Janus源碼分析（4）——信令交互過程

1. Janus插件交互流程

Janus中所有插件都遵循以下基本數據流程：

1. 客戶端發送create創建一個Janus會話；
2. Janus回覆success返回Janus會話句柄；
3. 客戶端發送attach命令在Janus會話上attach指定插件；
4. Janus回覆success返回插件的句柄；
5. 客戶端給指定的插件發送message進行信令控制；
6. Janus上的插件發送event通知事件給客戶端；
7. 客戶端收集candidate並通過trickle消息發送給插件綁定的ICE通道；
8. Janus發送webrtcup通知ICE通道建立；
9. 客戶端發送媒體數據；
10. Janus發送media消息通知媒體數據的第一次到達；
11. Janus進行媒體數據轉發。

2. Janus信令交互過程

2.1 客戶端與Janus信令交互

• Janus客戶端->Janus網關: Janus客戶端發送create請求創建會話

{
	"janus": "create",
	"transaction": "XoldN2OmUa3r
}

• Janus網關–>>Janus客戶端: Janus網關創建會話，並返回會話ID

{
	"janus": "success",
	"transaction": "XoldN2OmUa3r,
	"data": {
		"id": 7147844471131709
	}
}

• Janus客戶端->Janus網關: Janus客戶端發送attach請求使用插件

{
	"janus": "attach",
	"plugin": "janus.plugin.videoroom",
	"session_id": 7147844471131709,
	"transaction": "zZxl_ZT7tFwTU"
}

• Janus網關–>>Janus客戶端: Janus網關查找插件，並返回插件ID

{
	"janus": "success",
	"session_id": 7147844471131709,
	"transaction": "zZxl_ZT7tFwTU",
	"data": {
		"id": 7668325947218508
	}
}

• Janus客戶端->Janus網關: Janus客戶端給指定插件發送message（Join）

{
	"janus": "message",
	"session_id": 7147844471131709,
	"handle_id": 7668325947218508
	"transaction": "AblncRsrMM3T",
	"body": {
		"request": "join",
		"room": 1234,
		"ptype": "publisher",
		"display": "ban"
	}
}

• Janus網關–>>Janus客戶端: Janus網關返回ack消息

{
	"janus": "ack",
	"session_id": 7147844471131709,
	"transaction": "AblncRsrMM3T"
}

• Janus網關–>>Janus客戶端: Janus網關處理message，並將結果通過event事件發送給客戶端

{
	"janus": "event",
	"session_id": 7147844471131709,
	"transaction": "AblncRsrMM3T",
	"sender": 7668325947218508,
	"plugindata": {
		"plugin": "janus.plugin.videoroom",
		"data": {
			"videoroom": "joined",
			"room": 1234,
			"description": "Demo Room",
			"id": 8177683424697792,
			"private_id": 1508384900,
			"publishers":[]
		}
	}
}

• Janus客戶端->Janus網關: Janus客戶端給指定插件發送message（Configure & offer）

{
	"janus": "message",
	"session_id": 7147844471131709,
	"handle_id": 7668325947218508,
	"transaction": "QvOYptHlhVOl",
	"body": {
		"request": "configure",
		"audio": true,
		"video": true
	},
	"jsep": {
		"sdp": "......",
		"type": "offer"
	}
}

• Janus客戶端->Janus網關: Janus客戶端給指定插件發送trickle（Candidate）

{
	"candidate": {
		"candidate": "candidate:2202484529 1 udp 2122262783 2409:8805:85e3:2dd9:l:l:al91:925c 55527 typ host generation 0",
		"sdpMid": "audio",
		"sdpMLinelndex": 0
	},
	"janus": "trickle",
	"session_id": 7147844471131709,
	"handle_id": 7668325947218508,
	"transaction": "A39mtuEYv9cR"
}

{
	"candidate": {
		"candidate": "candidate:2530088836 1 udp 2122194687 192.168.1.106 33864 typ host generation 0",
		"sdpMid": "audio",
		"sdpMLinelndex": 0
	}
	"janus": "trickle",
	"session_id": 7147844471131709,
	"handle_id": 7668325947218508,
	"transaction": "qFvztALbkXUG"
}

{
	"candidate": {
		"candidate": "candidate:2202484529 2 udp 2122262782 2409:8805:85e3:2dd9:l:l:al91:925c 42873 typ host generation 0",
		"sdpMid": "audio",
		"sdpMLinelndex": 0
	},
	"janus": "trickle",
	"session_id": 7147844471131709,
	"handle_id": 7668325947218508,
	"transaction": "VOzahdOJx6pn"
}

{
	"candidate": {
		"candidate": "candidate:2530088836 2 udp 2122194686 192.168.1.106 44575 typ host generation 0",
		"sdpMid": "audio",
		"sdpMLinelndex": 0
	},
	"janus": "trickle",
	"session_id": 7147844471131709,
	"handle_id": 7668325947218508,
	"transaction": "spupMHelabw8"
}

• Janus網關–>>Janus客戶端: Janus網關返回message（Configure & offer）的ack消息

{
	"janus": "ack",
	"session_id": 7147844471131709,
	"transaction": "QvOYptHlhVOl"
}

• Janus網關–>>Janus客戶端: Janus網關處理message（Configure & offer），並將answer通過event事件發送給客戶端

{
	"janus": "event",
	"session_id": 7147844471131709,
	"transaction": "Qv0YptHlhVOl"
	"sender": 7668325947218508,
	"plugindata": {
		"plugin": "janus.plugin.videoroom",
		"data": {
			"videoroom": "event",
			"room": 1234,
			"configured": "ok"
			"audio_codec": "opus",
			"video_codec": "h264"
		}
	},
	"jsep":{
		"type": "answer",
		"sdp": "......"
	}
}

• Janus網關–>>Janus客戶端: Janus網關返回ack消息

{
	"janus": "ack",
	"session_id": 7147844471131709,
	"transaction": "A39mtuEYv9cR"
}

{
	"janus": "ack",
	"session_id": 7147844471131709,
	"transaction": "qFvztALbkXUG"
}

{
	"janus": "ack",
	"session_id": 7147844471131709,
	"transaction": "VOzahdOJx6pn"
}

{
	"janus": "ack",
	"session_id": 7147844471131709,
	"transaction": "spupMHelabw8"
}

• Janus客戶端->Janus網關: Janus客戶端給指定插件發送trickle（Candidate Complete）

{
	"candidate": {
		"completed": true
	}
	"janus": "trickle",
	"session_id": 7147844471131709,
	"handle_id": 7668325947218508,
	"transaction": "43XefXDPTPMX"
}

• Janus網關–>>Janus客戶端: Janus網關返回trickle（Candidate Complete）的ack消息

{
	"janus": "ack",
	"session_id": 7147844471131709
	"transaction": "43XefXDPTPMX"
}

• Janus網關–>>Janus客戶端: Janus網關返回webrtcup消息

{
	"janus": "webrtcup",
	"session_id": 7147844471131709,
	"sender": 7668325947218508
}

• Janus網關–>>Janus客戶端: Janus網關返回media（video）消息

{
	"janus": "media",
	"session_id": 7147844471131709,
	"sender": 7668325947218508,
	"type": "video",
	"receiving": true
}

• Janus網關–>>Janus客戶端: Janus網關返回media（audio）消息

{
	"janus": "media",
	"session_id": 7147844471131709,
	"sender": 7668325947218508,
	"type": "audio",
	"receiving": true
}

2.2 客戶端之間的交互

2.3 客戶端keepalive

• Janus客戶端->Janus網關: Janus客戶端發送keepalive

{
	"janus": "keepalive",
	"session_id": 7147844471131709,
	"transaction": "WZqW7GMauQpS"
}

• Janus網關–>>Janus客戶端: Janus網關返回ack消息

{
	"janus": "ack",
	"session_id": 7147844471131709,
	"transaction": "WZqW7GMauQpS"
}

3. 完整信令交互時序圖

4. 參考資料

基於Webrtc和Janus的多人視頻會議系統開發4 - 改造信令交互系統完成sdp交換過程
https://blog.csdn.net/u011382962/article/details/81708519