I am new and learning Nest JS, i came from Java Springboot before. In Java Springboot, if my Rest API have one request let's say my API will always have 10 second to finish, the first one won't block the second request, the second request just start without waiting for the first request to finish.
When i trying Nest JS, i have read that Nest JS is build on top of Nodejs which is single threaded, so if the same condition just like my Java Springboot REST API happend, it will block the first request and wait it to finish then process the second one right?
But when i read in some articles, we can write the non-blocking one, here is what i try :
@Controller()
export class AppController {
@Get()
findAllX(): Observable<string> {
console.log('Before sleep');
// Sleep for 10 seconds (10000 milliseconds) asynchronously
// here i mocking my slow database query
return timer(10000).pipe(
switchMap(() => of('Sleep completed'))
);
}
@Get('test')
async findAllY(): Promise<string> {
console.log('Before sleep');
// Sleep for 10 seconds (10000 milliseconds) asynchronously
// here i mocking my slow database query
await new Promise((resolve) => setTimeout(resolve, 10000));
console.log('After sleep');
return 'Sleep completed';
}
}
as you can see i mocking my slow database query using timer and setTimeout, my first function named "findAllX" is written and return as Observable, but then i request TWICE for this REST API, it wait for the first one to complete then start the second one
it applied the same with Promise approach.
How can i make it handle request like java springboot?
**Notes :
cmd to init my project : nest new project-name --strict
cmd to start my project : npm run start:dev -- -b swc
Testing scenario :
- Using Web Browser :
since my API is writtin with Get Request, i use browser and open two tab then i hit my API request at the first tab then switch to the second one. When i see at my terminal, the console.log of the second request doesn't print console.log until the first request to finish.
- But.. When i try using POSTMAN :
It worked! it didn't wait the first one to finish, i try both approach it worked.
- I write simple angular client then hit my API, here is the result :
i clicked it rapidly, as you can see the api getting slower 10 second for 3 request and the rest is not! the connection id written the same id for the first 3 request and you can see the waterfall, what happened?
UPDATE Angular Codes :
api.service.ts :
@Injectable({
providedIn: 'root'
})
export class ApiService {
private apiUrl = 'http://localhost:3000';
constructor(private http: HttpClient) {}
getData(): Observable<any> {
return this.http.get(`${this.apiUrl}`);
}
}
here is my api-button.component.ts :
@Component({
selector: 'app-api-button',
templateUrl: './api-button.component.html',
styleUrls: ['./api-button.component.scss']
})
export class ApiButtonComponent {
responseData: any;
constructor(private apiService: ApiService) {}
fetchData(): void {
this.apiService.getData().subscribe(
(data) => {
this.responseData = data;
// You can process the API response data here
},
(error) => {
console.error('Error:', error);
}
);
}
}
here is the html :
<div>
<button (click)="fetchData()">Fetch Data</button>
</div>
