Is it good to call subscribe inside subscribe?

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The correct way is to compose the various observables in some manner then subscribe to the overall flow — how you compose them will depend on your exact requirements.

If you can do them all in parallel:

forkJoin(
  this.service.service1(), this.service.service2(), this.service.service3()
).subscribe((res) => {
  this.funcA(res[0], res[1], res[2]);
});

If each depends on the result of the previous, you can use mergeMap (formerly known as flatMap) or switchMap:

this.service.service1().pipe(
  mergeMap((res1) => this.service.service2(res1)),
  mergeMap((res2) => this.service.service3(res2))
).subscribe((res3) => {
  // Do something with res3.
});

… and so on. There are many operators to compose observables to cover lots of different scenarios.

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