Add CoAP observe

examples/scripts/coap-observe-client.js

@@ -0,0 +1,42 @@
+/********************************************************************************
+ * Copyright (c) 2018 Contributors to the Eclipse Foundation
+ * 
+ * See the NOTICE file(s) distributed with this work for additional
+ * information regarding copyright ownership.
+ * 
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0, or the W3C Software Notice and
+ * Document License (2015-05-13) which is available at
+ * https://www.w3.org/Consortium/Legal/2015/copyright-software-and-document.
+ * 
+ * SPDX-License-Identifier: EPL-2.0 OR W3C-20150513
+ ********************************************************************************/
+
+//Tested with https://github.com/mcollina/node-coap/blob/master/examples/observe_server.js
+
+let td = 
+`{
+    "name": "CoAP date server",
+    "id": "urn:dev:wot:coap:date",
+    "properties" : {
+        "mydate": {
+            "forms": [
+                {"href": "coap://localhost:5683"}
+            ]
+        }
+    }
+}`;
+
+let thing = WoT.consume(td);
+
+thing.properties.mydate.subscribe(
+	x => {
+		console.info("onNext: ", x);
+	},
+	e => console.log("onError: %s", e),
+	() => {
+		console.log("onCompleted");
+	}
+);
+console.info("Subscribed");

packages/binding-coap/src/coap-client.ts

@@ -134,8 +134,28 @@ export default class CoapClient implements ProtocolClient {
   }
 
   public subscribeResource(form: CoapForm, next: ((value: any) => void), error?: (error: any) => void, complete?: () => void): any {
-    error(new Error(`CoapClient does not implement subscribe`));
-    return null;
+    let req = this.generateRequest(form, "GET", true);
+
+    console.log(`CoapClient sending ${req.statusCode} to ${form.href}`);
+
+    req.on("response", (res: any) => {
+      console.log(`CoapClient received ${res.code} from ${form.href}`);
+      console.debug(`CoapClient received Content-Format: ${res.headers["Content-Format"]}`);
+
+      // FIXME does not work with blockwise because of node-coap
+      let contentType = res.headers["Content-Format"];
+      if (!contentType) contentType = form.contentType;
+
+      res.on('data', (data: any) => {
+        next({ type: contentType, body: res.payload });
+      });
+    });
+
+    req.on("error", (err: any) => error(err));
+
+    req.end();
+
+    return new Subscription( () => {} );
   }
 
   public start(): boolean {
@@ -166,7 +186,7 @@ export default class CoapClient implements ProtocolClient {
     return options;
   }
 
-  private generateRequest(form: CoapForm, dflt: string): any {
+  private generateRequest(form: CoapForm, dflt: string, observable: boolean = false): any {
 
     let options: CoapRequestConfig = this.uriToOptions(form.href);
 
@@ -182,6 +202,7 @@ export default class CoapClient implements ProtocolClient {
         default: console.warn("CoapClient got invalid 'methodCode', using default", options.method);
       }
     }
+    options.observe = observable;
 
     let req = this.agent.request(options);