Compare2b.java

package test;

import java.util.concurrent.*;
import java.util.concurrent.atomic.AtomicReference;

public class Compare2Wrappers {
    // I/O operations: non-blocking, asynchronous
    CompletableFuture<String> sendHttpGet(String url) { return null; }

    // the business logic: asynchronous, as the type suggests
    CompletableFuture<String> runBusinessProcess(long userId) throws InterruptedException {
        // running two API calls; if threads are available, these will run in parallel
        CompletableFuture<String> profileResult = 
            sendHttpGet("http://profile_service/get/" + userId);
        CompletableFuture<String> friendsResult = 
            sendHttpGet("http://friends_service/get/" + userId);

        // composing both futures into a single result
        return profileResult.thenCompose(profile ->
                friendsResult.thenApply(friends ->
                        "Profile: " + profile + ", friends: " + friends));
    }
}