org.springframework.batch.poller.Poller Maven / Gradle / Ivy
/*
* Copyright 2006-2018 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.batch.poller;
import java.util.concurrent.Callable;
import java.util.concurrent.Future;
/**
* Interface for polling a {@link Callable} instance provided by the user. Use
* when you need to put something in the background (e.g. a remote invocation)
* and wait for the result, e.g.
*
*
* Poller<Result> poller = ...
*
* final long id = remoteService.execute(); // do something remotely
*
* Future<Result> future = poller.poll(new Callable<Result> {
* public Object call() {
* // Look for the result (null if not ready)
* return remoteService.get(id);
* }
* });
*
* Result result = future.get(1000L, TimeUnit.MILLISECONDS);
*
*
* @author Dave Syer
* @author Mahmoud Ben Hassine
*
*/
public interface Poller {
/**
* Use the callable provided to poll for a non-null result. The callable
* might be executed multiple times searching for a result, but once either
* a result or an exception has been observed the polling stops.
*
* @param callable a {@link Callable} to use to retrieve a result
* @return a future which itself can be used to get the result
* @throws java.lang.Exception allows for checked exceptions
*/
Future poll(Callable callable) throws Exception;
}