Push promises received, if any, are handled by the given PushPromiseHandler. For each resource, the server sends a special request, known as a push promise to the client. It is really the multiplexing feature of HTTP/2 that allows us to forget about resource bundling. It allows the server to вЂњpushвЂќ content to the client additional resources while requesting the primary resource, saving more roundtrip and as a result improves performance in page rendering. New HttpClient supports push promises through PushPromiseHandler interface. The new API can also deal with multiple responses, and stream the request and response bodies: So, now we can use sendAsync(.) method - which returns CompletableFeature - to process a request asynchronously: CompletableFuture> response = HttpClient.newBuilder() However, it has a lot of drawbacks especially when we are processing large amounts of data.

This call returns an HttpResponse object, and we're sure that the next instruction from our application flow will be run only when the response is already here. Up until now, the send(.) method naturally waits for a response: HttpResponse response = HttpClient.newBuilder() sendAsync(вЂ¦) вЂ“ asynchronously (doesn't wait for the response, non-blocking).send(вЂ¦) вЂ“ synchronously (blocks until the response comes).New HttpClient provides two possibilities for sending a request to a server: The request body published by a concatenation publisher is logically equivalent to the request body that would have been published by concatenating all the bytes of each publisher in sequence. Note: In JDK 16, there's a new (BodyPublisherвЂ¦) method that helps us building a request body from the concatenation of the request bodies published by a sequence of publishers. noBody(): HttpRequest request = HttpRequest.newBuilder() In case we don't need a body, we can simply pass in an HttpRequest.BodyPublishers. FileProcessor вЂ“ reads body from a file at the given path, created with.ByteArrayProcessor вЂ“ reads body from a byte array, created with.InputStreamProcessor вЂ“ reads body from an InputStream, created with.StringProcessor вЂ“ reads body from a String, created with.The new API provides a number of BodyPublisher implementations out-of-the-box that simplify passing the request body:

Problems With the Pre-Java 11 HTTP Client The core classes and interface providing the core functionality include:

The new APIs provide native support for HTTP 1.1/2 WebSocket.

The new HTTP client API provides a standard way to perform HTTP network operations with support for modern Web features such as HTTP/2, without the need to add third-party dependencies.

Asynchronous calls are implemented using CompletableFuture.The CompletableFuture implementation takes care of applying each stage once the previous one has finished, so this whole flow is asynchronous.

As of Java 11, the API is now fully asynchronous (the previous HTTP/1.1 implementation was blocking).

This is achieved by introducing a number of changes such as stream multiplexing, header compression and push promises.

The newer version of the HTTP protocol is designed to improve the overall performance of sending requests by a client and receiving responses from the server.

The incubated HTTP API from Java 9 is now officially incorporated into the Java SE API.

Java 11 http client