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Future in WebApp (Java)

Future in WebApp (Java)

Short description about Future and CompletableFuture

Kengo TODA

July 17, 2016

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  1. What is Future? • Proxy interface to get result of

    async operation • Similar with JavaScript’s Promise
  2. How to implement method which returns Future instance? • Asynchronous

    Method Invocation (Java EE 6) • Creating Asynchronous Methods (Spring Framework)
  3. What is CompletableFuture • New class from Java8, implements Future

    interface • Similar with ListenableFuture in Guava and Spring Framework
  4. When we use them? • When call async I/O •

    Datastore • Message Queue • Cache • RESTful API
  5. Example: When we use them? • If you are service

    provider, • Public service API (interface for user) should return CompletableFuture instance if it may use I/O internally. • Then during I/O is running, your user can use current thread for other usage.
  6. Keywords to google • Promise, Future • CompletableFuture • ListenableFuture

    (Guava & Spring Framework) • Function composition