Implementing asynchronous REST clients can be a powerful strategy for microservices-based applications. Asynchronous clients don’t need to wait for a response to continue working. Therefore, microservices in an app can continue to process and send data, even when one of their partner services runs into trouble. This capability provides more reliable service to the user and can be especially valuable in cases where service availability is low or overloaded with demand.
For example, asynchronous clients might be implemented within a travel service app that makes REST calls to an airline service, hotel service, and car rental service. If the hotel service experiences a lag, the airline and car rental service are able to continue working. For an in-depth look at how to implement asynchronous clients in this travel app example, check out Andy McCright’s blog post on Asynchronous REST with JAX-RS and MicroProfile.
Asynchronous REST clients with MicroProfile Rest Client
Callbacks are functions that run after another function completes. With MicroProfile Rest Client, asynchronous clients rely on callbacks to manage the transfer of data between microservices. The return type of the interface method determines whether a RESTful service is invoked synchronously or asynchronously. If the return type is a CompletionStage, the service is invoked asynchronously. A CompletionStage return type acts as a promise to the service that a particular piece of code must be executed at some point in the future. A wide range of callbacks can be attached to a CompletionStage return type, which can enable different functions after the code executes. Therefore, non-blocking systems can be implemented among microservices in an application.
MicroProfile Rest Client is enabled to set up both synchronous and asynchronous REST clients. You can use MicroProfile Rest Client with Open Liberty by enabling the mpRestClient feature in your server.xml file.
The following example shows a MicroProfile Rest Client interface that has methods to invoke the same remote service both synchronously and asynchronously:
@Path("/somePath")public interface MyClient { @GET Widget getSync(); @GET CompletionStage<Widget> getAsync();}
The following example shows the code to invoke that remote service:
MyClient client = RestClientBuilder.newBuilder().baseUri(someUri).build(MyClient.class);CompletionStage<Widget> cs = client.getAsync();// while that request is running, let's invoke it synchronously too:Widget widgetSync = client.getSync(); // now we have to wait until the request completes// done. So now we can see the results of the async request// that was processing while we did the sync request:Widget widgetAsync = toCompletableFuture().get();assertEquals(widgetAsync, widgetSync);
Asynchronous REST clients with JAX-RS
With JAX-RS clients, you need to explicitly build an async client with an API call, as shown in the following example:
Client client = ClientBuilder.newClient();WebTarget target = client.target(url);Invoker.Builder builder = target.request();AsyncInvoker asyncInvoker = builder.async();
Then, you can choose whether to provide a callback or get a Future return type, as shown in the following example.
Future<MyResponseObject> future = asyncInvoker.get(MyResponseObject.class);// orFuture<MyResponseObject> future = asyncInvoker.get( new InvocationCallback<MyResponseObject>() { @Override public void completed(MyResponseObject o) { // do something with o } @Override public void failed(Throwable t) { // handle the failed request/response }});
FAQs
Open Liberty is a lightweight open source Java runtime that is built by using modular features. WebSphere Liberty is a commercial version of Open Liberty. Liberty provides an efficient packaging pipeline for Docker containers, making it a great operational fit for cloud environments.
Does IBM support Open Liberty? ›
You get IBM support for Open Liberty if you buy WebSphere Hybrid Edition. This gives you fast, dedicated help, 24x7 help for business-critical issues, fixes for previous releases, and you can open a case online, by chat, or by phone.
Is open liberty free? ›
Open Liberty is open source and free to use. However, when you purchase a WebSphere Application Server- Base or WebSphere Application Server Network Deployment license, you also get IBM support for your Open Liberty instances. You can apply a license by using the License Metric Tool.
What is the open liberty server? ›
Open Liberty is a lightweight Java runtime for building cloud-native applications and microservices. With Open Liberty, it's easy to add and remove modular features from the latest versions of Jakarta EE and Eclipse MicroProfile.
Why use open liberty? ›
Open Liberty is an open framework for the Java ecosystem that allows developing microservices using features of the Eclipse MicroProfile and Jakarta EE platforms. It is a flexible, fast, and lightweight Java runtime that seems promising for cloud-native microservices development.
Is liberty a freedom or a right? ›
As used in the Constitution, liberty means freedom from arbitrary and unreasonable restraint upon an individual. Freedom from restraint refers to more than just physical restraint, but also the freedom to act according to one's own will.
What is the meaning of WebSphere? ›
IBM WebSphere refers to a brand of proprietary computer software products in the genre of enterprise software known as "application and integration middleware". These software products are used by end-users to create and integrate applications with other applications.
What is the difference between Tomcat and WebSphere? ›
Simple answer is, tomcat only has a web container whereas the websphere has both the web and EJB container which could support more complex applications. If you are a web developer and needs to test your coding with little investment you could go for a Tomcat.
What is the latest WebSphere version? ›
Version 9.0. 5 is the newest release of WebSphere Application Server and its associated editions: WebSphere Liberty, WebSphere Application Server Network Deployment and WebSphere Application Server Family Edition.
What is the Admin Center in Open Liberty? ›
The Admin Center is a web-based graphical user interface (GUI) for Open Liberty servers. You can use the Admin Center to manage your server configuration, OpenID Connect permissions, and Java batch jobs.
The default port for debugging is 7777 . If the default port is not available, dev mode selects a random port to use as the port for debugging.
Is Liberty server free? ›
For more information, see Where to find Liberty documentation. Open Liberty is open source and free to use.
What is the true meaning of liberty? ›
liberty noun (FREEDOM)
the freedom to live as you wish or go where you want: For most citizens, liberty means the freedom to practice their religious or political beliefs.
What is the difference between the concept of liberty and the concept of freedom? ›
Liberty is the moral imperative to act in a just and responsible way, even when it might be easier or more convenient to do otherwise. Liberty is the moral imperative to act in a just and responsible way." Freedom, on the other hand, is an external force that enables us to do what we want.
What is liberty in democracy? ›
While democracy has to do with the selection of rulers or policies, liberty refers to the freedom to engage in certain behaviors or to hold and express views without governmental interference.
What is the difference between Tomcat and liberty? ›
Tomcat's lightweight nature and focused use case make it more suitable for environments with limited resources or when running on lower-spec hardware. Websphere Liberty, being a full application server, has a larger memory footprint to accommodate the additional enterprise features it provides.
