关于websocketpp 示例注释(https://docs.websocketpp.org/md_tutorials_utility_client_utility_client.html), 实际上是熟悉endpoint和connection，并且，两者之间关系: endpoint中关于connection相关配置在创建时拷贝道connection中，如果endpoint配置进行更新时，并不影响已经创建的connection，同时，endpoint和connection并不存在对应关系，endpoint只是负责创建和相关的配置，但是，connection负责实际的的消息交互，如示例中所示：
// 不包含TLS Client
#include <websocketpp/config/asio_no_tls_client.hpp>
#include <websocketpp/client.hpp>
// 包含TLS Client
// #include <websocketpp/config/asio_client.hpp>
// #include <websocketpp/client.hpp>
#include <websocketpp/common/thread.hpp>
#include <websocketpp/common/memory.hpp>
#include <cstdlib>
#include <iostream>
#include <map>
#include <string>
#include <sstream>
typedef websocketpp::client<websocketpp::config::asio_client> client;
// 保存一个连接的metadata
class connection_metadata {
public:
typedef websocketpp::lib::shared_ptr<connection_metadata> ptr;
connection_metadata(int id, websocketpp::connection_hdl hdl, std::string uri)
: m_id(id)
, m_hdl(hdl)
, m_status("Connecting")
, m_uri(uri)
, m_server("N/A")
{}
void on_open(client * c, websocketpp::connection_hdl hdl) {
m_status = "Open";
client::connection_ptr con = c->get_con_from_hdl(hdl);
m_server = con->get_response_header("Server");
}
void on_fail(client * c, websocketpp::connection_hdl hdl) {
m_status = "Failed";
client::connection_ptr con = c->get_con_from_hdl(hdl);
m_server = con->get_response_header("Server");
m_error_reason = con->get_ec().message();
}
void on_close(client * c, websocketpp::connection_hdl hdl) {
m_status = "Closed";
client::connection_ptr con = c->get_con_from_hdl(hdl);
std::stringstream s;
s << "close code: " << con->get_remote_close_code() << " ("
<< websocketpp::close::status::get_string(con->get_remote_close_code())
<< "), close reason: " << con->get_remote_close_reason();
m_error_reason = s.str();
}
void on_message(websocketpp::connection_hdl, client::message_ptr msg) {
if (msg->get_opcode() == websocketpp::frame::opcode::text) {
m_messages.push_back("<< " + msg->get_payload());
} else {
m_messages.push_back("<< " + websocketpp::utility::to_hex(msg->get_payload()));
}
}
websocketpp::connection_hdl get_hdl() const {
return m_hdl;
}
int get_id() const {
return m_id;
}
std::string get_status() const {
return m_status;
}
void record_sent_message(std::string message) {
m_messages.push_back(">> " + message);
}
friend std::ostream & operator<< (std::ostream & out, connection_metadata const & data);
private:
int m_id; // 表示client端中的连接的id编号
websocketpp::connection_hdl m_hdl; // websocketpp表示连接的编号
std::string m_status; // 连接自动状态
std::string m_uri; // 连接的URI
std::string m_server; // 服务器信息
std::string m_error_reason; // 错误原因
std::vector<std::string> m_messages;// 记录接收和发送的消息数据
};
std::ostream & operator<< (std::ostream & out, connection_metadata const & data) {
out << "> URI: " << data.m_uri << "\n"
<< "> Status: " << data.m_status << "\n"
<< "> Remote Server: " << (data.m_server.empty() ? "None Specified" : data.m_server) << "\n"
<< "> Error/close reason: " << (data.m_error_reason.empty() ? "N/A" : data.m_error_reason) << "\n";
out << "> Messages Processed: (" << data.m_messages.size() << ") \n";
std::vector<std::string>::const_iterator it;
for (it = data.m_messages.begin(); it != data.m_messages.end(); ++it) {
out << *it << "\n";
}
return out;
}
// 对websocketpp的 client 进行封装
class websocket_endpoint {
public:
websocket_endpoint () : m_next_id(0) {
m_endpoint.clear_access_channels(websocketpp::log::alevel::all); // 开启全部接入日志级别
m_endpoint.clear_error_channels(websocketpp::log::elevel::all); // 开启全部错误日志级别
m_endpoint.init_asio(); // 初始化asio
m_endpoint.start_perpetual(); // 避免请求为空时退出，实际上，也是避免asio退出
// 独立运行client::run()的线程，主要是避免阻塞
m_thread = websocketpp::lib::make_shared<websocketpp::lib::thread>(&client::run, &m_endpoint);
}
~websocket_endpoint() {
m_endpoint.stop_perpetual();
for (con_list::const_iterator it = m_connection_list.begin(); it != m_connection_list.end(); ++it) {
if (it->second->get_status() != "Open") {
// Only close open connections
continue;
}
std::cout << "> Closing connection " << it->second->get_id() << std::endl;
websocketpp::lib::error_code ec;
m_endpoint.close(it->second->get_hdl(), websocketpp::close::status::going_away, "", ec); // 关闭连接
if (ec) {
std::cout << "> Error closing connection " << it->second->get_id() << ": "
<< ec.message() << std::endl;
}
}
m_thread->join();
}
int connect(std::string const & uri) {
websocketpp::lib::error_code ec;
client::connection_ptr con = m_endpoint.get_connection(uri, ec); // 创建connect的共享指针，注意，此时创建并没有实际建立
if (ec) {
std::cout << "> Connect initialization error: " << ec.message() << std::endl;
return -1;
}
// 创建连接的metadata信息，并保存
int new_id = m_next_id++;
connection_metadata::ptr metadata_ptr = websocketpp::lib::make_shared<connection_metadata>(new_id, con->get_handle(), uri);
m_connection_list[new_id] = metadata_ptr;
// 注册连接打开的Handler
con->set_open_handler(websocketpp::lib::bind(
&connection_metadata::on_open,
metadata_ptr,
&m_endpoint,
websocketpp::lib::placeholders::_1
));
// 注册连接失败的Handler
con->set_fail_handler(websocketpp::lib::bind(
&connection_metadata::on_fail,
metadata_ptr,
&m_endpoint,
websocketpp::lib::placeholders::_1
));
// 注册连接关闭的Handler
con->set_close_handler(websocketpp::lib::bind(
&connection_metadata::on_close,
metadata_ptr,
&m_endpoint,
websocketpp::lib::placeholders::_1
));
// 注册连接接收消息的Handler
con->set_message_handler(websocketpp::lib::bind(
&connection_metadata::on_message,
metadata_ptr,
websocketpp::lib::placeholders::_1,
websocketpp::lib::placeholders::_2
));
// 进行连接
m_endpoint.connect(con);
return new_id;
}
void close(int id, websocketpp::close::status::value code, std::string reason) {
websocketpp::lib::error_code ec;
con_list::iterator metadata_it = m_connection_list.find(id);
if (metadata_it == m_connection_list.end()) {
std::cout << "> No connection found with id " << id << std::endl;
return;
}
// 关闭连接
m_endpoint.close(metadata_it->second->get_hdl(), code, reason, ec);
if (ec) {
std::cout << "> Error initiating close: " << ec.message() << std::endl;
}
}
void send(int id, std::string message) {
websocketpp::lib::error_code ec;
con_list::iterator metadata_it = m_connection_list.find(id);
if (metadata_it == m_connection_list.end()) {
std::cout << "> No connection found with id " << id << std::endl;
return;
}
// 连接发送数据
m_endpoint.send(metadata_it->second->get_hdl(), message, websocketpp::frame::opcode::text, ec);
if (ec) {
std::cout << "> Error sending message: " << ec.message() << std::endl;
return;
}
metadata_it->second->record_sent_message(message);
}
connection_metadata::ptr get_metadata(int id) const {
con_list::const_iterator metadata_it = m_connection_list.find(id);
if (metadata_it == m_connection_list.end()) {
return connection_metadata::ptr();
} else {
return metadata_it->second;
}
}
private:
typedef std::map<int,connection_metadata::ptr> con_list;
client m_endpoint;
websocketpp::lib::shared_ptr<websocketpp::lib::thread> m_thread; // 线程
con_list m_connection_list; // 保存全部连接的信息
int m_next_id;
};
int main() {
bool done = false;
std::string input;
websocket_endpoint endpoint;
while (!done) {
std::cout << "Enter Command: ";
std::getline(std::cin, input);
if (input == "quit") {
done = true;
} else if (input == "help") {
std::cout
<< "\nCommand List:\n"
<< "connect <ws uri>\n"
<< "send <connection id> <message>\n"
<< "close <connection id> [<close code:default=1000>] [<close reason>]\n"
<< "show <connection id>\n"
<< "help: Display this help text\n"
<< "quit: Exit the program\n"
<< std::endl;
} else if (input.substr(0,7) == "connect") {
int id = endpoint.connect(input.substr(8));
if (id != -1) {
std::cout << "> Created connection with id " << id << std::endl;
}
} else if (input.substr(0,4) == "send") {
std::stringstream ss(input);
std::string cmd;
int id;
std::string message;
ss >> cmd >> id;
std::getline(ss,message);
endpoint.send(id, message);
} else if (input.substr(0,5) == "close") {
std::stringstream ss(input);
std::string cmd;
int id;
int close_code = websocketpp::close::status::normal;
std::string reason;
ss >> cmd >> id >> close_code;
std::getline(ss,reason);
endpoint.close(id, close_code, reason);
} else if (input.substr(0,4) == "show") {
int id = atoi(input.substr(5).c_str());
connection_metadata::ptr metadata = endpoint.get_metadata(id);
if (metadata) {
std::cout << *metadata << std::endl;
} else {
std::cout << "> Unknown connection id " << id << std::endl;
}
} else {
std::cout << "> Unrecognized Command" << std::endl;
}
}
return 0;
}
来源：oschina
链接：https://my.oschina.net/u/4278787/blog/3233045