallback([](const ix::WebSocketMessagePtr& msg)
{
if (msg->type == ix::WebSocketMessageType::Error)
{
std::stringstream ss;
ss << "Error: " << msg->errorInfo.reason << std::endl;
ss << "#retries: " << msg->eventInfo.retries << std::endl;
ss << "Wait time(ms): " << msg->eventInfo.wait_time << std::endl;
ss << "HTTP Status: " << msg->eventInfo.http_status << std::endl;
std::cout << ss.str() << std::endl;
}
}
);
start, stop
websocket.start()connect to the remote server and starts the message receiving background thread.websocket.stop()disconnect from the remote server and closes the background thread.
Configuring the remote url
The url can be set and queried after a websocket object has been created. You will have to call stop and start if you want to disconnect and connect to that new url.
std::string url("wss://example.com");
websocket.configure(url);
Ping/Pong support
Ping/pong messages are used to implement keep-alive. 2 message types exists to identify ping and pong messages. Note that when a ping message is received, a pong is instantly send back as requested by the WebSocket spec.
webSocket.setOnMessageCallback([](const ix::WebSocketMessagePtr& msg)
{
if (msg->type == ix::WebSocketMessageType::Ping ||
msg->type == ix::WebSocketMessageType::Pong)
{
std::cout << "pong data: " << msg->str << std::endl;
}
}
);
A ping message can be sent to the server, with an optional data string.
websocket.ping("ping data, optional (empty string is ok): limited to 125 bytes long");
Heartbeat.
You can configure an optional heart beat / keep-alive, sent every 45 seconds when there is no any traffic to make sure that load balancers do not kill an idle connection.
webSocket.setPingInterval(45);
Supply extra HTTP headers.
You can set extra HTTP headers to be sent during the WebSocket handshake.
WebSocketHttpHeaders headers;
headers["foo"] = "bar";
webSocket.setExtraHeaders(headers);
Subprotocols
You can specify subprotocols to be set during the WebSocket handshake. For more info you can refer to this doc.
webSocket.addSubprotocol("appProtocol-v1");
webSocket.addSubprotocol("appProtocol-v2");
The protocol that the server did accept is available in the open info protocol field.
std::cout << "protocol: " << msg->openInfo.protocol << std::endl;
Automatic reconnection
Automatic reconnection kicks in when the connection is disconnected without the user consent. This feature is on by default and can be turned off.
webSocket.enableAutomaticReconnection(); // turn on
webSocket.disableAutomaticReconnection(); // turn off
bool enabled = webSocket.isAutomaticReconnectionEnabled(); // query state
The technique to calculate wait time is called exponential
backoff. Here
are the default waiting times between attempts (from connecting with ws connect ws://foo.com)
> Connection error: Got bad status connecting to foo.com, status: 301, HTTP Status line: HTTP/1.1 301 Moved Permanently
#retries: 1
Wait time(ms): 100
#retries: 2
Wait time(ms): 200
#retries: 3
Wait time(ms): 400
#retries: 4
Wait time(ms): 800
#retries: 5
Wait time(ms): 1600
#retries: 6
Wait time(ms): 3200
#retries: 7
Wait time(ms): 6400
#retries: 8
Wait time(ms): 10000
The waiting time is capped by default at 10s between 2 attempts, but that value can be changed and queried.
webSocket.setMaxWaitBetweenReconnectionRetries(5 * 1000); // 5000ms = 5s
uint32_t m = webSocket.getMaxWaitBetweenReconnectionRetries();
WebSocket server API
#include <ixwebsocket/IXWebSocketServer.h>
...
// Run a server on localhost at a given port.
// Bound host name, max connections and listen backlog can also be passed in as parameters.
ix::WebSocketServer server(port);
server.setOnConnectionCallback(
[&server](std::shared_ptr<WebSocket> webSocket,
std::shared_ptr<ConnectionState> connectionState)
{
webSocket->setOnMessageCallback(
[webSocket, connectionState, &server](const ix::WebSocketMessagePtr msg)
{
if (msg->type == ix::WebSocketMessageType::Open)
{
std::cerr << "New connection" << std::endl;
// A connection state object is available, and has a default id
// You can subclass ConnectionState and pass an alternate factory
// to override it. It is useful if you want to store custom
// attributes per connection (authenticated bool flag, attributes, etc...)
std::cerr << "id: " << connectionState->getId() << std::endl;
// The uri the client did connect to.
std::cerr << "Uri: " << msg->openInfo.uri << std::endl;
std::cerr << "Headers:" << std::endl;
for (auto it : msg->openInfo.headers)
{
std::cerr << it.first << ": " << it.second << std::endl;
}
}
else if (msg->type == ix::WebSocketMessageType::Message)
{
// For an echo server, we just send back to the client whatever was received by the server
// All connected clients are available in an std::set. See the broadcast cpp example.
// Second parameter tells whether we are sending the message in binary or text mode.
// Here we send it in the same mode as it was received.
webSocket->send(msg->str, msg->binary);
}
}
);
}
);
auto res = server.listen();
if (!res.first)
{
// Error handling
return 1;
}
// Run the server in the background. Server can be stoped by calling server.stop()
server.start();
// Block until server.stop() is called.
server.wait();
HTTP client API
#include <ixwebsocket/IXHttpClient.h>
...
//
// Preparation
//
HttpClient httpClient;
HttpRequestArgsPtr args = httpClient.createRequest();
// Custom headers can be set
WebSocketHttpHeaders headers;
headers["Foo"] = "bar";
args->extraHeaders = headers;
// Timeout options
args->connectTimeout = connectTimeout;
args->transferTimeout = transferTimeout;
// Redirect options
args->followRedirects = followRedirects;
args->maxRedirects = maxRedirects;
// Misc
args->compress = compress; // Enable gzip compression
args->verbose = verbose;
args->logger = [](const std::string& msg)
{
std::cout << msg;
};
//
// Synchronous Request
//
HttpResponsePtr out;
std::string url = "https://www.google.com";
// HEAD request
out = httpClient.head(url, args);
// GET request
out = httpClient.get(url, args);
// POST request with parameters
HttpParameters httpParameters;
httpParameters["foo"] = "bar";
out = httpClient.post(url, httpParameters, args);
// POST request with a body
out = httpClient.post(url, std::string("foo=bar"), args);
//
// Result
//
auto statusCode = response->statusCode; // Can be HttpErrorCode::Ok, HttpErrorCode::UrlMalformed, etc...
auto errorCode = response->errorCode; // 200, 404, etc...
auto responseHeaders = response->headers; // All the headers in a special case-insensitive unordered_map of (string, string)
auto payload = response->payload; // All the bytes from the response as an std::string
auto errorMsg = response->errorMsg; // Descriptive error message in case of failure
auto uploadSize = response->uploadSize; // Byte count of uploaded data
auto downloadSize = response->downloadSize; // Byte count of downloaded data
//
// Asynchronous Request
//
bool async = true;
HttpClient httpClient(async);
auto args = httpClient.createRequest(url, HttpClient::kGet);
// Push the request to a queue,
bool ok = httpClient.performRequest(args, [](const HttpResponsePtr& response)
{
// This callback execute in a background thread. Make sure you uses appropriate protection such as mutex
auto statusCode = response->statusCode; // acess results
}
);
// ok will be false if your httpClient is not async
HTTP server API
#include <ixwebsocket/IXHttpServer.h>
ix::HttpServer server(port, hostname);
auto res = server.listen();
if (!res.first)
{
std::cerr << res.second << std::endl;
return 1;
}
server.start();
server.wait();
If you want to handle how requests are processed, implement the setOnConnectionCallback callback, which takes an HttpRequestPtr as input, and returns an HttpResponsePtr. You can look at HttpServer::setDefaultConnectionCallback for a slightly more advanced callback example.
setOnConnectionCallback(
[this](HttpRequestPtr request,
std::shared_ptr<ConnectionState> /*connectionState*/) -> HttpResponsePtr
{
// Build a string for the response
std::stringstream ss;
ss << request->method
<< " "
<< request->uri;
std::string content = ss.str();
return std::make_shared<HttpResponse>(200, "OK",
HttpErrorCode::Ok,
WebSocketHttpHeaders(),
content);
}
TLS support and configuration
To leverage TLS features, the library must be compiled with the option USE_TLS=1.
If you are using OpenSSL, try to be on a version higher than 1.1.x as there there are thread safety problems with 1.0.x.
Then, secure sockets are automatically used when connecting to a wss://* url.
Additional TLS options can be configured by passing a ix::SocketTLSOptions instance to the
setTLSOptions on ix::WebSocket (or ix::WebSocketServer or ix::HttpServer)
webSocket.setTLSOptions({
.certFile = "path/to/cert/file.pem",
.keyFile = "path/to/key/file.pem",
.caFile = "path/to/trust/bundle/file.pem", // as a file, or in memory buffer in PEM format
.tls = true // required in server mode
});
Specifying certFile and keyFile configures the certificate that will be used to communicate with TLS peers.
On a client, this is only necessary for connecting to servers that require a client certificate.
On a server, this is necessary for TLS support.
Specifying caFile configures the trusted roots bundle file (in PEM format) that will be used to verify peer certificates.
- The special value of
SYSTEM(the default) indicates that the system-configured trust bundle should be used; this is generally what you want when connecting to any publicly exposed API/server. - The special value of
NONEcan be used to disable peer verification; this is only recommended to rule out certificate verification when testing connectivity. - If the value contain the special value
-----BEGIN CERTIFICATE-----, the value will be read from memory, and not from a file. This is convenient on platforms like Android where reading / writing to the file system can be challenging without proper permissions, or without knowing the location of a temp directory.
For a client, specifying caFile can be used if connecting to a server that uses a self-signed cert, or when using a custom CA in an internal environment.
For a server, specifying caFile implies that:
- You require clients to present a certificate
- It must be signed by one of the trusted roots in the file