avoid Angular 2 http method to fire an ajax everytime a component subscribes to it

someComponent.ts

export someClass {

private relplay: ReplaySubject<any> = new ReplaySubject<any>(1);

subscribeToReplay(): ReplaySubject<any> {

    return this.replay;
}


callHttpRequest(someParams) {
    
    this.http.post( ... ).subscribe(
        (response) => {
            // some actions
            this.replay.next(response); // instead of response here may be other object or variables
        }
    );
}
....
export secondClass {

let subscription: Subscription = someClass.subscribeToReplay().subscribe(
    (response) => {
        // on response actions here
    }
);

....

someClass.callHttpRequest({some params});