Initial proposal of new api for go based gateway

pkg/apis/gateway.proto

@@ -0,0 +1,59 @@
+syntax="proto3";
+
+package api;
+
+// EndpointType defines supported endpoints' types
+enum EndpointType
+{
+    UNKNOWN = 0;
+    IPV4 = 1;
+    IPV6 = 2;
+    SID = 3;
+}
+
+// endpoint is expressed by it is type and the value of endpoint, whether it is address,
+// or SR SID is stored in byte array.
+message endpoint 
+{
+    EndpointType type = 1;
+    bytes address = 2;
+}
+// latency defines one of available QoE metrics
+// value expresses latency vallue in milliseconds.
+// variation expresses percent of the acceptable variation from value.
+message latency
+{
+    int32 value = 1;
+    int32 variation = 2;
+}
+// qoe_parameters defaines a list of QoE parameters a client can request.
+// Currently only latency is supported.
+message qoe_parameters
+{
+    latency latency = 1;
+}
+message qoe{
+    endpoint src = 1;
+    endpoint dst = 2;
+    qoe_parameters qoe = 3;
+    repeated uint32 label = 4;
+    int32 err = 5;
+}
+// RequestQoE defines the rpc message sent by the client to the gateway.
+// Multiple Src/Dst/QoE are supported in a single request.
+message RequestQoE
+{
+    map<int32, qoe>  qoes = 1;
+}
+// ResponseQoE defines  the rpc message sent as a reply to the client.
+// it is the same message as request, but the gateway populates labels and
+// err for each qoe.
+message ResponseQoE
+{
+    map<int32, qoe>  qoes = 1;
+}
+
+service QoEService
+{
+    rpc QoE (RequestQoE) returns (ResponseQoE);
+}