监听成员上下线事件 - Websocket在线状态

前置条件

• js SDK 2.7+
• Android SDK 0.2.0+
• IOS SDK 0.2.0+
• 初始化成员在线状态

监听成员上下线事件

上下线事件总共有（action）四种类型：

• join: 上线，成员成功订阅channel
• leave: 离开，成员主动调用disconnect断开连接，或者主动调用unsubscribe方法取消该channel的订阅
• timeout: 超时，成员订阅了 channel，因为网络原因，导致连接断开
• back: 重新上线，成员订阅了channel，因为网络原因断开连接，在网络恢复后触发

如果一个成员（同一个id)同时打开了多个客户端，join和back仅在第一个客户端上线时触发， leave和timeout只会在最后一个下线的客户端下线时触发。

换句话说：

如果已经有一个客户端订阅了该channel并且当前是在线状态时，使用同一id的其他客户端上线时，不会触发上线提醒；
如果还存在一个客户端订阅了该channel并且当前是在线状态时，使用同一id的其他客户端下线时，不会触发下线提醒。

监听成员上下线事件

Javascript

    pubsub.subscribePresence({
        channel: "my_channel",
        membersLimit: 20, //可选项，定义返回的最新上线成员列表的数量，默认为10，最多支持返回100个成员
        onPresence: function (presenceEvent) {
            console.log("Presence events: ", JSON.stringify(presenceEvent));
        // {
        //     action: 'join',
        //     member: {id: 'user001', data: {avatar:'/www/xxx4.png', nickname: 'Tom'}},
        //     amount: 3000, //当前订阅该channel的在线成员总数
        //     memebers: [  //最新上线的20个成员列表
        //         {id: 'user001', data: {avatar:'/www/xxx1.png', nickname: 'Neo'}},                        
        //         {id: 'user002', data: {avatar:'/www/xxx2.png', nickname: 'Lucy'}},   
        //          ....    
        //         {id: 'user003', data: {avatar:'/www/xxx3.png', nickname: 'Jack'}},     
        //     ]
        // }
        },
        onSuccess: function () {  //监听成功
            console.log("subscribe presence successfully.")
        },
        onFailed: function (error) { //监听失败
            console.log("Failed to subscribe presence, code:" + error.code + ",error:" + error.content);
        },
    });

Android

    val subscribePresenceOptions = SubscribePresenceOptions(
        channel = "my_channel",
        membersLimit = 20, //可选项，定义返回的最新上线成员列表的数量，默认为10，最多支持返回100个成员
        onPresence = {event:PresenceEvent ->
            /** PresenceEvent:
                action: String
                amount: Int
                member: Member
                    - id: String
                    - data: Map<String, Any>
                members: List<Member>
            */
        },
        onSuccess = {
            Log.i("Channel","subscribePresence success")
        },
        onFailed = { error ->
            Log.i("Channel","subscribePresence failed: code: ${error.code} data: ${error.data}")
        }
    )
    GPubSub.subscribePresence(subscribePresenceOptions)

iOS

    let subscribePresenceOptions = SubscribePresenceOptions(
        channel: "my_channel",
        membersLimit: 20, //可选项，定义返回的最新上线成员列表的数量，默认为10，最多支持返回100个成员
        onPresence: { event in
            /** PresenceEvent:
                action: String
                amount: Int32
                member: Member
                    - id: String
                    - data: [String: Any]
                members: [Member]
            */
        },
        onSuccess:{
            print("subscribePresence success")
        },
        onFailed:{ result in
            print("subscribePresence failed: code:\(result.code) data:\(result.data)")
        }
    )
    GPubSub.subscribePresence(options: subscribePresenceOptions)

取消监听成员上下线事件

Javascript

    pubsub.unsubscribePresence({
        channel: "my_channel",
        onSuccess: function () {  //取消监听成功
            console.log("unsubscribe presence successfully.")
        },
        onFailed: function (error) { //监听失败
            console.log("Failed to unsubscribe presence, code:" + error.code + ",error:" + error.content);
        },
    });

Android

    val unSubscribePresenceOptions = UnSubscribePresenceOptions(
        channel = "my_channel",
        onSuccess = {
            Log.i("Channel","取消订阅上下线成功")
        },
        onFailed = { error ->
            Log.i("Channel","取消订阅上下线失败: code: ${error.code} data: ${error.data}")
        }
    )
    GPubSub.unsubscribePresence(unSubscribePresenceOptions)

iOS

    let unSubscribePresenceOptions = UnSubscribePresenceOptions(
        channel: "my_channel",
        onSuccess:{
            print("取消订阅上下线成功")
        },
        onFailed:{ result in
            print("取消订阅上下线失败: code:\(result.code) data:\(result.data)")
        }
    )
    GPubSub.unsubscribePresence(options: unSubscribePresenceOptions)

资费

1. GoEasy每触发一次presenceEvent，扣减消息数1条
2. 每个客户端收到一次presenceEvent，扣减消息数1条