001package org.apache.turbine.services.pull;
002
003
004/*
005 * Licensed to the Apache Software Foundation (ASF) under one
006 * or more contributor license agreements.  See the NOTICE file
007 * distributed with this work for additional information
008 * regarding copyright ownership.  The ASF licenses this file
009 * to you under the Apache License, Version 2.0 (the
010 * "License"); you may not use this file except in compliance
011 * with the License.  You may obtain a copy of the License at
012 *
013 *   http://www.apache.org/licenses/LICENSE-2.0
014 *
015 * Unless required by applicable law or agreed to in writing,
016 * software distributed under the License is distributed on an
017 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
018 * KIND, either express or implied.  See the License for the
019 * specific language governing permissions and limitations
020 * under the License.
021 */
022
023
024import org.apache.turbine.pipeline.PipelineData;
025import org.apache.turbine.services.Service;
026import org.apache.turbine.util.RunData;
027import org.apache.velocity.context.Context;
028
029/**
030 * The Pull Service manages the creation of application
031 * tools that are available to all templates in a
032 * Turbine application. By using the Pull Service you
033 * can avoid having to make Screens to populate a
034 * context for use in a particular template. The Pull
035 * Service creates a set of tools, as specified in
036 * the TR.props file.
037 *
038 * These tools can have global scope, request scope,
039 * authorized or session scope (i.e. stored in user temp hashmap)
040 * or persistent scope (i.e. stored in user perm hashmap)
041 *
042 * The standard way of referencing these global
043 * tools is through the toolbox handle. This handle
044 * is typically $toolbox, but can be specified in the
045 * TR.props file.
046 *
047 * So, for example, if you had a UI Manager tool
048 * which created a set of UI attributes from a
049 * properties file, and one of the properties
050 * was 'bgcolor', then you could access this
051 * UI attribute with $ui.bgcolor. The identifier
052 * that is given to the tool, in this case 'ui', can
053 * be specified as well.
054 *
055 * @author <a href="mailto:jvanzyl@periapt.com">Jason van Zyl</a>
056 * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
057 * @author <a href="mailto:peter@courcoux.biz">Peter Courcoux</a>
058 * @version $Id$
059 */
060public interface PullService
061        extends Service
062{
063    /** The key under which this service is stored in TurbineServices. */
064    String SERVICE_NAME = "PullService";
065
066    /** Property Key for the global tools */
067    String GLOBAL_TOOL = "tool.global";
068
069    /** Property Key for the request tools */
070    String REQUEST_TOOL = "tool.request";
071
072    /** Property Key for the session tools */
073    String SESSION_TOOL = "tool.session";
074
075    /** Property Key for the authorized tools */
076    String AUTHORIZED_TOOL = "tool.authorized";
077
078    /** Property Key for the persistent tools */
079    String PERSISTENT_TOOL = "tool.persistent";
080
081    /** Property tag for application tool resources directory */
082    String TOOL_RESOURCES_DIR_KEY = "tools.resources.dir";
083
084    /**
085     * Default value for the application tool resources. This is relative
086     * to the webapp root
087     */
088    String TOOL_RESOURCES_DIR_DEFAULT = "resources";
089
090    /**
091     * Property tag for per request tool refreshing (for obvious reasons
092     * has no effect for per-request tools)
093     */
094    String TOOLS_PER_REQUEST_REFRESH_KEY = "tools.per.request.refresh";
095
096    /** Default value for per request tool refreshing */
097    boolean TOOLS_PER_REQUEST_REFRESH_DEFAULT = false;
098
099    /** prefix for key used in the session to store session scope pull tools */
100    String SESSION_TOOLS_ATTRIBUTE_PREFIX = "turbine.sessiontools.";
101
102    /**
103     * Get the context containing global tools that will be
104     * use as part of the Turbine Pull Model.
105     *
106     * @return A Context object which contains the
107     *         Global Tool instances.
108     */
109    Context getGlobalContext();
110
111    /**
112     * Populate the given context with all request, session, authorized
113     * and persistent scope tools (it is assumed that the context
114     * already wraps the global context, and thus already contains
115     * the global tools).
116     *
117     * @param context a Velocity Context to populate
118     * @param pipelineData a RunData object for request specific data
119     */
120     void populateContext(Context context, PipelineData pipelineData);
121
122     /**
123      * Populate the given context with all request, session, authorized
124      * and persistent scope tools (it is assumed that the context
125      * already wraps the global context, and thus already contains
126      * the global tools).
127      *
128      * @param context a Velocity Context to populate
129      * @param data a RunData object for request specific data
130      */
131      void populateContext(Context context, RunData data);
132
133    /**
134     * Return the absolute path of the resources directory
135     * used by application tools.
136     *
137     * @return A directory path in the file system or null.
138     */
139    String getAbsolutePathToResourcesDirectory();
140
141    /**
142     * Return the resources directory. This is relative
143     * to the webapp context.
144     *
145     * @return A directory path to the resources directory relative to the webapp root or null.
146     */
147    String getResourcesDirectory();
148
149    /**
150     * Release tool instances from the given context to the
151     * object pool
152     *
153     * @param context a Velocity Context to release tools from
154     */
155    void releaseTools(Context context);
156}