content: package com.iluwatar.async.method.invocation;
  
  import java.util.concurrent.Callable;
  import java.util.concurrent.ExecutionException;
  
  public interface AsyncExecutor {
  
  	/**
  	 * Starts processing of an async task. Returns immediately with async result.
  	 *
  	 * @param task task to be executed asynchronously
  	 * @return async result for the task
  	 */
  	<T> AsyncResult<T> startProcess(Callable<T> task);
  
  	/**
  	 * Starts processing of an async task. Returns immediately with async result. Executes callback
  	 * when the task is completed.
  	 *
  	 * @param task task to be executed asynchronously
  	 * @param callback callback to be executed on task completion
  	 * @return async result for the task
  	 */
  	<T> AsyncResult<T> startProcess(Callable<T> task, AsyncCallback<T> callback);
  
  	/**
  	 * Ends processing of an async task. Blocks the current thread if necessary and returns the
  	 * evaluated value of the completed task.
  	 *
  	 * @param asyncResult async result of a task
  	 * @return evaluated value of the completed task
  	 * @throws ExecutionException if execution has failed, containing the root cause
  	 * @throws InterruptedException if the execution is interrupted
  	 */
  	<T> T endProcess(AsyncResult<T> asyncResult) throws ExecutionException, InterruptedException;
  
  }
  