software.amazon.awssdk.services.ec2.paginators

Class DescribeInstancesPublisher

java.lang.Object

software.amazon.awssdk.services.ec2.paginators.DescribeInstancesPublisher

All Implemented Interfaces:

org.reactivestreams.Publisher<DescribeInstancesResponse>, SdkPublisher<DescribeInstancesResponse>

@Generated(value="software.amazon.awssdk:codegen")
public class DescribeInstancesPublisher
extends Object
implements SdkPublisher<DescribeInstancesResponse>

Represents the output for the Ec2AsyncClient.describeInstancesPaginator(software.amazon.awssdk.services.ec2.model.DescribeInstancesRequest) operation which is a paginated operation. This class is a type of Publisher which can be used to provide a sequence of DescribeInstancesResponse response pages as per demand from the subscriber.

When the operation is called, an instance of this class is returned. At this point, no service calls are made yet and so there is no guarantee that the request is valid. If there are errors in your request, you will see the failures only after you start streaming the data. The subscribe method should be called as a request to start streaming data. For more info, see Publisher.subscribe(org.reactivestreams.Subscriber). Each call to the subscribe method will result in a new Subscription i.e., a new contract to stream data from the starting request.

The following are few ways to use the response class:

1) Using the forEach helper method

 
 software.amazon.awssdk.services.ec2.paginators.DescribeInstancesPublisher publisher = client.describeInstancesPaginator(request);
 CompletableFuture<Void> future = publisher.forEach(res -> { // Do something with the response });
 future.get();
 
 

2) Using a custom subscriber

 
 software.amazon.awssdk.services.ec2.paginators.DescribeInstancesPublisher publisher = client.describeInstancesPaginator(request);
 publisher.subscribe(new Subscriber<software.amazon.awssdk.services.ec2.model.DescribeInstancesResponse>() {
 
 public void onSubscribe(org.reactivestreams.Subscriber subscription) { //... };
 
 
 public void onNext(software.amazon.awssdk.services.ec2.model.DescribeInstancesResponse response) { //... };
 });
 

As the response is a publisher, it can work well with third party reactive streams implementations like RxJava2.

Note: If you prefer to have control on service calls, use the #describeInstances(software.amazon.awssdk.services.ec2.model.DescribeInstancesRequest) operation.

Constructor Summary

Constructors

Constructor and Description
DescribeInstancesPublisher(Ec2AsyncClient client, DescribeInstancesRequest firstRequest)

Method Summary

Modifier and Type	Method and Description
SdkPublisher<Reservation>	reservations() Returns a publisher that can be used to get a stream of data.
void	subscribe(org.reactivestreams.Subscriber<? super DescribeInstancesResponse> subscriber)

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface software.amazon.awssdk.core.pagination.async.SdkPublisher

forEach

Constructor Detail

DescribeInstancesPublisher

public DescribeInstancesPublisher(Ec2AsyncClient client,
                                  DescribeInstancesRequest firstRequest)

Method Detail

subscribe

public void subscribe(org.reactivestreams.Subscriber<? super DescribeInstancesResponse> subscriber)

Specified by:

subscribe in interface org.reactivestreams.Publisher<DescribeInstancesResponse>

reservations

public final SdkPublisher<Reservation> reservations()

Returns a publisher that can be used to get a stream of data. You need to subscribe to the publisher to request the stream of data. The publisher has a helper forEach method that takes in a Consumer and then applies that consumer to each response returned by the service.