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WebRTC WebSocket Messaging Details

Ahmet Oğuz Mermerkaya edited this page Feb 14, 2019 · 13 revisions

This documentation is for developers who needs to implement signalling between Ant Media Server and clients for publishing & playing streams. Let's make it step by step

Publishing WebRTC Stream

  1. Client connects to Ant Media Server through WebSocket. URL of the WebSocket interface is something like
ws://SERVER_NAME:5080/WebRTCAppEE/websocket
  1. Client sends publish JSON command to the server with stream name parameter. (Remove token parameter if token control is not enabled)
{
    command : "publish",
    streamId : "stream1",
    token : "tokenId",
}
  1. If Server accepts the stream, it replies back with start command
{
    command : "start",
    streamId : "stream1",
}
  1. Client inits peer connections, creates offer sdp and send the sdp configuration to the server with takeConfiguration command
{
   command : "takeConfiguration",
   streamId : "stream1",
   type : "offer",  
   sdp : "${SDP_PARAMETER}"
}
  1. Server creates answer sdp and send the sdp configuration to the client with takeConfiguration command
{
   command : "takeConfiguration",
   streamId : "stream1",
   type : "answer",  
   sdp : "${SDP_PARAMETER}"
}
  1. Client and Server get ice candidates several times and sends to each other with takeCandidate command
{
    command : "takeCandidate",
    streamId : "stream1",
    label : "${CANDIDATE.SDP_MLINE_INDEX}",
    id : "${CANDIDATE.SDP_MID}",
    candidate : "${CANDIDATE.CANDIDATE}"
}
  1. Clients sends stop JSON command to stop publishing
{
    command : "stop",
    streamId: "stream1"
}

Playing WebRTC Stream

  1. Client connects to Ant Media Server through WebSocket.
ws://SERVER_NAME:5080/WebRTCAppEE/websocket
  1. Client sends play JSON command to the server with stream name parameter. (Remove token parameter if token control is not enabled)
{
    command : "play",
    streamId : "stream1",
    token : "tokenId",

}
  1. If Server accepts the stream, it replies back with offer command
{
   command : "takeConfiguration",
   streamId : "stream1",
   type : "offer",  
   sdp : "${SDP_PARAMETER}"
}
  1. Client creates answer sdp and send the sdp configuration to the server with takeConfiguration command
{
   command : "takeConfiguration",
   streamId : "stream1",
   type : "answer",  
   sdp : "${SDP_PARAMETER}"
}
  1. Client and Server get ice candidates several times and sends to each other with takeCandidate command
{
    command : "takeCandidate",
    streamId : "stream1",
    label : "${CANDIDATE.SDP_MLINE_INDEX}",
    id : "${CANDIDATE.SDP_MID}",
    candidate : "${CANDIDATE.CANDIDATE}"
}
  1. Clients sends stop JSON command to stop playing
{
    command : "stop",
    streamId: "stream1",
}

Peer to Peer WebRTC Stream

  1. Peers connects to Ant Media Server through WebSocket.
ws://SERVER_NAME:5080/WebRTCAppEE/websocket
  1. Client sends join JSON command to the server with stream name parameter.
{
    command : "join",
    streamId : "stream1",
}

If there is only one peer in the stream1, server waits for the other peer to join the room.

  1. When second peer joins the stream, server sends start JSON command to the first peer
{
    command : "start",
    streamId : "stream1",
}
  1. First peer create offer sdp and send to the server with takeConfiguration command,
{
   command : "takeConfiguration",
   streamId : "stream1",
   type : "offer",  
   sdp : "${SDP_PARAMETER}"
}

Server relays the offer sdp to the second peer

  1. Second peer creates answer sdp and sends to the server with takeConfiguration command
{
   command : "takeConfiguration",
   streamId : "stream1",
   type : "answer",  
   sdp : "${SDP_PARAMETER}"
}

Server relays the answer sdp to the first peer

  1. Each peers get ice candidates several times and sends to each other with takeCandidate command through server
{
    command : "takeCandidate",
    streamId : "stream1",
    label : "${CANDIDATE.SDP_MLINE_INDEX}",
    id : "${CANDIDATE.SDP_MID}",
    candidate : "${CANDIDATE.CANDIDATE}"
}
  1. Clients sends leave JSON command to leave the room
{
    command : "leave",
    streamId: "stream1"
}

Conference WebRTC Stream

  1. Peers connects to Ant Media Server through WebSocket.
ws://SERVER_NAME:5080/WebRTCAppEE/websocket
  1. Client sends join JSON command to the server with room name parameter.
{
    command : "joinRoom",
    room : "room1",
}
  1. Server notifies the client with available streams in the room
{
    command : "notification",
    definition : "joinedTheRoom",
    streamId: "unique_stream_id_returned_by_the_server"
    streams: [
        "stream1_in_the_room",
        "stream2_in_the_room",
        .
        .
        .
    ]
}

streamId returned by the server is the stream id client uses to publish stream to the room. streams is the json array which client can play via WebRTC. Client can play each stream by play method above. This strams array can be empty if there is no stream in the room.

  1. When there is a new guy joined the room, server sends below message to each peer in the room.
{
    command : "notification",
    definition : "streamJoined",
    streamId: "new_stream_id_joined_the_room"
    
}

Client can play the new joined stream with the streamId by the play method above.

  1. When someone leaves the room, server sends the below message to each peer in the room.
{
    command : "notification",
    definition : "streamLeaved",
    streamId: "stream_id_leaved_the_room"
}

Client can update/remove the related video views from UI.

  1. Any user can leave the room by sending below message
{
    command : "leaveFromRoom",
    room: "roomName"
}

WebSocket Error Callbacks

  • noStreamNameSpecified: it is sent when stream id is not specified in the message.
{
    command : "error",
    definition : "noStreamNameSpecified",
}
  • not_allowed_unregistered_streams: This is sent back to the user if the publisher wants to send a stream with an unregistered id and server is configured not to allow this kind of streams
{
    command : "error",
    definition: "not_allowed_unregistered_streams",
}
  • no_room_specified: This is sent back to the user when there is no room specified in joining the video conference.
{
    command : "error",
    definition : "no_room_specified",
}
  • unauthorized_access:This is sent back to the user when the token is not validated
{
    command : "error",
    definition : "unauthorized_access",
}
  • no_encoder_settings:This is sent back to the user when there are no encoder settings available in publishing the stream.
{
    command : "error",
    definition : "no_encoder_settings",
}
  • no_peer_associated_before: This is peer to peer connection error definition.It is sent back to the user when there is no peer associated with the stream.
{
    command : "error",
    definition : "no_peer_associated_before",
}
  • notSetLocalDescription: It is send when local description is not set successfully
{
    command : "error",
    definition : "notSetLocalDescription",
}

Check WebRTC Connected with Ping/Pong

Whenever you send a ping command to the server, it will respond you with pong command. Ping Command

{
    command : "ping",
}

Pong Response from Server

{
    command : "pong",
}
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