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translation: Added french documentation for several patterns (#2617)
* translate Abstract Document documentation in french * translate Abstract Document documentation in french for issue #2278 * french translation of abstract factory * French translation for active-object * translate Abstract Document documentation in french * translate Abstract Document documentation in french for issue #2278 * french translation of abstract factory * French translation for active-object * tranlate to french: acyclic-visitore, adapter, aggregator-microservice, ambassador, api-gateway, arrange-act-assert, async-method-invocation, balking, bridge.
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---
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title: Async Method Invocation
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category: Concurrency
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language: fr
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tag:
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- Reactive
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---
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## Intention
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Le pattron de conception Asynchronous method invocation est un pattron dans lequel le thread appelé n'est pas bloqué en
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attendant la fin de l'exécution des tâches.
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Ce pattron permet le traitement parallèle de plusieurs tâches indépendantes et récupère les résultats via les callback ou patiente jusqu'à la fin.
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## Explication
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Exemple concret
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> Le lancement de fusées spatiales est une activité passionnante. Le commandant de la mission donne
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> l'ordre de lancement et, après un temps indéterminé, la fusée réussit son lancement ou échoue lamentablement.
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En clair
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> Asynchronous method invocation démarre l'exécution de la tâche et retourne directement avant la fin de l'exécution de la tâche.
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> Les résultats de l'exécution des tâches sont retournés après.
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Wikipedia dit
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> Dans la programmation multithread, asynchronous method invocation (AMI), également connue sous le nom de asynchronous method calls
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> ou le pattron asynchronous, est un pattron de conception dans lequel le site d'appel n'est pas bloqué en attendant que le code appelé se termine.
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> Au lieu de cela, le thread appelant est informé de l'arrivée de la réponse. L'interrogation pour une réponse est une option non souhaitée.
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**Exemple de programme**
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Dans cet exemple, nous lançons des fusées spatiales et déployons des rovers lunaires.
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L'application démontre le pattron async method invocation. Les éléments clés de ce modèle sont `AsyncResult`
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qui est un conteneur intermédiaire pour une valeur évaluée de manière asynchrone, `AsyncCallback` qui peut être fourni
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pour être exécuté à la fin de la tâche et `AsyncExecutor` qui gère l'exécution des tâches asynchrones. qui gère l'exécution des tâches asynchrones.
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```java
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public interface AsyncResult<T> {
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boolean isCompleted();
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T getValue() throws ExecutionException;
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void await() throws InterruptedException;
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}
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```
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```java
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public interface AsyncCallback<T> {
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void onComplete(T value, Optional<Exception> ex);
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}
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```
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```java
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public interface AsyncExecutor {
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<T> AsyncResult<T> startProcess(Callable<T> task);
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<T> AsyncResult<T> startProcess(Callable<T> task, AsyncCallback<T> callback);
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<T> T endProcess(AsyncResult<T> asyncResult) throws ExecutionException, InterruptedException;
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}
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```
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`ThreadAsyncExecutor` est une implémentation de `AsyncExecutor`. Certains de ses éléments clés sont décrits ci-dessous.
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```java
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public class ThreadAsyncExecutor implements AsyncExecutor {
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@Override
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public <T> AsyncResult<T> startProcess(Callable<T> task) {
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return startProcess(task, null);
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}
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@Override
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public <T> AsyncResult<T> startProcess(Callable<T> task, AsyncCallback<T> callback) {
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var result = new CompletableResult<>(callback);
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new Thread(
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() -> {
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try {
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result.setValue(task.call());
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} catch (Exception ex) {
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result.setException(ex);
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}
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},
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"executor-" + idx.incrementAndGet())
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.start();
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return result;
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}
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@Override
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public <T> T endProcess(AsyncResult<T> asyncResult)
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throws ExecutionException, InterruptedException {
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if (!asyncResult.isCompleted()) {
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asyncResult.await();
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}
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return asyncResult.getValue();
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}
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}
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```
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Nous sommes ensuite prêts à lancer quelques fusées pour voir comment tout fonctionne ensemble.
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```java
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public static void main(String[] args) throws Exception {
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// construct a new executor that will run async tasks
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var executor = new ThreadAsyncExecutor();
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// start few async tasks with varying processing times, two last with callback handlers
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final var asyncResult1 = executor.startProcess(lazyval(10, 500));
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final var asyncResult2 = executor.startProcess(lazyval("test", 300));
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final var asyncResult3 = executor.startProcess(lazyval(50L, 700));
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final var asyncResult4 = executor.startProcess(lazyval(20, 400), callback("Deploying lunar rover"));
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final var asyncResult5 =
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executor.startProcess(lazyval("callback", 600), callback("Deploying lunar rover"));
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// emulate processing in the current thread while async tasks are running in their own threads
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Thread.sleep(350); // Oh boy, we are working hard here
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log("Mission command is sipping coffee");
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// wait for completion of the tasks
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final var result1 = executor.endProcess(asyncResult1);
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final var result2 = executor.endProcess(asyncResult2);
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final var result3 = executor.endProcess(asyncResult3);
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asyncResult4.await();
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asyncResult5.await();
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// log the results of the tasks, callbacks log immediately when complete
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log("Space rocket <" + result1 + "> launch complete");
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log("Space rocket <" + result2 + "> launch complete");
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log("Space rocket <" + result3 + "> launch complete");
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}
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```
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Voici la sortie de la console du programme.
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```java
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21:47:08.227 [executor-2] INFO com.iluwatar.async.method.invocation.App - Space rocket <test> launched successfully
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21:47:08.269 [main] INFO com.iluwatar.async.method.invocation.App - Mission command is sipping coffee
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21:47:08.318 [executor-4] INFO com.iluwatar.async.method.invocation.App - Space rocket <20> launched successfully
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21:47:08.335 [executor-4] INFO com.iluwatar.async.method.invocation.App - Deploying lunar rover <20>
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21:47:08.414 [executor-1] INFO com.iluwatar.async.method.invocation.App - Space rocket <10> launched successfully
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21:47:08.519 [executor-5] INFO com.iluwatar.async.method.invocation.App - Space rocket <callback> launched successfully
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21:47:08.519 [executor-5] INFO com.iluwatar.async.method.invocation.App - Deploying lunar rover <callback>
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21:47:08.616 [executor-3] INFO com.iluwatar.async.method.invocation.App - Space rocket <50> launched successfully
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21:47:08.617 [main] INFO com.iluwatar.async.method.invocation.App - Space rocket <10> launch complete
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21:47:08.617 [main] INFO com.iluwatar.async.method.invocation.App - Space rocket <test> launch complete
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21:47:08.618 [main] INFO com.iluwatar.async.method.invocation.App - Space rocket <50> launch complete
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```
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# Diagramme de classes
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## Application
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Utilisez le pattron async method invocation lorsque
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* Vous avez plusieurs tâches indépendantes qui peuvent être exécutées en parallèle
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* Vous devez améliorer les performances d'un groupe de tâches séquentielles
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* Vous disposez d'une capacité de traitement limitée ou de tâches à long terme et l'appelant ne doit pas attendre que les tâches soient exécutées.
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## Application concrete
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* [FutureTask](http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/FutureTask.html)
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* [CompletableFuture](https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CompletableFuture.html)
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* [ExecutorService](http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ExecutorService.html)
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* [Task-based Asynchronous Pattern](https://msdn.microsoft.com/en-us/library/hh873175.aspx)
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