Add message event size fields (#323)

Author: draffensperger

CHANGELOG.md

@@ -10,6 +10,7 @@ All notable changes to this project will be documented in this file.
 - Add support for supplying instrumentation configuration via tracing option. Option argument added to instrumentation interface.
 - Add ignoreIncomingPaths and ignoreOutgoingUrls support to the http and https tracing instrumentations.
 - Add ```opencensus-resource-util``` to auto detect AWS, GCE and Kubernetes(K8S) monitored resource, based on the environment where the application is running.
+- Add optional `uncompressedSize` and `compressedSize` fields to `MessageEvent` interface.
 
  **This release has multiple breaking changes. Please test your code accordingly after upgrading.**
 

packages/opencensus-core/src/trace/model/types.ts

@@ -48,6 +48,13 @@ export interface MessageEvent {
   type: string;
   /** An identifier for the MessageEvent's message. */
   id: string;
+  /** The number of uncompressed bytes sent or received. */
+  uncompressedSize?: number;
+  /**
+   * The number of compressed bytes sent or received. If zero or
+   * undefined, assumed to be the same size as uncompressed.
+   */
+  compressedSize?: number;
 }
 
 /**