Merge "A little more improvement of the Service javadoc." into froyo

import java.io.PrintWriter;

/**

 * A Service is an application component that runs in the background, not

 * interacting with the user, for an indefinite period of time.  Each service

 * A Service is an application component representing either an application's desire

 * to perform a longer-running operation while not interacting with the user

 * or to supply functionality for other applications to use.  Each service

 * class must have a corresponding

 * {@link android.R.styleable#AndroidManifestService <service>}

 * declaration in its package's <code>AndroidManifest.xml</code>.  Services

 * networking) operations, it should spawn its own thread in which to do that

 * work.  More information on this can be found in

 * <a href="{@docRoot}guide/topics/fundamentals.html#procthread">Application Fundamentals:

 * Processes and Threads</a>.</p>

 * Processes and Threads</a>.  The {@link IntentService} class is available

 * as a standard implementation of Service that has its own thread where it

 * schedules its work to be done.</p>

 * 

 * <p>The Service class is an important part of an

 * <a href="{@docRoot}guide/topics/fundamentals.html#lcycles">application's overall lifecycle</a>.</p>

 * 

 * <p>Topics covered here:

 * <ol>

 * <li><a href="#WhatIsAService">What is a Service?</a>

 * <li><a href="#ServiceLifecycle">Service Lifecycle</a>

 * <li><a href="#Permissions">Permissions</a>

 * <li><a href="#ProcessLifecycle">Process Lifecycle</a>

 * <li><a href="#RemoteMessengerServiceSample">Remote Messenger Service Sample</a>

 * </ol>

 * 

 * <a name="WhatIsAService"></a>

 * <h3>What is a Service?</h3>

 * 

 * <p>Most confusion about the Service class actually revolves around what

 * it is <em>not</em>:</p>

 * 

 * <ul>

 * <li> A Service is <b>not</b> a separate process.  The Service object itself

 * does not imply it is running in its own process; unless otherwise specified,

 * it runs in the same process as the application it is part of.

 * <li> A Service is <b>not</b> a thread.  It is not a means itself to do work off

 * of the main thread (to avoid Application Not Responding errors).

 * </ul>

 * 

 * <p>Thus a Service itself is actually very simple, providing two main features:</p>

 * 

 * <ul>

 * <li>A facility for the application to tell the system <em>about</em>

 * something it wants to be doing in the background (even when the user is not

 * directly interacting with the application).  This corresponds to calls to

 * {@link android.content.Context#startService Context.startService()}, which

 * ask the system to schedule work for the service, to be run until the service

 * or someone else explicitly stop it.

 * <li>A facility for an application to expose some of its functionality to

 * other applications.  This corresponds to calls to

 * {@link android.content.Context#bindService Context.bindService()}, which

 * allows a long-standing connection to be made to the service in order to

 * interact with it.

 * </ul>

 * 

 * <p>When a Service component is actually created, for either of these reasons,

 * all that the system actually does is instantiate the component

 * and call its {@link #onCreate} and any other appropriate callbacks on the

 * main thread.  It is up to the Service to implement these with the appropriate

 * behavior, such as creating a secondary thread in which it does its work.</p>

 * 

 * <p>Note that because Service itself is so simple, you can make your

 * interaction with it as simple or complicated as you want: from treating it

 * as a local Java object that you make direct method calls on (as illustrated

 * by <a href="#LocalServiceSample">Local Service Sample</a>), to providing

 * a full remoteable interface using AIDL.</p>

 * 

 * <a name="ServiceLifecycle"></a>

 * <h3>Service Lifecycle</h3>

 *