Accessing the JS API via a web worker

[RobertHewlett]

I would like to offload some of the heavy lifting in a web app to a web worker.

It is a 2-3 second jank I would like gone.

Right now the web worker would still need access to parts of the API e.g. Extent and Polygon.

I have tried loading the init.js script via importScripts() but I still get errors.

Has anyone had any success with the ArcGIS JS-API inside a web worker ... not outside but inside. 

[RobertHewlett]

Hi Rene,

I am newbie on this part of the API so my conceptual thinking might be off but ....

Is proxy.connection.invoke basically the worker invoking one of its own methods/functions as this is usually done from the client side.

OR

Is the there a list of client side objects you can send into the worker and from within the worker call these methods/functions back in the client.

Rob

[ReneRubalcava]

It's not invoking a method on itself, the proxy.connection invoking a method on the object you are passing to workers.open(), that exist on the client. It can be anything you want, it just needs to have a method that returns a promise, because it's also a way for you to request information from the main thread from within the worker.

[RobertHewlett]

"You can then invoke any functions from the worker on this argument." 

What if the function updated the client UI? BOOM?

[RobertHewlett]

Just a heads up for others. Once I started using the proxy.connection as shown in the gist-sample the variable names on the client-side and the web-worker side had to match.

This might be a chrome-thing, transferable object-thing or a AJS-connection framework-thing. Not sure as I am a newbie to this part of the API.

If I do this on the non-web-worker side

 return connection.invoke("someFX", { argsAsJSON });‍

Then inside the web-worker I had to make the variable names match:

       Request.prototype.someFX = function someFX({argsAsJSON}, {proxy}) {‍

If I used another variable name then that variable would be undefined:

       Request.prototype.someFX = function someFX({data}, {proxy}) {‍

The line above (in the chrome debugger) would report data as undefined.

[RobertHewlett]

Can a FeatureSet be used inside a worker?

I am currently getting this error.

ErrorEvent {isTrusted: true, message: "Uncaught TypeError: Cannot read property 'compatMode' of null", filename: "http://js.arcgis.com/4.3/dojo/dojo.js", lineno: 168, colno: 316…}
bubbles
:
false
cancelBubble
:
false
cancelable
:
true
colno
:
316
composed
:
false
currentTarget
:
Worker
defaultPrevented
:
true
error
:
null
eventPhase
:
0
filename
:
"http://js.arcgis.com/4.3/dojo/dojo.js"
isTrusted
:
true
lineno
:
168
message
:
"Uncaught TypeError: Cannot read property 'compatMode' of null"
path
:
Array(0)
returnValue
:
false
srcElement
:
Worker
target
:
Worker
timeStamp
:
5463.285000000001
type
:
"error"
__proto__
:
ErrorEvent‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

[RobertHewlett]

Below is a copy of my define()

define([
    "esri/config",
    "esri/core/promiseUtils",
    "esri/geometry/geometryEngine",
    "esri/geometry/Extent",
    "esri/geometry/Polygon",
    "esri/tasks/support/FeatureSet"
], work);
‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

So far the worker works until I add:

    "esri/tasks/support/FeatureSet"
‍‍‍‍‍

[RobertHewlett]

Enjoy!

[RobertHewlett]

Updated video.

[MichalGasparovic]

Apologies for digging out this old thread. I'm running into the issue with the huge amount of requests and it's been recommended to do my own build. Let's assume I have it, how do I provided it to the worker?

https://community.esri.com/message/790617-re-web-worker-and-js-api-modules 

Thanks