feat: notifiers support in aries rest client js worker

- new constructor opts `agent-rest-wshook` in rest client based aries js
worker. If provided then `aries.startNotifier` can be used to listen to
incoming messages

- closes hyperledger-archives#1370

Signed-off-by: sudesh.shetty <sudesh.shetty@securekey.com>

cmd/aries-js-worker/README.md

@@ -113,7 +113,8 @@ Then initialize your aries instance:
 ```js
 const aries = await new Aries.Framework({
     assetsPath: "/path/serving/the/assets", // still required for assets other than the wasm
-    "agent-rest-url": "http://controller.api.example.com"
+    "agent-rest-url": "http://controller.api.example.com", // REST controller URL of the agent
+    "agent-rest-wshook": "ws://controller.api.example.com" // Optional REST controller websocket URL from which you can listen to notifications
 })
 ```
 

cmd/aries-js-worker/index.html

@@ -106,7 +106,7 @@
             document.getElementById("mode-label").innerHTML = `Running in ${mode} mode`
 
             if (src == "rest"){
-                document.getElementById("opts").innerHTML = `{"assetsPath": "/dist/assets", "agent-rest-url": "http://localhost:8082"}`
+                document.getElementById("opts").innerHTML = `{"assetsPath": "/dist/assets", "agent-rest-url": "http://localhost:8082", "agent-rest-wshook":"ws://localhost:8881"}`
             } else {
                 document.getElementById("opts").innerHTML = `{"assetsPath": "/dist/assets", "agent-default-label":"dem-js-agent","http-resolver-url":[],"auto-accept":true,"outbound-transport":["ws","http"],"transport-return-route":"all","log-level":"debug"}`
             }

cmd/aries-js-worker/src/aries.js

@@ -91,7 +91,8 @@ function newMsg(pkg, fn, payload) {
  *      "outbound-transport": ["ws", "http"],
  *      "transport-return-route": "all",
  *      "log-level": "debug",
- *      "agent-rest-url": "http://controller.api.example.com"
+ *      "agent-rest-url": "http://controller.api.example.com",
+ *      "agent-rest-wshook": "ws://controller.api.example.com"
  * }
  *
  * @param opts framework initialization options.

cmd/aries-js-worker/src/worker-impl-rest.js

@@ -9,7 +9,9 @@ self.importScripts("./agent-rest-client.js")
 postMessage({topic: "asset-ready"})
 
 // TODO synchronized access to controller
-let handler, controller
+let handler, controller, notifier
+
+const wsNormalClosureCode = 1000
 
 const ariesHandle = {
     aries: {
@@ -22,6 +24,13 @@ const ariesHandle = {
                 return newResponse(data.id, null, "'agent-rest-url' is required");
             }
 
+            if (data.payload["agent-rest-wshook"]){
+                notifier = new wsnotifier(data.payload["agent-rest-wshook"], (msg) => {
+                    postMessage(msg)
+                });
+            }
+
+
             controller = new RESTAgent.Client(data.payload["agent-rest-url"], data.payload["agent-rest-token"]);
             return newResponse(data.id, "aries is started");
         },
@@ -67,4 +76,18 @@ function newResponse(id, payload, errMsg, topic) {
         errMsg: errMsg,
         topic: topic
     };
-}
+}
+
+const wsnotifier = class {
+    constructor(url, postMsg) {
+        this.socket = new WebSocket(url);
+        this.socket.addEventListener('message', function (event) {
+            // TODO REST agents are not currently revealing topic information on incoming messages,
+            //  Once REST supports this feature, topic value will be dynamic. [Issue #1323]
+            postMsg(newResponse(Math.random().toString(36).slice(2),  event.data, "", "all"));
+        });
+    }
+    stop(){
+        this.socket.close(wsNormalClosureCode, "stopped notifier in aries-js-worker")
+    }
+};