Solution for Maintaining Room Stream List via Callbacks

Operation scenario

When developers frequently publish streams and stop publishing streams within a short period of time, the Stream Created Callback and Stream Destroyed Callback provided by ZEGO do not guarantee that the order of results is consistent with the order of execution by the developer.

When developers need to rely on the Stream Created Callback and Stream Destroyed Callback to maintain a local room stream list, the inconsistency between the callback order and the execution order may cause some business errors.

For example, the user's behavior order is:

1. User u1 logs in to room r1;
2. User u1 publishes stream s1, triggering stream created callback sc1;
3. User u1 stops publishing stream s1, triggering stream destroyed callback sc2;
4. User u1 publishes stream s1 again, triggering stream created callback sc3.

After passing through the callback service, the order of reaching the developer's server may become:

1. Stream created callback sc1 when user u1 publishes stream s1;
2. Stream created callback sc3 when user u1 publishes stream s1 again;
3. Stream destroyed callback sc2 when user u1 stops publishing stream s1.

The developer updates the local room stream list information based on the order of callbacks. Stream s1 will be deleted, but in fact stream s1 is still in room r1.

Operation steps

To solve the problems caused by the above callback out-of-order, ZEGO recommends that developers combine Solution for Maintaining Room List via Callbacks and refer to the following solution to maintain the local room user list.

Pay attention to key callback parameters

Pay attention to the key parameters of Stream Created Callback and Stream Destroyed Callback.

Maintain local room stream list

Maintain the local room stream list based on stream_id, stream_sid, create_time_ms, stream_seq, and the corresponding room's room_id and room_session_id.

The data structure of the local room stream list is as follows:

{
    RoomInfo: {//Refer to "Solution for Maintaining Room List via Callbacks"
        RoomID: room_id,
        RoomSessionId: room_session_id,
        RoomCreateTime:room_create_time,
        ...//Other data that needs to be saved for business
    },
    StreamList:[
        {
            StreamId:stream_id_1,
            StreamSid:session_sid_1,
            StreamCreateTime:create_time_ms_1,
            StreamSeq:stream_seq_1
            ...//Other data that needs to be saved for business
        },{
            StreamId:stream_id_2,
            StreamSid:session_sid_2,
            StreamCreateTime:create_time_ms_2,
            StreamSeq:stream_seq_2
            ...//Other data that needs to be saved for business
        }
    ]
}

{
    RoomInfo: {//Refer to "Solution for Maintaining Room List via Callbacks"
        RoomID: room_id,
        RoomSessionId: room_session_id,
        RoomCreateTime:room_create_time,
        ...//Other data that needs to be saved for business
    },
    StreamList:[
        {
            StreamId:stream_id_1,
            StreamSid:session_sid_1,
            StreamCreateTime:create_time_ms_1,
            StreamSeq:stream_seq_1
            ...//Other data that needs to be saved for business
        },{
            StreamId:stream_id_2,
            StreamSid:session_sid_2,
            StreamCreateTime:create_time_ms_2,
            StreamSeq:stream_seq_2
            ...//Other data that needs to be saved for business
        }
    ]
}

Processing judgment logic

After receiving the Stream Created Callback and Stream Destroyed Callback, update the local room list.

The field descriptions in the images below are as follows:

• Stream created callback processing flow:

• Stream destroyed callback processing flow: