Core Concepts

The Glue42 Angular wrapper, @glue42/ng, provides you with an easy way to initialize the Glue42 JavaScript libraries and use Glue42 functionalities in your projects. It works with the @glue42/web and @glue42/web-platform libraries, if you are working on a Glue42 Core project, and with the @glue42/desktop library, if you are working on a Glue42 Enterprise project. The examples below use the Glue42 Web library.

This package should be used only in Angular apps. If you created your app with the Angular CLI, then you don't need to take any additional steps. Otherwise, make sure to install the peer dependencies of @glue42/ng:

"dependencies": {
    "@angular/common": "^9.1.3",
    "@angular/core": "^9.1.3",
    "rxjs": "^6.5.5",
    "tslib": "^1.10.0"
}

Note that @glue42/ng supports Angular 7+.

The example below assumes that your app was created with the Angular CLI. Install @glue42/ng and the Glue42 Web library:

npm install --save @glue42/ng @glue42/web

The Glue42 Angular library exposes two important elements:

• Glue42Ng - an Angular module that initializes the Glue42 Web library;
• Glue42Store - an Angular service that gives access to the Glue42 Web APIs;

Glue42Ng Module

The Glue42Ng module is responsible for initializing the Glue42 Web library. You must import the Glue42Ng module once for the entire app - in the root module by using the forRoot() method. This methods accepts a settings object which has the following signature:

export interface Glue42NgSettings {
    holdInit?: boolean;
    web?: {
        factory?: Glue42WebFactoryFunction;
        config?: Glue42Web.Config;
    };
    webPlatform?: {
        factory?: Glue42WebPlatformFactoryFunction;
        config?: Glue42WebPlatform.Config;
    };
    desktop?: {
        factory?: Glue42DesktopFactoryFunction;
        config?: Glue42.Config;
    };
}

The table below describes the properties of the Glue42NgSettings object.

Note that you can't define a web and webPlatform property at the same time, but you can define one of them together with desktop. This is useful if you want your app to have different initialization characteristics in Glue42 Core and Glue42 Enterprise.

All properties are optional, but it is recommended that you provide the factory functions explicitly. If no factory functions are provided, the library will try to select an appropriate function attached to the global window object.

The initialization of the Glue42 Web library is asynchronous and therefore may take anywhere from a few milliseconds to a couple of seconds. There are two main situations in which setting holdInit to true (default) or false will benefit your project:

• holdInit: false - If the Glue42 functionalities play only a supporting role in your project, rather than being an essential part of it, it is recommended that you set holdInit to false. This way, your app won't have to wait for the Glue42 library to initialize in order to be able to function properly. You can use the Glue42Store service to get notified when the Glue42 Web library is ready.

• holdInit: true - If the Glue42 functionalities are a critical part your project, then it is recommended to leave holdInit set to true. This way, Angular will wait for the Glue42 factory function to resolve before bootstrapping your first component. This will spare you the need to check whether the Glue42 Web library is available or not every time you want to use it in your app. As a negative result to this approach, when your users load the app, they will keep seeing a blank screen up until the first component has been bootstrapped. Of course, you can solve this by providing a loader animation as soon as your app is accessed.

The example below shows how to initialize the Glue42 Web library by passing a factory function and a custom configuration object:

import { Glue42Ng } from "@glue42/ng";
import GlueWeb from "@glue42/web";

@NgModule({
    declarations: [
        AppComponent
    ],
    imports: [
        BrowserModule,
        Glue42Ng.forRoot({ web: { factory: GlueWeb } })
    ],
    providers: [],
    bootstrap: [AppComponent]
})
export class AppModule { }

It is important to note that if the Glue42 initialization fails for any reason (invalid configuration, missing factory function, connection problems or initialization timeout), your app will still initialize.

Glue42Store Service

The Glue42Store service is used to obtain the glue object which exposes the Glue42 Web API. This service can also notify you when the Glue42 Web library has been initialized and enables you to check for any initialization errors.

Example of creating a Glue42Store service:

import { Injectable } from "@angular/core";
import { Glue42Store } from "@glue42/ng";

@Injectable()
export class Glue42Service {
    constructor(private readonly glueStore: Glue42Store) { }
}

The Glue42Store service offers the following methods:

You can now inject the service in the components that need it and access the Glue42 Web API from the object returned by this.glueStore.getGlue(). This gives you a decent level of encapsulation and control. If you prefer handling async actions with Observables, then this service is the perfect place to wrap the methods you want to use in Observables.

The following examples demonstrate initializing and using the Glue42 Angular library.

Initialization

Import the Glue42Ng module in the root module of your app and pass a Glue42 factory function:

import { BrowserModule } from "@angular/platform-browser";
import { NgModule } from "@angular/core";

import { AppComponent } from "./app.component";
import { Glue42Ng } from "@glue42/ng";
import GlueWeb from "@glue42/web";

@NgModule({
    declarations: [
        AppComponent
    ],
    imports: [
        BrowserModule,
        Glue42Ng.forRoot({ web: { factory: GlueWeb } })
    ],
    providers: [],
    bootstrap: [AppComponent]
})
export class AppModule { }

Consuming Glue42 Web APIs

Inject the Glue42Store service in your component/service of choice in order to use the Glue42 Web API. It is recommended that you create your own Angular service that injects the Glue42Store and exposes only the functionality your app needs.

When initializing the Glue42 Web library with the Glue42Ng module, you can use the holdInit property (see Glue42Ng Module) to configure whether the Angular framework must wait for the Glue42 factory function to resolve before bootstrapping your first component. Depending on this setting, you can use the Glue42Store service in different ways. Below are given examples and short explanations for both cases:

• holdInit: true

Creating the service:

import { Injectable } from "@angular/core";
import { Glue42Store } from "@glue42/ng";

@Injectable()
export class Glue42Service {

    constructor(private readonly glueStore: Glue42Store) { }

    public get glueAvailable() {
        return !this.glueStore.getInitError();
    }

    public registerMethod(name: string, callback: () => void): Promise<void> {
        if (!this.glueAvailable) {
            return Promise.reject("Glue42 was not initialized.");
        }
        return this.glueStore.getGlue().interop.register(name, callback);
    }
}

Using the service:

import { Component, OnInit } from "@angular/core";
import { Glue42Service } from "./my-glue-service";

@Component({
    selector: "app-root",
    templateUrl: "./app.component.html",
    styleUrls: ["./app.component.css"]
})
export class AppComponent implements OnInit {

    constructor(private glueService: Glue42Service) { }

    public ngOnInit(): void {
        if (!this.glueService.glueAvailable) {
            // Тhere has been an error during the Glue42 initialization.
            return;
        }
        // Glue42 has been initialized without errors and is ready to use.
    }
}

If you set holdInit to true (default), you can be sure that everywhere you inject the Glue42Store service, the respective properties will be initialized and set. This is very convenient, because you don't have to subscribe and wait for an event in order to use the Glue42 Web library. However, you do need to always check if there is an initialization error by using this.glueStore.getInitError(). If the Glue42 factory function throws an error, your app won't crash, but Glue42 won't be available and the value returned by getInitError() will be set to the respective error object during initialization.

• holdInit: false

Creating the service:

import { Injectable } from "@angular/core";
import { Glue42Store } from "@glue42/ng";

@Injectable()
export class Glue42Service {

    constructor(private readonly glueStore: Glue42Store) { }

    public ready() {
        return this.glueStore.ready;
    }

    public registerMethod(name: string, callback: () => void): Promise<void> {
        return this.glueStore.getGlue().interop.register(name, callback);
    }
}

Using the service:

import { Component, OnInit } from "@angular/core";
import { Glue42Service } from "./my-glue-service";

@Component({
    selector: "app-root",
    templateUrl: "./app.component.html",
    styleUrls: ["./app.component.css"]
})
export class AppComponent implements OnInit {

    constructor(private glueService: Glue42Service) { }

    public ngOnInit(): void {
        // Show the loader.
        this.glueService
            .ready()
            .subscribe((glueStatus) => {
                if (glueStatus.error) {
                    // Hide the loader.
                    // Glue42 isn't available.
                    return;
                }
                // Hide the loader.
                // Glue42 is ready, continue with your logic.
            })
    }
}

As you can see, this approach requires a little bit more code, but it gives you an easy way to provide pleasant user experience while Glue42 is initializing, handle gracefully any initialization errors, and when the initialization resolves normally, you don't need to check the error object as in the previous example.