Add document for stream service

doc/design/stream-service.md

@@ -0,0 +1,138 @@
+# Stream service
+
+## Overview
+Stream service provides functionality to control streams and subscriptions directly in OWT server. Related REST interfaces are added in management API.
+
+## Architecture and dataflow
+
+![data flow](./pics/)
+
+
+## REST API
+
+The following REST APIs can be called in the same way as management REST APIs (). The url prefix for stream service is "/cluster/".
+
+### Publication
+A publication represents the stream published by user. 
+
+Data format of publication:
+
+    {
+        "id": "publicationId(string)",
+        "type": "webrtc|streaming|...",
+        "source": {
+            "audio": [
+                {"id": "trackId", "format": {/*Audio format*/}, "info": {/*info*/}}
+            ],
+            "video": [
+                {
+                    "id": "trackId",
+                    "format": {/*Video format*/},
+                    "parameters": {/*Video parameters*/},
+                    "info": {/*Track info*/}
+                }
+            ],
+            "data": [
+                {"id": "trackId"}
+            ]
+        },
+        "info": {
+            "owner": "participantId for WebRTC streams",
+            "attributes": "customized attributes"   
+        },
+        "locality": {"node": "actual node", "agent": "node manager"},
+        "domain": "string used to describe scope like room"
+    }
+
+POST hostname:port/v1.1/cluster/publications - publish
+GET hostname:port/v1.1/cluster/publications - list publications
+GET hostname:port/v1.1/cluster/publications/:pubId - get publication info with given ID
+DELETE hostname:port/v1.1/cluster/publications/:pubId - unpublish
+
+
+### Subscription
+A subscription represents stream subscribed by user.
+
+Data format of subscription:
+
+    {
+        "id": "subscriptionId(string)",
+        "type": "webrtc|streaming|recording|...",
+        "sink": {
+            "audio": [
+                {
+                    "id": "trackId",
+                    "from": "fromSourceId",
+                    "format": {/*Audio format*/},
+                    "info": {/*info*/}
+                }
+            ],
+            "video": [
+                {
+                    "id": "trackId",
+                    "from": "fromSourceId",
+                    "format": {/*Video format*/},
+                    "parameters": {/*Video parameters*/},
+                    "info": {/*Track info*/}
+                }
+            ],
+            "data": [
+                {"id": "trackId", "from": "fromSourceId"}
+            ]
+        },
+        "info": {
+            "owner": "participantId for WebRTC streams",
+            "attributes": "customized attributes"   
+        },
+        "locality": {"node": "actual node", "agent": "node manager"},
+        "domain": "string used to describe scope like room"
+    }
+
+POST hostname:port/v1.1/cluster/subscriptions - subscribe
+GET hostname:port/v1.1/cluster/subscriptions - list subscriptions
+GET hostname:port/v1.1/cluster/subscriptions/:subId - get subscription info with given ID
+DELETE hostname:port/v1.1/cluster/subscriptions/:subId - unsubscribe
+
+### Processor
+A processor takes streams as input and produces new streams as output, such as mixer and transcoder.
+
+Data format of processor:
+
+    {
+        "id": "processorId(string)",
+        "type": "vmixer|vtranscoder|...",
+        "inputs": {
+            "audio": [
+                {"id": "inputId", "from": "fromSourceId"}
+            ],
+            video: [],
+            data: [],
+        },
+        outputs: {
+            audio: [
+                {"id": "outputId", "info": "outputInfo"}
+            ],
+            video: [],
+            data: [],
+        },
+        info: {
+
+        },
+        "locality": {"node": "actual node", "agent": "node manager"},
+        "domain": "string used to describe scope like room"
+    }
+
+### Node
+A node represents a working process of specific type in the cluster.
+
+Data format of node:
+
+    {
+        "id": "nodeID",
+        "agent": "ID of its manager agent",
+        "type": "webrtc|...",
+        "pubs": ["list of publication IDs on this node"],
+        "subs": ["list of subscription IDs on this node"]
+    }
+
+GET hostname:port/v1.1/cluster/nodes - list nodes