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Cristal-ise is a description-driven software platform originally developed to track the construction of the CMS ECAL detector of the LHC at CERN. This is its core library, known as the kernel, which manages business objects called Items. Items are entirely configured from data, called descriptions, held in other Items. Every change of a state in an Item is a consequence of an execution of an activity in that Item's lifecycle, meaning that Cristal-ise applications are completely traceable, even in their design. It also supports extensive versioning of Item description data, giving the system a high level of flexibility.

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/** * This file is part of the CRISTAL-iSE kernel. * Copyright (c) 2001-2015 The CRISTAL Consortium. All rights reserved. * * This library is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License as published * by the Free Software Foundation; either version 3 of the License, or (at * your option) any later version. * * This library is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; with out even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public * License for more details. * * You should have received a copy of the GNU Lesser General Public License * along with this library; if not, write to the Free Software Foundation, * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. * * http://www.fsf.org/licensing/licenses/lgpl.html */ /** * The Proxy API is a major part of the client-side functionality of the * CRISTAL API, which provides client-side proxy objects that represent the * Items and Agents on the server. It is the main entry point for many * components, such as Scripts and Job execution. An AgentProxy is returned on * login, and should be used as the root for all user-based CRISTAL interactions. * * The Proxy API provides the following functionality: * * * Transparent storage integration - Combines direct database access * with remote calls to data retrieval methods on the Items. This allows client * processes to load Item data directly from databases whenever possible * without bothering the CRISTAL server. For example, the LDAP Lookup * implementation allows client processes to load Item Properties directly from * the LDAP server. * * Data object browsing and loading - The proxy objects allow client * processes to browse through the storage cluster structure beneath the Item, * and access the objects directly without having to unmarshall their XML forms. * All object types have their own get methods, so there's no need to construct * their paths nor cast. * * Item object and directory change notification - When a proxy * object is created, it notifies the CRISTAL server that its Item is located * on, and it notified of all additions, deletions and modifications of objects * within that Item so it can remain up-to-date. Client applications may use * the {@link ProxyObserver} interface to be notified of changes, using * {@link MemberSubscription} instances to set up push subscriptions to cluster * contents. It also provides a mechanism for subscribing to directory paths, * so that domain tree browsers can implement asynchronous loading and update * themselves when the tree changes. * * Job querying - Job objects may be retrieved directly from an * ItemProxy, and may also be filtered by Activity name. * * Job execution - The {@link AgentProxy} provides the main * execution method for Jobs. This method performs outcome validation and * executes required CRISTAL Scripts in the client process before the execution * is requested on the server. Additional execution methods to call Predefined * Steps are also available. * * Utility methods for resolution and marshalling - The AgentProxy * provides utility methods for finding Items in the directory by name, path, * or system key, and gives access to the Castor XML marshalling system to * transform CRISTAL objects to XML and back again. * *

The core object of the Proxy API is the ProxyManager, which is initialized * as a static member of the Gateway on initialization. This object can be used * to create a Proxy object from a Path from the directory, and maintains a * connection to the server called the Proxy Update Notification Channel, * through which it subscribes to Items it holds proxies for so it can be * informed of changes to Item data through {@link ProxyMessage} objects. * */ package org.cristalise.kernel.entity.proxy;