nextapp.echo.webcontainer.service.AsyncMonitorService Maven / Gradle / Ivy
/*
* This file is part of the Echo Web Application Framework (hereinafter "Echo").
* Copyright (C) 2002-2009 NextApp, Inc.
*
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (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.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*/
package nextapp.echo.webcontainer.service;
import java.io.IOException;
import nextapp.echo.webcontainer.Connection;
import nextapp.echo.webcontainer.ContentType;
import nextapp.echo.webcontainer.Service;
/**
* Abstract base service for handling server poll requests to determine if any
* asynchronous operations affecting a UserInstance have been
* performed since the last server interaction, such that the client might
* resynchronize with the server.
*
* An instance of this service must be registered with the
* ServiceRegistry if asynchronous polling is required.
*/
public class AsyncMonitorService
implements Service {
/**
* Singleton instance.
*/
public static final Service INSTANCE = new AsyncMonitorService();
/**
* Asynchronous monitoring service identifier.
*/
public static final String SERVICE_ID = "Echo.AsyncMonitor";
/**
* Private constructor: use singleton INSTANCE.
*/
private AsyncMonitorService() { }
/**
* @see Service#getId()
*/
public String getId() {
return SERVICE_ID;
}
/**
* @see Service#getVersion()
*/
public int getVersion() {
return DO_NOT_CACHE;
}
/**
* @see Service#service(nextapp.echo.webcontainer.Connection)
*/
public void service(Connection conn) throws IOException {
conn.setContentType(ContentType.TEXT_XML);
if (conn.getUserInstance().getApplicationInstance().hasQueuedTasks()) {
conn.getWriter().write("");
} else {
conn.getWriter().write("");
}
}
}