使用Nodejs实现聊天服务器

两年前在项目中使用nodejs+socket.io+redis实现的聊天和推送服务器,
基本上几百行代码就实现了整个功能，在项目中单服务器单进程可以跑到支持
5000人左右同时在线。

主要思路

1. 用户上线后，根据用户的userid和socket，保存到一个全局的map中
2. 发送消息时，根据对方的userid找到对应的socket，通过socket.emit发送消息给对方
3. 如果对方不在线，在redis中保留消息，在对方上线后推送给用户
4. 用户下线后，从全局的map中删除对应的用户socket
5. 由于需要保持长连接，客户端需要定时发心跳给服务端，所以定义了一个心跳消息，可以5分钟发一次

• 用户上线

  io.sockets.on('connection', function (socket) {
      var address = socket.handshake.address;
      console.log(Date() + " New connection from " + address.address + ":" + address.port);
      socket.on('login', function (userinfo) {
          userid = userinfo.myAuraId
          var address = socket.handshake.address;
          var deviceid = userinfo.deviceId
          console.log(Date() + " Login from " + address.address + ":" + address.port + " " + userid + " " + deviceid);
          old_socket = sockets[userid]
          if (old_socket && old_socket.deviceid && deviceid && old_socket.deviceid != deviceid) {
              old_socket.relogin = 1
              old_socket.emit('logout')
              console.log("logout " + old_socket.userid + " " + old_socket.deviceid)
          }
  
          if (old_socket && old_socket != socket) {
              old_socket.disconnect()
          }
  
          socket.relogin = 0
          socket.userid = userid
          socket.deviceid = deviceid
  		//发送离线消息
          send_store_msg(socket, userid)
  
          sockets[userid] = socket
          
          //通知业务服务器，用户已登录
          pub.publish("login_message_channel", JSON.stringify(userinfo))
  
      })
  

• 发送消息

  socket.on('chat', function (msg, ack) {
      //process_msg(msg)
      pub.publish("chat_filter_channel", JSON.stringify(msg))
      socket.userid = msg.from
      sockets[socket.userid] = socket
      if (ack) {
          ack(1)
      }
  
  })
  

• 接收和回应心跳

  socket.on('hb', function (msg, ack) {
      if (ack) {
          ack(1)
      }
  })
  

• 用户下线，删除对应的socket

  socket.on("disconnect", function () {
      var address = socket.handshake.address;
      console.log(Date() + " Disconnect from " + address.address + ":" + address.port);
      if (!socket.relogin) {
          delete sockets[socket.userid]
      }
  })
  

推送服务器

实现了聊天服务器后，对推送来说就很简单了

1. 在redis里开个channel，业务服务器往这个channel里publish数据
2. nodejs subscribe这个channel监听数据，找到对应用户发送消息即可。
3. 用户不在线，可能也需要对这个离线推送消息做保留，具体看业务定义

var notification = redis.createClient()
notification.subscribe("notification")

// check redis notifcation channel
notification.on("message", function (pattern, msg) {
    var msgobj = JSON.parse(msg)
    var keys = msgobj.toWho
    var needStore = msgobj.needStore
    for (index in keys) {
        var key = keys[index]
        if (!needStore) {
            if (sockets[key]) {
                sockets[key].emit("notification", msg)
            }
        }
        else {
            var list = []
            store.hget("nodejs_notification", key, function (e, v) {
                if (v) {
                    list = JSON.parse(v);
                }
                list.push(msg)
                var msglist = JSON.stringify(list)
                store.hset("nodejs_notification", key, msglist, function (e, r) {
                })
            })

            if (sockets[key]) {
                send_notification(sockets[key], msg)
            }

        }
    }
})

function send_notification(socket, notif) {
    socket.emit("notification", notif, function ack() {
        store.hdel("nodejs_notification", socket.userid)
    })
}

客户端Lib库

服务端是使用socket.io实现，基本上socket.io的Lib都能兼容

以下是推荐的两个客户端Lib：

• JAVA版的 socket.io (Android也可以使用)
• IOS版的 socket.io

其他语言版本，可以在github搜索socket.io,找到对应的Lib库

Server端全部代码

//var io = require('socket.io').listen(80)
var app = require('http').createServer(handler)
    , io = require('socket.io').listen(app)

app.listen(80);

function handler(req, res) {
    if (req.url == "/monitor") {
        res.writeHead(200);
        res.end("OK");
    }
    else {
        res.writeHead(404);
        res.end();
    }
}


//io.disable('heartbeats')
//io.set('heartbeats', false);
io.set('transports', ['websocket', 'xhr-polling']);
io.set('heartbeat timeout', 5 * 60)
io.set('heartbeat interval', 4 * 60)
io.set('close timeout', 1 * 30);
io.set("log level", 1)
io.set("browser client", false)
io.set("browser client cache", false)
io.set("browser client cache", false)
var redis = require("redis")
var pub = redis.createClient()
var store = redis.createClient()
var snschat = redis.createClient()
var notification = redis.createClient()
var PUSH_TO_IOS_DELAY_TIME = 120000
snschat.subscribe("snschat");
notification.subscribe("notification")
var sockets = {}

pub.on("error", function (err) {
    console.log("Error " + err);
});

store.on("error", function (err) {
    console.log("Error " + err);
});

snschat.on("error", function (err) {
    console.log("Error " + err);
});


function send_msg_delay(socket) {
    store.hget("chat_history", socket.userid, function (e, v) {
        if (v) {
            list = JSON.parse(v);
            if (list.length > 0) {
                var msg = JSON.stringify(list)
                socket.isSendingChatMessage = false
                send_msg(socket, msg)
            }
        }
    })
}

function send_msg(socket, msg) {
    //delay for 5 sec
    if (socket.isSendingChatMessage) {
        setTimeout(function () {
            send_msg_delay(socket)
        }, 5000)
        return
    }
    socket.isSendingChatMessage = true

    //start send
    var callSendToIOS = sendToIOSDealy(socket.userid, PUSH_TO_IOS_DELAY_TIME)
    socket.emit("chat", msg, function ack(size) {
        clearTimeout(callSendToIOS)
        store.hget("chat_history", socket.userid, function (e, v) {
            if (v) {
                list = JSON.parse(v);
                //console.log("size="+size)
                if (list.length == size) {
                    store.hdel("chat_history", socket.userid, function (e, r) {
                    })
                }
                else if (size < list.length) {
                    list = list.splice(size)
                    var msglist = JSON.stringify(list)
                    store.hset("chat_history", socket.userid, msglist, function (e, r) {
                    })
                }
            }
            socket.isSendingChatMessage = false

        })
    })
}


function sendToIOSDealy(toWho, time) {
    return setTimeout(function () {
        sendToIOS(toWho)
    }, time)
}

function sendToIOS(toWho) {
    var obj = {"toWho": toWho}
    var msg = JSON.stringify(obj)
    console.log("delay send to ios channel:" + msg)
    pub.publish("chat_message_channel", msg)
}

function send_notification(socket, notif) {
    socket.emit("notification", notif, function ack() {
        store.hdel("nodejs_notification", socket.userid)
    })
}

function send_store_msg(socket, userid) {

    if (socket.isSendStoreMsg) {
        return;
    }

    socket.isSendingChatMessage = false

    store.hget("chat_history", userid, function (e, msg) {
        if (msg) {
            send_msg(socket, msg)
            store.hdel("chat_history", socket.userid, function (e, r) {
            })
        }
    })

    store.hget("nodejs_notification", userid, function (e, msg) {
        if (msg) {
            var msglist = JSON.parse(msg)
            for (var i = 0; i < msglist.length; i++) {
                send_notification(socket, msglist[i])
            }
            //socket.emit("notification", msg)
            //store.hdel("nodejs_notification", userid)
        }
    })
    socket.isSendStoreMsg = true
}

function saveToChatHistory(msg) {
    var list = []
    store.hget("chat_history", msg.to, function (e, v) {
        if (v) {
            list = JSON.parse(v);
        }
        list.push(msg)
        var msglist = JSON.stringify(list)
        store.hset("chat_history", msg.to, msglist, function (e, r) {
        })
    })
}


function pushToChatHistoryChannel(msg) {
    var msgStr = JSON.stringify(msg)
    pub.publish("chat_message_history_channel", msgStr)
}

function process_msg(msg) {
    var list = []
    store.hget("chat_history", msg.to, function (e, v) {
        if (v) {
            list = JSON.parse(v);
        }
        list.push(msg)
        var msglist = JSON.stringify(list)
        store.hset("chat_history", msg.to, msglist, function (e, r) {
        })
        if (sockets[msg.to]) {
            send_msg(sockets[msg.to], msglist)
        }
        else {
            sendToIOS(msg.to)
        }
        pushToChatHistoryChannel(msg)
    })
}

// check redis notifcation channel
notification.on("message", function (pattern, msg) {
    var msgobj = JSON.parse(msg)
    var keys = msgobj.toWho
    var needStore = msgobj.needStore
    for (index in keys) {
        var key = keys[index]
        if (!needStore) {
            if (sockets[key]) {
                sockets[key].emit("notification", msg)
            }
        }
        else {
            var list = []
            store.hget("nodejs_notification", key, function (e, v) {
                if (v) {
                    list = JSON.parse(v);
                }
                list.push(msg)
                var msglist = JSON.stringify(list)
                store.hset("nodejs_notification", key, msglist, function (e, r) {
                })
            })

            if (sockets[key]) {
                send_notification(sockets[key], msg)
            }

        }
    }
})

// check redis snschat channel
snschat.on("message", function (pattern, data) {
    msg = JSON.parse(data)
    process_msg(msg)
})


io.sockets.on('connection', function (socket) {
    var address = socket.handshake.address;
    console.log(Date() + " New connection from " + address.address + ":" + address.port);
    socket.on('login', function (userinfo) {
        userid = userinfo.myAuraId
var address = socket.handshake.address;
var deviceid = userinfo.deviceId
console.log(Date() + " Login from " + address.address + ":" + address.port + " " + userid + " " + deviceid);
        old_socket = sockets[userid]
if (old_socket && old_socket.deviceid && deviceid && old_socket.deviceid != deviceid) {
            old_socket.relogin = 1
            old_socket.emit('logout')
console.log("logout " + old_socket.userid + " " + old_socket.deviceid)
        }

if (old_socket && old_socket != socket) {
            old_socket.disconnect()
        }

        socket.relogin = 0
        socket.userid = userid
        socket.deviceid = deviceid

        send_store_msg(socket, userid)

        sockets[userid] = socket
        pub.publish("login_message_channel", JSON.stringify(userinfo))

    })

    socket.on('geo', function (geo, ack) {
if (geo.myAuraId) {
var now = new Date()
            pub.publish("geo", JSON.stringify({
                geo: geo, time: now.getTime()
            }))
            socket.userid = geo.myAuraId
            sockets[socket.userid] = socket

if (ack) {
                ack(1)
                send_store_msg(socket, userid)

            }
        }
    })

    socket.on('chat', function (msg, ack) {
//process_msg(msg)
        pub.publish("chat_filter_channel", JSON.stringify(msg))
        socket.userid = msg.from
        sockets[socket.userid] = socket
if (ack) {
            ack(1)
        }

    })

    socket.on('hb', function (msg, ack) {
if (ack) {
            ack(1)
        }
    })


    socket.on("disconnect", function () {
var address = socket.handshake.address;
console.log(Date() + " Disconnect from " + address.address + ":" + address.port);
if (!socket.relogin) {
delete sockets[socket.userid]
        }
    })