server/filter/PluginFilterManager.java

//---PACKAGE DECLARATION---
package uk.org.iscream.cms.server.filter;

//---IMPORTS---
import java.io.*;
import java.util.*;

import uk.org.iscream.cms.server.util.*;
import uk.org.iscream.cms.server.componentmanager.*;
import uk.org.iscream.cms.server.core.*;

/**
 * This class setups up and manages Plugins in a Filter. A list
 * of plugins to use is specified in the configuration, and these
 * are all loaded upon first use of this class.
 * This is a singleton class.
 *
 * @author  $Author: tdb1 $
 * @version $Id: PluginFilterManager.java,v 1.8 2001/03/14 23:25:29 tdb1 Exp $
 */
class PluginFilterManager {

//---FINAL ATTRIBUTES---

    /**
     * The current CVS revision of this class
     */
    public final String REVISION = "$Revision: 1.8 $";
    
//---STATIC METHODS---

    /**
     * Return a reference to the single class.
     * Construct it if it does not already exist, otherwise just return the reference.
     */
    public static PluginFilterManager getInstance() {
        if (_instance == null){
            _instance = new PluginFilterManager();
        }
        return _instance;
    }

//---CONSTRUCTORS---

    /**
     * Private Constructor - this part creates the filter pipeline
     * This is a singleton class, btw.
     */
    private PluginFilterManager(){
        
        _logger.write(toString(), Logger.SYSINIT, "Initialising");
        _logger.write(toString(), Logger.SYSMSG, "Creating filter pipeline for plugin filters ...");
        
        String pluginsPackage, pluginsList;
        
        try {
            // get the configuration for this plug-in setup
            ConfigurationProxy cp = ConfigurationProxy.getInstance();
            pluginsPackage = cp.getProperty(FilterMain.NAME, "Filter.PluginsPackage");
            pluginsList = cp.getProperty(FilterMain.NAME, "Filter.Plugins");
        } catch (PropertyNotFoundException e) {
            _logger.write(toString(), Logger.WARNING, "Unable to locate property: "+e);
            // setting this to "" will avoid building a plugin list,
            // which is what we want when a property doesn't exist
            pluginsList = "";
            // and set this to "", because the compiler is a git
            pluginsPackage = "";
        }
        
        StringTokenizer st = new StringTokenizer(pluginsList, ";");
        
        while(st.hasMoreTokens()) {
            String className = pluginsPackage + "." + st.nextToken() + _suffix;
            _logger.write(toString(), Logger.DEBUG, "Attempting to create plugin: "+className);
            
            // Create an instance of the specified PluginFilter to include
            // within the filterPipe.  Add it to the filterPipeline
            try {
                PluginFilter pf = (PluginFilter)ClassLoader.getSystemClassLoader().loadClass(className).newInstance();
                _filterPipeline.add(pf);
                _logger.write(toString(), Logger.DEBUG, "Added filter: "+className+" ("+pf.getDescription()+")");
            }
            catch (InstantiationException e){
                _logger.write(toString(), Logger.ERROR, "Failed to instantiate "+className+" to the plugin filter pipeline.");
                _logger.write(toString(), Logger.ERROR, e.getMessage());
            }
            catch (Exception e){
                _logger.write(toString(), Logger.ERROR, "Failed to add "+className+" to the plugin filter pipeline.");
                _logger.write(toString(), Logger.ERROR, e.toString());
            }
        }
        _logger.write(toString(), Logger.SYSMSG, "The filter pipeline has been set up with "+_filterPipeline.size()+" plugin filters.");
        
    }

//---PUBLIC METHODS---

    /**
     * apply all of the filters in the pipeline to the packet.
     * return true if they all accept the packet.
     * return false if any single filter rejects the packet.
     * return true if there are no filters inthe pipeline.
     *
     * @param packet an XMLPacket to be tested
     * @return whether the packet can be passed on
     */
    public boolean runFilters(XMLPacket packet){
        
        // for each filter in the pipeline...
        ListIterator pluginFilters = _filterPipeline.listIterator(0);
        while (pluginFilters.hasNext()){
            PluginFilter filter = (PluginFilter)pluginFilters.next();
            if (!filter.runFilter(packet)){
                return false;
            }
        }
        
        return true;
    }

    /**
     * Overrides the {@link java.lang.Object#toString() Object.toString()}
     * method to provide clean logging (every class should have this).
     *
     * This uses the uk.org.iscream.cms.server.util.NameFormat class
     * to format the toString()
     *
     * @return the name of this class and its CVS revision
     */
    public String toString() {
        return FormatName.getName(
            _name,
            getClass().getName(),
            REVISION);
    }

//---PRIVATE METHODS---

//---ACCESSOR/MUTATOR METHODS---

//---ATTRIBUTES---
   
    /**
     * file name suffix for plugin filter classes:
     */
    private final String _suffix = "__Plugin";
    
    /**
     * LinkedList for holding the PluginFilter objects (the pipeline).
     */
    private LinkedList _filterPipeline = new LinkedList();
    
    /**
     * A reference to the single instance of this class
     */
    private static PluginFilterManager _instance;

    /**
     * This is the friendly identifier of the
     * component this class is running in.
     * eg, a Filter may be called "filter1",
     * If this class does not have an owning
     * component,  a name from the configuration
     * can be placed here.  This name could also
     * be changed to null for utility classes.
     */
    private String _name = FilterMain.NAME;

    /**
     * This holds a reference to the
     * system logger that is being used.
     */
    private Logger _logger = ReferenceManager.getInstance().getLogger();
    
    /**
     * A reference to the reference manager in use
     */
    private ReferenceManager _refman = ReferenceManager.getInstance();

//---STATIC ATTRIBUTES---

}
Revision:	1.9
Committed:	Tue May 29 17:02:35 2001 UTC (22 years, 11 months ago) by tdb
Branch:	MAIN
Branch point for:	SERVER_PIRCBOT
Changes since 1.8:	+7 -7 lines
Log Message:	Major change in the java package naming. This has been held off for some time now, but it really needed doing. The future packaging of all i-scream products will be; uk.org.iscream.<product>.<subpart>.* In the case of the central monitoring system server this will be; uk.org.iscream.cms.server.* The whole server has been changed to follow this structure, and tested to a smallish extent. Further changes in other parts of the CMS will follow.
#	Content
1	//---PACKAGE DECLARATION---
2	package uk.org.iscream.cms.server.filter;
3
4	//---IMPORTS---
5	import java.io.*;
6	import java.util.*;
7
8	import uk.org.iscream.cms.server.util.*;
9	import uk.org.iscream.cms.server.componentmanager.*;
10	import uk.org.iscream.cms.server.core.*;
11
12	/**
13	* This class setups up and manages Plugins in a Filter. A list
14	* of plugins to use is specified in the configuration, and these
15	* are all loaded upon first use of this class.
16	* This is a singleton class.
17	*
18	* @author $Author: tdb1 $
19	* @version $Id: PluginFilterManager.java,v 1.8 2001/03/14 23:25:29 tdb1 Exp $
20	*/
21	class PluginFilterManager {
22
23	//---FINAL ATTRIBUTES---
24
25	/**
26	* The current CVS revision of this class
27	*/
28	public final String REVISION = "$Revision: 1.8 $";
29
30	//---STATIC METHODS---
31
32	/**
33	* Return a reference to the single class.
34	* Construct it if it does not already exist, otherwise just return the reference.
35	*/
36	public static PluginFilterManager getInstance() {
37	if (_instance == null){
38	_instance = new PluginFilterManager();
39	}
40	return _instance;
41	}
42
43	//---CONSTRUCTORS---
44
45	/**
46	* Private Constructor - this part creates the filter pipeline
47	* This is a singleton class, btw.
48	*/
49	private PluginFilterManager(){
50
51	_logger.write(toString(), Logger.SYSINIT, "Initialising");
52	_logger.write(toString(), Logger.SYSMSG, "Creating filter pipeline for plugin filters ...");
53
54	String pluginsPackage, pluginsList;
55
56	try {
57	// get the configuration for this plug-in setup
58	ConfigurationProxy cp = ConfigurationProxy.getInstance();
59	pluginsPackage = cp.getProperty(FilterMain.NAME, "Filter.PluginsPackage");
60	pluginsList = cp.getProperty(FilterMain.NAME, "Filter.Plugins");
61	} catch (PropertyNotFoundException e) {
62	_logger.write(toString(), Logger.WARNING, "Unable to locate property: "+e);
63	// setting this to "" will avoid building a plugin list,
64	// which is what we want when a property doesn't exist
65	pluginsList = "";
66	// and set this to "", because the compiler is a git
67	pluginsPackage = "";
68	}
69
70	StringTokenizer st = new StringTokenizer(pluginsList, ";");
71
72	while(st.hasMoreTokens()) {
73	String className = pluginsPackage + "." + st.nextToken() + _suffix;
74	_logger.write(toString(), Logger.DEBUG, "Attempting to create plugin: "+className);
75
76	// Create an instance of the specified PluginFilter to include
77	// within the filterPipe. Add it to the filterPipeline
78	try {
79	PluginFilter pf = (PluginFilter)ClassLoader.getSystemClassLoader().loadClass(className).newInstance();
80	_filterPipeline.add(pf);
81	_logger.write(toString(), Logger.DEBUG, "Added filter: "+className+" ("+pf.getDescription()+")");
82	}
83	catch (InstantiationException e){
84	_logger.write(toString(), Logger.ERROR, "Failed to instantiate "+className+" to the plugin filter pipeline.");
85	_logger.write(toString(), Logger.ERROR, e.getMessage());
86	}
87	catch (Exception e){
88	_logger.write(toString(), Logger.ERROR, "Failed to add "+className+" to the plugin filter pipeline.");
89	_logger.write(toString(), Logger.ERROR, e.toString());
90	}
91	}
92	_logger.write(toString(), Logger.SYSMSG, "The filter pipeline has been set up with "+_filterPipeline.size()+" plugin filters.");
93
94	}
95
96	//---PUBLIC METHODS---
97
98	/**
99	* apply all of the filters in the pipeline to the packet.
100	* return true if they all accept the packet.
101	* return false if any single filter rejects the packet.
102	* return true if there are no filters inthe pipeline.
103	*
104	* @param packet an XMLPacket to be tested
105	* @return whether the packet can be passed on
106	*/
107	public boolean runFilters(XMLPacket packet){
108
109	// for each filter in the pipeline...
110	ListIterator pluginFilters = _filterPipeline.listIterator(0);
111	while (pluginFilters.hasNext()){
112	PluginFilter filter = (PluginFilter)pluginFilters.next();
113	if (!filter.runFilter(packet)){
114	return false;
115	}
116	}
117
118	return true;
119	}
120
121	/**
122	* Overrides the {@link java.lang.Object#toString() Object.toString()}
123	* method to provide clean logging (every class should have this).
124	*
125	* This uses the uk.org.iscream.cms.server.util.NameFormat class
126	* to format the toString()
127	*
128	* @return the name of this class and its CVS revision
129	*/
130	public String toString() {
131	return FormatName.getName(
132	_name,
133	getClass().getName(),
134	REVISION);
135	}
136
137	//---PRIVATE METHODS---
138
139	//---ACCESSOR/MUTATOR METHODS---
140
141	//---ATTRIBUTES---
142
143	/**
144	* file name suffix for plugin filter classes:
145	*/
146	private final String _suffix = "__Plugin";
147
148	/**
149	* LinkedList for holding the PluginFilter objects (the pipeline).
150	*/
151	private LinkedList _filterPipeline = new LinkedList();
152
153	/**
154	* A reference to the single instance of this class
155	*/
156	private static PluginFilterManager _instance;
157
158	/**
159	* This is the friendly identifier of the
160	* component this class is running in.
161	* eg, a Filter may be called "filter1",
162	* If this class does not have an owning
163	* component, a name from the configuration
164	* can be placed here. This name could also
165	* be changed to null for utility classes.
166	*/
167	private String _name = FilterMain.NAME;
168
169	/**
170	* This holds a reference to the
171	* system logger that is being used.
172	*/
173	private Logger _logger = ReferenceManager.getInstance().getLogger();
174
175	/**
176	* A reference to the reference manager in use
177	*/
178	private ReferenceManager _refman = ReferenceManager.getInstance();
179
180	//---STATIC ATTRIBUTES---
181
182	}