Add a sync collecting service for trace report.

language-agent/Tracing.proto

@@ -28,8 +28,18 @@ import "common/Common.proto";
 // Define a trace segment report service.
 // All language agents or any trace collecting component, could use this service to send span collection to the SkyWalking OAP backend.
 service TraceSegmentReportService {
+    // Recommended trace segment report channel.
+    // gRPC streaming provides better performance.
+    // All language agents should choose this.
     rpc collect (stream SegmentObject) returns (Commands) {
     }
+
+    // An alternative for trace report by using gRPC unary
+    // This is provided for some 3rd-party integration, if and only if they prefer the unary mode somehow.
+    // The performance of SkyWalking OAP server would be very similar with streaming report,
+    // the performance of the network and client side are affected
+    rpc collectInSync (SegmentCollection) returns (Commands) {
+    }
 }
 
 // The segment is a collection of spans. It includes all collected spans in a simple one request context, such as a HTTP request process.
@@ -203,4 +213,9 @@ enum SpanLayer {
     MQ = 4;
     // A cache layer, used in tracing the cache client component.
     Cache = 5;
+}
+
+// The segment collections for trace report in batch and sync mode.
+message SegmentCollection {
+    repeated SegmentObject segments = 1;
 }
\ No newline at end of file