Object.observe is obsolete with ES6. Try to find a solution with Proxy

[franckOL]

Object.observe(resources.links.actions.resources[actionId].data, function (changes) {
       ^

TypeError: Object.observe is not a function
at C:_Utilisateur\Project\ObjectIn\webofthings.js\plugins\corePlugin.js:70:
12
at arrayEach (C:_Utilisateur\Project\ObjectIn\webofthings.js\node_modules\l
odash\internal\arrayEach.js:15:9)
at Object. (C:Utilisateur\Project\ObjectIn\webofthings.js\node
modules\lodash\internal\createForEach.js:15:9)
at CorePlugin.observeActions (C:_Utilisateur\Project\ObjectIn\webofthings.j
s\plugins\corePlugin.js:69:5)
at CorePlugin.start (C:_Utilisateur\Project\ObjectIn\webofthings.js\plugins
\corePlugin.js:30:26)
at initPlugins (C:_Utilisateur\Project\ObjectIn\webofthings.js\wot-server.j
s:50:14)
at createServer (C:_Utilisateur\Project\ObjectIn\webofthings.js\wot-server.
js:12:3)
at Object. (C:_Utilisateur\Project\ObjectIn\webofthings.js\wot.j
s:2:1)
at Module._compile (module.js:541:32)
at Object.Module._extensions..js (module.js:550:10)
at Module.load (module.js:458:32)
at tryModuleLoad (module.js:417:12)
at Function.Module._load (module.js:409:3)
at Module.runMain (module.js:575:10)
at run (node.js:348:7)
at startup (node.js:140:9)

[franckOL]

Found that https://github.com/anywhichway/proxy-observe , but seem too heavy

[domguinard]

Thanks franckOL. We actually did see that this was deprecated and started experimenting with alternatives. Will report on our findings and hopefully provide a patch soon. For now, the ideal is to stick with the current Node LTS: 4.X which still supports Object.observe().

[franckOL]

Hi,
What about the pull request, it works for all version of node js, and it's really minor change.
Franck

[domguinard]

Sorry about that Franck, we missed the PR. This is really simple and great. I just accepted the PR, thanks a lot!

[domguinard]

Reopening as the new Node LTS is now 6 we'll be looking into this.

[ngmgithub]

Running the latest commit in master as of today. Still seeing the Object.observe is not a function issue.

webofthings/wot-book@9ab17ed

Running Node v6.10.0 over nvm

[developer-tarun]

Hi Guys ! Any solution to this problem ? I am going through chapter 7 of webofthings, and I am stuck because of this Object.observe problem when i try to execute the wot.js

[domguinard]

Hi guys, we have tested a number of solutions but haven't found a totally nice and simple one yet, we are still working on it but meanwhile I would stick to Node 4.X which supports Object.observe(). (you can install several version of node with NVM)

[logivity]

Any update on this?

[ngmgithub]

Maybe we should work on some suggestions in the community to get them started. The following may be a useful tutorial to get started. https://www.bitovi.com/blog/long-live-es6-proxies

…

On Sat, Jul 1, 2017 at 3:12 PM, logivity ***@***.***> wrote: Any update on this? — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#3 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ACxalq47R2T3BTiH2RWKw5cQDOMlLpW7ks5sJfFVgaJpZM4Je5gQ> .

[domguinard]

Thanks for the ping and sorry for being so incredibly slow on that one. We had a fix (see PR) but there were a few weird behaviours. I'll get back to it asap but feel free to help. I'll start with a look at the link thanks for that.

[franckOL]

Hello, @domguinard, i see some evolution on W3C draft on WOT specification, also what is your advice . may be we can use ==> https://github.com/thingweb/node-wot ?

[ngmgithub]

@domguinard We had some previous discussion about the use of ES6 proxies. Another alternative would be the use of event emitters of which I am attempting to become more familiar. Any thoughts on this approach?

[germain171]

Hi all, very new to this dev stuff. so dont mind my silly question.
i get this, when 'possibly' using the newest version of Chrome to debug a Mobile device. which i think is on an older version of chrome wrapped in an Industrial Browser.
Uncaught TypeError: Object.observe is not a function at WebInspector.Main._createSettings (inspector.js:10452) at WebInspector.Main._gotPreferences (inspector.js:10444) at DevToolsAPIImpl.embedderMessageAck (devtools_compatibility.js:33) at <anonymous>:1:13
When using command navigator.appVersion.match(/.*Chrome\/([0-9\.]+)/)[1] in the dev console with the remote browser connected, i get the dev console version of 72.0.3626.109.
so at this point i cannot even interrogate what the version of chrome/ind browser. To see if it is a version compatibility issue.
My current plan, and its not a great one. Is to download and install Chrome from a random guess age in the past and keep downloading older ones until it works. ( i dont like this fix)

Just tried it in straight Chrome with out ind Browser wrapper. still the same. so it not the Ind Browser part that is an issue. and i cannot update the Browser on the Device. (Lollipop)

Any ideas ?

[aolite]

Hi all, thank you very much for the ideas exposed here. I personally have tries to implement the examples of chapter 7 using nest.js as a server. During the implementation, we also found the deprecated method Object.observer().

To overcome this problem, I created a proxy variable to watch for changes in the object. Inside the proxy, I created an event emitter to send an event to the socket connection to perform the send operation to the WebSocket client:

const myEvent = new EventEmitter();
const proxyResource = new Proxy(resourcesJson, {
    get: function(target, prop) {
      console.log({ type: 'get', target, prop });
      myEvent.emit('ws-wot');
      return Reflect.get(target, prop);
    },
    set: function(target, prop, value) {
      console.log({ type: 'set', target, prop, value });
      
      return Reflect.set(target, prop, value);
    }
  });

One more change to be performed is on the plugins that require to change the proxy variable directly in order to reflect the change over the object:

private simulate(): void {
        this.interval = setInterval(() => {
            proxyResource.pi.sensors.pir.value = !this.model.value;
            this.showValue();
        }, this.localParams.frequency);
        this.logger.log(`Simulated sensor ${this.pluginName} sensor Started!`);
    }

Last step os to establish the WebSocket gateway is formed by a function in charge of accepting connections. Once the WS client connected is able to get data streams from the server once the data is generated.

@WebSocketGateway( { transports: ['websocket'] })
export class EventsGateway /*implements OnGatewayConnection, OnGatewayDisconnect*/{

  @WebSocketServer() server: Server;
  private logger = new Logger(EventsGateway.name);

  handleConnection(client: any, ...args: any[]) {
    this.logger.log(`New Connection:${args [0]}`);
    //this.logger.log(inspect(client))
    this.logger.log(inspect(args[0].url))
    const url = args[0].url;
    this.logger.log(inspect(url));

    client.send('Listening data...');

    myEvent.on('ws-wot', ()=>{
      this.logger.log('Event acquired');
      client.send(JSON.stringify(this.selectedResource(url)));
    });
    
  }
...

For your consideration, the complete example is here

[DavidGomez-dev]

Hi there,
Maybe not the best solution, but some idea for a simple one.
I used the own resources.json as a simple database.
In the plugin I used readFile and a setInterval to check the value with some frequency.
Then on the actuator router, I used readFile and writeFile to update the value on the json according to the PUT value of the call.
Just another idea.