Syshub Rest Module

The syshub-rest-module was developed to simplify communication between an Angular single-page application (SPA) and an NT-Ware uniFLOW sysHUB server. It provides easy access to the REST interface of the sysHUB server, supporting OAuth2, Basic, and API Key authentication mechanisms.

The module consists of four main components, of which the RestService is the class with which the SPA interacts the most. The service provides methods for login to and logout from the server, as well as methods for communicating with the Rest API. Inconspicuous further components are the Settings class, which validates the configuration provided by the SPA; the Session class, which takes care of storing and renewing the OAuth tokens; the Interceptor, which adds the correct and required HTTP headers to a request depending on the selected authentication and the data sent to the server.

The following sections describe the initial installation in an Angular app, the use of the login and logout functionality and the call of the Rest API methods.

Install

To add the syshub-rest-module to your project as a dependency, execute the following command in the root directory of your Angular 17 project:

npm i syshub-rest-module

For projects using older versions of Angular, please refer to the table below to find the appropriate version of the syshub-rest-module and the corresponding installation command.

Angular version	Syshub Rest Module version	install cmd
17.x	5.x (4.x to 3.x)	npm i syshub-rest-module@^5
16.x	2.x	npm i syshub-rest-module@^2

Configuration

After installing the module, you need to set up your credentials. This is typically done in your environment.ts file. If you don't have an environment.ts file yet, refer to this StackOverflow article for guidance.

Ensure that your configuration includes at least one element that implements either the BasicRestSettings or OAuthRestSettings type. These types specify the requirements for establishing a connection to a sysHUB Server.

Type hints (comments) are provided for each type and property, serving as documentation. You can also find these comments in the source code.

Example configuration - Basic auth (static)

The following code is an example to set up your environment for basic authentication. This example uses static, predefined user-independent access data. In the scenario where the access data is entered by a user, please use the following section.

import { BasicRestSettings } from "syshub-rest-module";

export type MyEnvironment = {
    syshub: BasicRestSettings
}

export const environment: MyEnvironment = {
    syshub: {
        host: "/",
        basic: {
            enabled: true,
            username: "<basic username>",
            password: "<basic password>",
            provider: "<basic api provider>",
        },
        throwErrors: false
    }
};

Example configuration - Basic auth (user input)

The following code is an example of how to set up your environment for basic authentication where the access data (username and password) comes through the web application, e.g. through a user input. In this case, a login must be executed before the first request to the Rest API. The access data is then saved in the browser cache.

import { BasicRestSettings } from "syshub-rest-module";

export type MyEnvironment = {
    syshub: BasicRestSettings
}

export const environment: MyEnvironment = {
    syshub: {
        host: "/",
        basic: {
            enabled: true,
            requiresLogin: true,
            username: "",
            password: "",
            provider: "<basic api provider>",
        },
        throwErrors: false
    }
};

Example configuration - OAuth

The following code is an example of how to set up your environment for OAuth2 authentication. In order for an endpoint of the Rest API to be retrieved, a login must first take place or a valid session must exist in the browser. See the following sections User login example and Check login state before sending request.

import { OAuthRestSettings } from "syshub-rest-module";

export type MyEnvironment = {
    syshub: OAuthRestSettings
}

export const environment: MyEnvironment = {
    syshub: {
        host: "/",
        oauth: {
            enabled: true,
            clientId: "<oauth client id>",
            clientSecret: "<oauth client secret>",
            scope: "public"
        },
        throwErrors: false
    }
};

Example configuration - API key

With the following configuration, it is possible to use the API keys from version 2024 of the sysHUB Server. In this case, no login is possible or permitted and calls to the Rest API only allow the public scope (according to the sysHUB documentation).

import { ApikeyRestSettings, SyshubVersion } from "syshub-rest-module";

export type MyEnvironment = {
    syshub: ApikeyRestSettings
}

export const environment: MyEnvironment = {
    syshub: {
        host: "/",
        apiKey: "<your api key here>",
        provider: "<your auth provider name here>",
        scope: "public",
        version: SyshubVersion.sysHUB_2024,
        throwErrors: false
    }
};

Server Versions

The REST API of sysHUB has undergone significant changes from version 2021 to 2022, and minor updates from 2022 to 2023. It is now accessible via /webapi/ instead of the previous /cosmos-webapi/. Consequently, this module introduces a version switch in its configuration to accommodate these changes. If this switch is not explicitly set, the module defaults to the latest version, which is currently 2023. To configure the module for use with sysHUB server versions 2021 or 2022, adjust the version setting as necessary.

Below is a code example demonstrating how to configure the REST module for a sysHUB server version 2023:

import { BasicRestSettings, SyshubVersion } from "syshub-rest-module";

export type MyEnvironment = {
    syshub: BasicRestSettings
}

export const environment: MyEnvironment = {
    syshub: {
        host: "/",
        version: SyshubVersion.sysHUB_2023,
        basic: {
            enabled: true,
            username: "<basic username>",
            password: "<basic password>",
            provider: "<basic api provider>",
        },
        throwErrors: false
    }
};

Link module in your app.module.ts

In your app.module.ts make sure that the HttpClientModule is imported and add the three providers Settings, RestService and HTTP_INTERCEPTORS. The minimal configuration looks something like this:

import { HTTP_INTERCEPTORS, HttpClient, HttpClientModule } from '@angular/common/http';
import { NgModule } from '@angular/core';
import { RestService, RestSettings, Settings, SyshubInterceptor } from 'syshub-rest-module';

@NgModule({
  imports: [
    HttpClientModule,
  ],
  providers: [
    { provide: Settings, multi: false, useValue: new Settings(<RestSettings>(environment.syshub)) },
    { provide: RestService, multi: false, deps: [Settings, HttpClient] },
    { provide: HTTP_INTERCEPTORS, multi: true, useClass: SyshubInterceptor, deps: [Settings, RestService] },
  ],
})
export class AppModule { }

The Settings provider requires an initialised object of the class Settings, whose constructor in turn expects an object corresponding to the type RestSettings. For an example, see object environment.syshub in the Install/Setup configuration chapter.

Usage

In each component that needs access to the sysHUB Rest API, the RestService must be imported and injected in the constructor of the component. Minimal example:

import { RestService } from 'syshub-rest-module';

@Component({})
export class FooComponent {
  constructor(private restService: RestService) {}
}

Userlogin example

The user login is programmed with a few lines of code. In the following example, the onSubmitBtnClicked() method is called by clicking a button in the HTML and the contents of the variables username and password are sent to the sysHUB server via the login() method of the RestService. The response is then either true in case of success or an error containing further information. In case of success, the Rest Service saves the received token and takes care of its renewal.

import { Component } from '@angular/core';
import { RestService } from 'syshub-rest-module';

@Component({
  selector: 'app-login-min',
  templateUrl: './login-min.component.html',
  styleUrls: ['./login-min.component.scss']
})
export class LoginMinComponent {

  username: string = 'foo';
  password: string = '<foobar!>';

  constructor(private restService: RestService) { }

  onSubmitBtnClicked(): void {
    this.restService.login(this.username, this.password).subscribe((response) => {
      if (response === null) // Initial status, not yet any response from server
        return;
      if (response === true) // Login successfull
        console.log(`User ${this.username} logged in`);
      else // Error while logging in, see details in response
        console.log(response);
    });
  }

}

Temporary sessions

In this example, temporary sessions are utilized to store user login data. By setting the third parameter of the login() method to false, the user credentials are stored in the sessionStorage instead of the localStorage of the browser.

  this.restService.login(this.username, this.password, false).subscribe((response) => { 
    // your code goes here
  });

Sessions stored in the sessionStorage are automatically cleared when the browser is closed, providing a secure and temporary means of storing user authentication data.

Check login state before sending request

Before sending a request to the server's Rest API, it should be ensured that a user is logged in. For this, either the method getIsLoggedIn() of the RestService can be queried or subscribed to isLoggedIn. isLoggedIn reports every change of the login status and so it is also possible to react on successful logout and login.

In the following example code (which supplements the code from the previous section Userlogin example), the properties loggedIn and sub have been added. In the constructor, RestService.isLoggedIn is subscribed to and any status change is stored in loggedIn. The subscription itself is stored in sub and terminated when the component is exited.

import { Component, OnDestroy } from '@angular/core';
import { Subscription } from 'rxjs';
import { RestService } from 'syshub-rest-module';

@Component({
  selector: 'app-login-min',
  templateUrl: './login-min.component.html',
  styleUrls: ['./login-min.component.scss']
})
export class LoginMinComponent implements OnDestroy {

  username: string = 'foo';
  password: string = '<foobar!>';

  loggedIn: boolean = false;
  sub?: Subscription;

  constructor(private restService: RestService) {
    this.sub = this.restService.isLoggedIn.subscribe((state) => this.loggedIn = state);
  }

  ngOnDestroy(): void {
    this.sub?.unsubscribe();
  }

  onSubmitBtnClicked(): void {
    this.restService.login(this.username, this.password).subscribe((response) => {
      if (response === null) // Initial status, not yet any response from server
        return;
      if (response === true) // Login successfull
        console.log(`User ${this.username} logged in`);
      else // Error while logging in, see details in response
        console.log(response);
    });
  }

}

Renewal of OAuth2 tokens

There may be a short period of half a second or less where requests are deferred to the Rest API to refresh the token and store it in the browser cache. The calling function will not notice this as the subscription will not be updated while waiting for the renewal method to complete. This happens automatically and is not configurable.

If the module did not defer the requests, it can happen that a request uses an old access token that has already been changed in the backend but has not yet been updated in the browser. This then leads to a 403/Forbidden status.

Calling Rest API endpoints

Calling Rest API endpoints is quite simple with the RestService. Call one of the generic methods get(), post(), delete(), patch() or put() of the RestService to reach any endpoint. For post(), patch() and put() a payload is required in addition to the endpoint. The content of the payload can be seen in the Swagger definition. Important: The actual call to the sysHUB server only takes place when the result is subscribed to, nothing happens before that.

HTTP GET

this.restService.get('currentUser', undefined, true).subscribe((response) => {
  if (response.status == HttpStatusCode.Ok) {
    // Ok response
    /**
     * The sysHUB server may return a status code other than 200/OK.
     * The specification for this can be found in Swagger.
     */
  } else {
    //Failed response 
  }
});

HTTP POST

this.restService.post('jobs', {...}).subscribe((response) => {
  if (response.status == HttpStatusCode.Ok) {
    // Ok response
    /**
     * The sysHUB server may return a status code other than 200/OK.
     * The specification for this can be found in Swagger.
     */
  } else {
    //Failed response 
  }
});

Upload files

To upload files to a sysHUB server, the ContentType must be set as multipart/form-data. This is done automatically by the RestService if the object to be sent is of the type FormData. The following example shows the upload of a file as a ticket file for an existing sysHUB job:

onUploadFile(jobid: number, file: File, filename: string) {
  let formdata = new FormData();
  formdata.append('filename', filename);
  formdata.append('file', file, filename); 
  const urlpart = `jobs/${jobid}/uploadFile?type=ticket`; 
  this.restService.post(urlpart, formdata).subscribe((response) => {
    if (response.status == HttpStatusCode.Created) {
      // Ok response
      /**
       * The sysHUB server may return a status code other than 200/OK.
       * The specification for this can be found in Swagger.
       */
    } else {
      //Failed response 
    }
  });
}

HTTP DELETE, PATCH and PUT

The sysHUB Rest API also expects the HTTP methods Delete, Head, Patch or Put depending on the endpoint. Accordingly, the RestService also provides these methods. Since they work almost identically to the get() and post() methods, there are no separate instructions for their use here. Just replace RestService.get() with RestService.delete() to call a delete endpoint. Replace RestService.post() with RestService.patch() or RestService.put() to call the patch and put endpoints. The latter also expect an object to be sent to the web server.

HTTP HEAD, OPTIONS

To use the head or options HTTP methods, simply call those RestService methods: RestService.head(), RestService.options().

Custom endpoints

Since version 2023, the sysHUB server supports custom Rest API endpoints. These are called via /custom/... instead of /webapi/v3/.... The Restservice also supports these endpoints and provides the methods deletec(), getc(), headc(), optionsc(), patchc(), postc() and putc() for them. The c at the end of the method name stands for custom. The methods function identically to the non-custom variants, except that the url is adapted.

Type-Safe Methods

From version 2.0 onwards, our module introduces type-safe methods for more reliable endpoint communication, enhancing the previously generic approach like get(). These methods ensure strong typing for both input parameters and return values from REST API calls to the sysHUB server, providing enhanced type safety for your variables.

For a detailed list of these methods, please refer to the README_methods.md file.

Example

Consider the getCurrentUser() method, which specifically targets the currentUser endpoint through an HTTP GET request. The return type is SyshubUserAccount, a data type that includes all properties guaranteed by the sysHUB server. Thus, responses are either a SyshubUserAccount object or an Error object (indicating issues like unauthenticated access). Here's an example usage:

this.restService.getCurrentUser().subscribe((response) => {
  if (response instanceof Error) {
    // Handle failed response
  } else if (response === HttpStatusCode.NotModified) {
    // Entity not changed
  } else {
    // Handle successful response
    // Guaranteed to be a SyshubUserAccount typed object, not an Error.
  }
});

Using sysHUB Server cache

From version 5 of this module, the Etag mechanism, which is also available in the sysHUB Rest API, is taken into account. Basically, this works in such a way that the server delivers an Etag (a hash value) with every response. If the same resource is requested again and the hash value is supplied, the server checks whether the resource has changed. If so, it delivers the resource plus the new Etag as normal. If not, the server returns the HTTP status code 304/Not modified.

The Rest module has now also implemented the corresponding functionality and enables the use of the Etag feature for all GET requests that do not concern custom endpoints. The feature is activated by default and means that in future, in addition to the response from the server or an error, the code 304 can also be returned to the calling function. In this case, the requested resource has not changed and there is no new data.

In order to skip the etag check and force the server to deliver the resource again, set the param clean to true:

this.restService.getCurrentUser(true).subscribe((response) => {
  if (response instanceof Error) {
    // Handle failed response
  } else if (response === HttpStatusCode.NotModified) {
    // Entity not changed
    // Will not happen due to param clean=true
  } else {
    // Handle successful response
    // Guaranteed to be a SyshubUserAccount typed object, not an Error.
  }
});

Credits

This README documentation is for the syshub-rest-module, which facilitates communication with the NT-Ware uniFLOW sysHUB server. While this module is independently developed, it is designed to work with sysHUB, a product of NT-Ware. For more information about NT-Ware and their innovative sysHUB solution, visit their official website:

NT-Ware uniFLOW sysHUB Official Website