uWebSockets是一个用C++17标准实现的网络库，底层使用的自行实现的uSockets做网络处理，是一个高性能、多平台兼容的开源项目。地址：uWebSockets: Simple, secure & standards compliant web server for the most demanding of applications
示例代码
整个项目以C++17以下标准语法进行编写的，然而为了美观，示例中的初始化部分使用了C++20标准。
/* One app per thread; spawn as many as you have CPU-cores and let uWS share the listening port */
uWS::SSLApp({
/* These are the most common options, fullchain and key. See uSockets for more options. */
.cert_file_name = "cert.pem",
.key_file_name = "key.pem"
}).get("/hello/:name", [](auto *res, auto *req) {
/* You can efficiently stream huge files too */
res->writeStatus("200 OK")
->writeHeader("Content-Type", "text/html; charset=utf-8")
->write("<h1>Hello ")
->write(req->getParameter("name"))
->end("!</h1>");
}).ws<UserData>("/*", {
/* Just a few of the available handlers */
.open = [](auto *ws) {
ws->subscribe("oh_interesting_subject");
},
.message = [](auto *ws, std::string_view message, uWS::OpCode opCode) {
ws->send(message, opCode);
}
}).listen(9001, [](auto *listenSocket) {
if (listenSocket) {
std::cout << "Listening on port " << 9001 << std::endl;
} else {
std::cout << "Failed to load certs or to bind to port" << std::endl;
}
}).run();
问题：初始化部分
可以看如下部分：
ws<UserData>("/*", {
/* Just a few of the available handlers */
.open = [](auto *ws) {
ws->subscribe("oh_interesting_subject");
},
.message = [](auto *ws, std::string_view message, uWS::OpCode opCode) {
ws->send(message, opCode);
}
此处用到了带”.”的初始化方法，仅对结构体中的部分内容赋值，而这种语法在C++20以前是不支持的。不巧的是有一些库，比如openCV并不支持C++20语法，在集成的时候会出现问题。因此需要对这个初始化方法进行修改。
无论是SSLApp还是App对象，均是从TemplatedApp而来，在TemplatedApp中定义了ws对象的初始化方法，即传入一个结构体WebSocketBehavior。
template <typename UserData>
struct WebSocketBehavior {
/* Disabled compression by default - probably a bad default */
CompressOptions compression = DISABLED;
/* Maximum message size we can receive */
unsigned int maxPayloadLength = 16 * 1024;
/* 2 minutes timeout is good */
unsigned short idleTimeout = 120;
/* 64kb backpressure is probably good */
unsigned int maxBackpressure = 64 * 1024;
bool closeOnBackpressureLimit = false;
/* This one depends on kernel timeouts and is a bad default */
bool resetIdleTimeoutOnSend = false;
/* A good default, esp. for newcomers */
bool sendPingsAutomatically = true;
/* Maximum socket lifetime in minutes before forced closure (defaults to disabled) */
unsigned short maxLifetime = 0;
MoveOnlyFunction<void(HttpResponse<SSL> *, HttpRequest *, struct us_socket_context_t *)> upgrade = nullptr;
MoveOnlyFunction<void(WebSocket<SSL, true, UserData> *)> open = nullptr;
MoveOnlyFunction<void(WebSocket<SSL, true, UserData> *, std::string_view, OpCode)> message = nullptr;
MoveOnlyFunction<void(WebSocket<SSL, true, UserData> *, std::string_view, OpCode)> dropped = nullptr;
MoveOnlyFunction<void(WebSocket<SSL, true, UserData> *)> drain = nullptr;
MoveOnlyFunction<void(WebSocket<SSL, true, UserData> *, std::string_view)> ping = nullptr;
MoveOnlyFunction<void(WebSocket<SSL, true, UserData> *, std::string_view)> pong = nullptr;
MoveOnlyFunction<void(WebSocket<SSL, true, UserData> *, std::string_view, int, int)> subscription = nullptr;
MoveOnlyFunction<void(WebSocket<SSL, true, UserData> *, int, std::string_view)> close = nullptr;
};
//·········//
template <typename UserData>
TemplatedApp &&ws(std::string pattern, WebSocketBehavior<UserData> &&behavior) {
//·········//
}
在外部来构造这个WebSocketBehavior变量有一个小坑，构造方式如下：
uWS::App::WebSocketBehavior<std::string> behavior;
behavior.open = [this](auto *ws){ onOpen(ws); };
behavior.message = [this](auto *ws, std::string_view message, uWS::OpCode opCode){ onMessage(ws, message, opCode);};
behavior.close = [this](auto *ws, int code, std::string_view message){ onClose(ws, code, message);};
this->ws<std::string>("/*", std::move(behavior))
.listen(port, [&](auto *token)
{
if (token) {
LOG_INFO("{0}: WebSocket server is listening on port {1}", "wsServer", port);
} else {
LOG_ERROR("{0}: Failed to listen on port {1}", "wsServer", port);
} })
.run();
重点就在这个结构体的定义：uWS::App::WebSocketBehavior<std::string> behavior;
文档信息
- 本文作者：Xiangxu
- 本文链接：http://blog.xxsay.online/2025/02/20/uWebSockets-usage/
- 版权声明：自由转载-非商用-非衍生-保持署名（创意共享3.0许可证）