In addition to these new features, many aspects of the SDK have been refactored and cleaned up with a strong focus on consistency, immutability, and ease of use. The Developer Preview is your chance to influence the direction of the AWS SDK for Java 2. Your feedback matters to us. Find details on various ways to give feedback at the bottom of this post. We know there are lots of customers who depend on 1. As we get closer to general availability for version 2. The following steps use Maven as an example but you can use any build system that supports as an artifact source Gradle, sbt, etc. These steps assume you have Maven and a Java 8 JDK already installed. See the for a more detailed tutorial on getting started. Under the hood, we use an HTTP client built on top of Netty to make the non-blocking HTTP call. For non-streaming operations, the interfaces are nearly identical to the sync client. The only difference is that a CompletableFuture containing the response is returned immediately instead of blocking the thread until the response is available. Exceptions are delivered by completing the future exceptionally and can be accessed using the appropriate callbacks on the future see. For streaming inputs like the PutObject operation , you must supply an that can produce content incrementally. This is based on the well-known interfaces. In fact, the request provider is simply a of ByteBuffer chunks. The SDK will call subscribe on that Publisher and request chunks of data as its buffer allows. Here we upload a file asynchronously using the PutObject operation in Amazon S3. It handles backpressure and retries automatically, reducing the burden on the developer. We want to support common implementations and sources of data out of the box, so if you have any suggestions or requests, please let us know. Only close the client when you are completely done with it. This response handler has callback methods for various events in the response lifecycle. It follows the same reactive streams model for handling the data. The SDK is the data publisher and the response handler implementation must subscribe to the publisher and request data from it. Consult the Java documentation for a more detailed explanation of how to implement AsyncResponseHandler. In the following example we will use a pre-canned implementation that just emits the data to a file. Only close the client when you are completely done with it FunctionalUtils. The AWS SDK for Java 2. The SDK continues to ship Apache as the default, but you can remove it and replace it with another implementation that conforms to the appropriate SPI. The SDK attempts to load an HTTP implementation from the classpath using the utility. Customers who want to avoid potentially expensive classpath scanning can set the system property to explicitly identify the implementation to use. Finally, for customers wanting precise control over how the HTTP client is created and configured, the SDK accepts either an instance or instance in each service client builder. Passing in an SdkHttpClient enables customers to share a connection pool across multiple service clients for better resource utilization. Configuring HTTP settings Due to the pluggable nature of the HTTP layer, customers who want to configure HTTP specific settings such as socket timeout, proxy settings, etc. In the following examples we show how to configure the default Apache implementation. This allows you to reuse the same connection pool for better resource utilization. To share a client across multiple SDK service clients, you must depend on a specific implementation and create an HTTP client factory for that implementation, as shown above. The interfaces for the factory and client are and , respectively. An implementation built on top of Netty is the default. Add the following to your pom. The following are some of the bigger changes included in the AWS SDK for Java 2. Client Builders In 1. In addition, clients are 100 percent immutable after creation. For a cleaner programming experience, all interaction with the clients is done through interfaces. To obtain an instance of the builder, you can use a static factory method on the client interface like this. You can change the non-HTTP related advanced configuration via the overrideConfiguration method. In the example below, originalRequest is unchanged and a new instance of ListTablesRequest is created and returned. The new Region class looks similar to an enum and has constants for each region. Now, the sync and async clients have additional parameters for streaming operations to accept streamed content PutObject and to process a streamed response GetObject. This content is provided using a new class, , which has overloads for many common sources of data File, String, byte array, ByteBuffer, InputStream. Again, instead of accessing the InputStream from the GetObjectResponse object, you can now provide a implementation to process the response contents. This is a functional interface that provides the unmarshalled GetObjectResponse and the input stream as parameters and returns some transformed value or Void. This transformed value becomes the return value of the getObject method. There are a couple of convenience static factory methods on the interface to create handlers for common situations like dumping the data into a file or writing it to an OutputStream. We use the file one below. Play around with it and let us know what you think. Giving feedback and contributing You can provide feedback to us in several ways. Both positive and negative feedback is appreciated. Public feedback GitHub issues. Customers who are comfortable giving public feedback can open a Github issue in the. This is the preferred mechanism to give feedback so that other customers can engage in the conversation, +1 issues, etc. Issues you open will be evaluated, and included in our roadmap for the GA launch. For informal discussion or general feedback, you may join the for the V2 repo. The Gitter channel is also a great place to get help with the Developer Preview, although feel free to open an issue as well. Private feedback Those who prefer not to give public feedback can instead email the aws-java-sdk-v2-feedback amazon. This list is monitored by the AWS SDK for Java team and will not be shared with anyone outside of AWS. An SDK team member may respond back to ask for clarification or acknowledge that the feedback was received and is being evaluated. Contributing You can open pull requests for fixes or additions to the AWS SDK for Java 2. All pull requests must be submitted under the Apache 2. Accompanying unit tests are appreciated. Amazon Web Services is Hiring. Amazon Web Services AWS is a dynamic, growing business unit within Amazon. We are currently hiring Software Development Engineers, Product Managers, Account Managers, Solutions Architects, Support Engineers, System Engineers, Designers and more. Visit our page to learn more.
