Async.java

/*
 * Copyright (c) OSGi Alliance 2015. All Rights Reserved.
 *
 * 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
 *
 *      http://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.osgi.service.async;

import org.osgi.annotation.versioning.ProviderType;
import org.osgi.framework.ServiceReference;
import org.osgi.util.promise.Promise;

/**
 * The Async Service, as defined in OSGi RFC 204
 * https://github.com/osgi/design/tree/master/rfcs/rfc0206
 */
@ProviderType
public interface Async {
    
    /**
     * Create a mediated object for asynchronous calls
     *
     * @param target The object to mediate
     * @param iface The type that the mediated object should implement or extend
     * @return A mediated object
     * @throws IllegalArgumentException if mediation fails
     */
    <T> T mediate(T target, Class<T> iface);
    
    /**
     * Create a mediated object for asynchronous calls
     *
     * @param target The service reference to mediate
     * @param iface The type that the mediated object should implement or extend
     * @return A mediated service
     * @throws IllegalArgumentException if mediation fails
     */
    <T> T mediate(ServiceReference<? extends T> target, Class<T> iface);
    
    /**
     * Asynchronously run the last method call registered by a mediated object,
     * returning the result as a Promise.
     *
     * @param r the return value of the mediated call
     * @return a Promise
     */
    <R> Promise<R> call(R r);
    
    /**
     * Asynchronously run the last method call registered by a mediated object,
     * returning the result as a Promise.
     *
     * @return a Promise
     */
    Promise<?> call();
    
    /**
     * Asynchronously run the last method call registered by a mediated object,
     * ignoring the return value.
     *
     * @return a Promise indicating whether the task started successfully
     */
    Promise<Void> execute();
    
}