diff --git a/src/app/services/wsmessage.ts b/src/app/services/wsmessage.ts
index 22f20eb..1fceb3c 100644
--- a/src/app/services/wsmessage.ts
+++ b/src/app/services/wsmessage.ts
@@ -1,4 +1,5 @@
 export class WSMessage<T> {
   key: string;
+  trigger?: string;
   data: T;  // TODO: sane annotation
 }