DeviceWISE Angular API Service

Angular services for communicating with deviceWISE.

Installation

npm install devicewise-angular ngx-cookie-service fetch-readablestream --save

Import the devicewise angular module in your app.module.ts:

...
import { DevicewiseAngularModule } from 'devicewise-angular';

@NgModule({
  imports: [
    ...
    DevicewiseAngularModule.forRoot()

Then, import and inject the devicewise angular service into a component:

...
import { DevicewiseAuthService, DevicewiseApiService } from 'devicewise-angular';
import { switchMap } from 'rxjs/operators';

@Component({
  ...
})
export class AppComponent implements OnInit {
  constructor(
    private dwAuthentication: DevicewiseAuthService,
    private dwApi: DevicewiseApiService
  ) {}

  ngOnInit(): void {
    this.dwAuthentication.easyLogin('http://localhost:8080', 'admin', 'admin').pipe(
      switchMap((e) => this.dwApi.deviceList())
    ).subscribe((e) => console.log(e));
  }
  ...

The easyLogin method will automatically save the sessionId from the login request as a cookie. If a cookie already exists it will be checked for validity before emitting sucessful login.

MultiSubscribe

Using HTTP fetch is a much more efficient way to communicate with devicewise. Consider using the multisubscribe store service to subscribe to a variable rather than poll a variable on an interval.

...
import { DevicewiseAuthService } from 'devicewise-angular';

@Component({
  ...
})
export class AppComponent implements OnInit {
  constructor(
    private dwAuthentication: DevicewiseAuthService,
    private dwMultiSubscribeService: DevicewiseMultisubscribeStoreService
  ) { }

  variables: DwVariable[] = [{ device: 'System Monitor', variable: 'CPU.CPU Usage', type: DwType.UINT1, count: 1, length: -1 }];

  ngOnInit(): void {
    this.dwAuthentication.easyLogin('http://localhost:8080', 'admin', 'admin').pipe(
      switchMap((e) => this.dwMultiSubscribeService.addRequestVariables(this.variables))
    ).subscribe((e) => console.log('value changed:', e));
  }
  ...

Make sure you unsubscribe from the multisubscribe store obervable!

It's also common to save the observable.

this.multisub$ = this.dwMultiSubscribeService.subscriptionAsObservable();

To get a specific variable out of the observable create a pipe containing filter.

this.multisub$.pipe(
  filter((e) => e.device.name == 'System Monitor' && e.variable.name = 'CPU.CPU Usage')
).subscribe((e) => console.log(e))

Another possibility. Create an async pipe in your html template

<div *ngIf="multisub$ | async as variable">
  <p>Value: {{variable.data[0]}}</p>
</div>

This multisubscribe store makes it easy to add, remove, and edit variables from a single stream from devicewise.

Cross Origin Resource Sharing (CORS)

Cross-Origin Resource Sharing (CORS) is a mechanism that uses additional HTTP headers to tell browsers to give a web application running at one origin, access to selected resources from a different origin.

Run these steps to enable CORS on deviceWISE.

• Navigate to your deviceWISE install directory
• Open the file "deviceWISE\Runtime\dwcore\dwcore.properties"
• Add the line http.allow_origin=http://localhost:4200 anywhere in the file (where http://localhost:4200 is the origin to allow access. Use * for all origins.)
• Save the file
• Restart deviceWISE

Other deviceWISE HTTP Server Properties

Name	Description	Example
http.rootdirectory	Root directory of web server.
http.ssl.cert_file	Certificate to use for web server.
http.ssl.cert_pass	Certificate password, if necessary.
httpsvr.404.redirect	Redirect here instead of returning 404 error.	/index.html
http.allow_origin	CORS allowed origins. Comma separated or wildcard to allow all origins.	*
rewrite.source.#	Source to trigger rewrite	/.*\.html
rewrite.destination.#	Destination to write over source	/index.html
tryfiles.source.#	Source to trigger tryfiles	/.*
tryfiles.destination.#	Destination to write if file isn't found	/index.html

where # is a number 0-9

Polyfills

At the bottom of polyfills.ts under APPLICATION IMPORTS add the following and run the command in the comment.

/**
 * Fetch Readablestream Polyfills
 * https://github.com/jonnyreeves/fetch-readablestream
 * Run `npm install --save web-streams-polyfill text-encoding babel-polyfill whatwg-fetch abortcontroller-polyfill`.
 * This is used for subscriptions in IE11.
 */
import "web-streams-polyfill";
import "text-encoding";
import "babel-polyfill";
import "whatwg-fetch";
import "abortcontroller-polyfill";

I can't find a good polyfill for TextEncoder/Decoder. Add this CDN to your index.html.

<script src="https://cdn.jsdelivr.net/npm/text-encoding@0.6.4/lib/encoding.min.js"></script>

What to do now?

• Run ng test devicewise-angular to run the tests devicewise angular.
• Have a look at and play around with the app to get to know the devicewise service with ng serve --open
• Set up other users in deviceWISE (default credentials are admin/admin)

Running the Demo

Clone the repository.

git clone https://github.com/telit/devicewise-angular.git

Navigate to the folder.

cd devicewise-angular

Install packages.

npm i

Run Demo.

ng serve --open

FAQ

General tips

Checking out the following resources usually solves most of the problems people seem to have with this devicewise service:

• 📚 DeviceWISE Docs
• 📖 DeviceWISE Javascript Library
• 👩‍🚀 DeviceWISE Postman Collection

The following general steps are usually very helpful when debugging problems with this service:

• check out if there are any open or closed issues that answer your question
• ensure you have a valid sessionID cookie.
• explain to your local rubber duck why your code should work and why it (probably) does not

Opening issues

Please make sure to check out our FAQ before you open a new issue. Also, try to give us as much information as you can when you open an issue. Maybe you can even supply a test environment or test cases, if necessary?

Contributing

We are happy to accept pull requests or test cases for things that do not work. Feel free to submit one of those.

However, we will only accept pull requests that pass all tests and include some new ones (as long as it makes sense to add them, of course).

• Open a new pull request

Author

This library is provided to you free by Telit IoT Platforms.

License

MIT