server/filter/PluginServiceCheckManager.java

//---PACKAGE DECLARATION---
package uk.ac.ukc.iscream.filter;

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

import uk.ac.ukc.iscream.util.*;
import uk.ac.ukc.iscream.componentmanager.*;
import uk.ac.ukc.iscream.core.*;

/**
 * This class setups up and manages Plugins for performing service
 * checks.  When asked to run some service checks it runs the checks
 * on the service check pipeline for that host.  If the pipleline does
 * not exist it creates a new one.
 *
 * This is a singleton class.
 *
 * ###
 * This does not fully manage the pipelines, it should check
 * if a host has not heartbeated for a while and thus remove 
 * the pipeline.  At the moment it does not.
 * A suggestions for doing this is to use the getCreated() 
 * method on the PluginServiceCheckPipeline.  This tells you when
 * according to the system time the pipeline was created.  You could
 * then have a thread that periodically checks to see if a host
 * has not run its pipeline in say two heartbeats, and thus
 * this indicates that it is no longer running.  The pipeline
 * could then be removed from the hashmap and thus be eligable
 * for gc.
 * ###
 *
 * @author  $Author: tdb1 $
 * @version $Id: PluginFilterManager.java,v 1.6 2001/02/01 00:18:42 tdb1 Exp $
 */
class PluginServiceCheckManager {

//---FINAL ATTRIBUTES---

    /**
     * The current CVS revision of this class
     */
    public final String REVISION = "$Revision: 1.6 $";
    
    /**
     * file name suffix for plugin filter classes:
     */
    private final String _suffix = "__ServiceCheck";
    
//---STATIC METHODS---

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

//---CONSTRUCTORS---

    /**
     * Private Constructor - this part creates the filter pipeline
     * This is a singleton class, btw.
     */
    private PluginServiceCheckManager(){
        _logger.write(toString(), Logger.SYSINIT, "created");
    }

//---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 the host to run service checks for
     * @return whether the packet can be passed on
     */
    public String runServiceChecks(String hostname){
        if (!_hostPipelines.containsKey(hostname)) {
               _hostPipelines.put(hostname, new PluginServiceCheckPipeline(hostname, this));
        }
        return "<services>" + ((PluginServiceCheckPipeline) _hostPipelines.get(hostname)).runPipeline() + "</services>";
    }

    /**
     * Overrides the {@link java.lang.Object#toString() Object.toString()}
     * method to provide clean logging (every class should have this).
     *
     * This uses the uk.ac.ukc.iscream.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---

    /**
     * Returns a reference to the specified service check.
     * This method takes the name of the class that contains
     * a service check implementation.  It then checks to see
     * if it has loaded that class before.  If it has it returns
     * a reference to it, if not, it loads it for the first time,
     * remembers it, then returns that.
     *
     * @param className the PluginServiceCheck to be loaded
     * @return the requested PluginServiceCheck
     */
    public synchronized PluginServiceCheck getServiceCheck(String className) {
        // see if we've already got the service check loaded
        if(_loadedServiceChecks.containsKey(className)) {
            _logger.write(toString(), Logger.DEBUG, className + " already loaded - returning reference to it.");
            return (PluginServiceCheck) _loadedServiceChecks.get(className);
        }
        // otherwise we need to load it and return
        _logger.write(toString(), Logger.DEBUG, "attempting to load service check - " + className);
        
        // Create an instance of the specified PluginServiceCheck
        // then added it to the list of already loaded service checks
        PluginServiceCheck serviceCheck = null;
        try {
            serviceCheck = (PluginServiceCheck)ClassLoader.getSystemClassLoader().loadClass(className).newInstance();
            _loadedServiceChecks.put(className, serviceCheck);
            _logger.write(toString(), Logger.DEBUG, "loaded service check - "+className+" ("+serviceCheck.getDescription()+")");
        }
        catch (InstantiationException e){
            _logger.write(toString(), Logger.ERROR, "failed to instantiate - "+className);
            _logger.write(toString(), Logger.ERROR, e.getMessage());
        }
        catch (Exception e){
            _logger.write(toString(), Logger.ERROR, "failed to add - "+className);
            _logger.write(toString(), Logger.ERROR, e.toString());
        }
        
        return serviceCheck;
    }

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

//---ATTRIBUTES---
 
    /**
     * A hash map containing host pipelines
     */
    private HashMap _hostPipelines = new HashMap();
 
    /**
     * A hash map containing host pipelines
     */
    private HashMap _loadedServiceChecks = new HashMap();
 
    /**
     * 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---

    /**
     * A reference to the single instance of this class
     */
    private static PluginServiceCheckManager _instance;
}
Revision:	1.2
Committed:	Sun Feb 11 18:11:05 2001 UTC (23 years, 3 months ago) by ajm
Branch:	MAIN
Changes since 1.1:	+4 -4 lines
Log Message:	code typos fixed.
#	Content
1	//---PACKAGE DECLARATION---
2	package uk.ac.ukc.iscream.filter;
3
4	//---IMPORTS---
5	import java.io.*;
6	import java.util.*;
7
8	import uk.ac.ukc.iscream.util.*;
9	import uk.ac.ukc.iscream.componentmanager.*;
10	import uk.ac.ukc.iscream.core.*;
11
12	/**
13	* This class setups up and manages Plugins for performing service
14	* checks. When asked to run some service checks it runs the checks
15	* on the service check pipeline for that host. If the pipleline does
16	* not exist it creates a new one.
17	*
18	* This is a singleton class.
19	*
20	* ###
21	* This does not fully manage the pipelines, it should check
22	* if a host has not heartbeated for a while and thus remove
23	* the pipeline. At the moment it does not.
24	* A suggestions for doing this is to use the getCreated()
25	* method on the PluginServiceCheckPipeline. This tells you when
26	* according to the system time the pipeline was created. You could
27	* then have a thread that periodically checks to see if a host
28	* has not run its pipeline in say two heartbeats, and thus
29	* this indicates that it is no longer running. The pipeline
30	* could then be removed from the hashmap and thus be eligable
31	* for gc.
32	* ###
33	*
34	* @author $Author: tdb1 $
35	* @version $Id: PluginFilterManager.java,v 1.6 2001/02/01 00:18:42 tdb1 Exp $
36	*/
37	class PluginServiceCheckManager {
38
39	//---FINAL ATTRIBUTES---
40
41	/**
42	* The current CVS revision of this class
43	*/
44	public final String REVISION = "$Revision: 1.6 $";
45
46	/**
47	* file name suffix for plugin filter classes:
48	*/
49	private final String _suffix = "__ServiceCheck";
50
51	//---STATIC METHODS---
52
53	/**
54	* Return a reference to the single class.
55	* Construct it if it does not already exist, otherwise just return the reference.
56	*/
57	public static PluginServiceCheckManager getInstance() {
58	if (_instance == null){
59	_instance = new PluginServiceCheckManager();
60	}
61	return _instance;
62	}
63
64	//---CONSTRUCTORS---
65
66	/**
67	* Private Constructor - this part creates the filter pipeline
68	* This is a singleton class, btw.
69	*/
70	private PluginServiceCheckManager(){
71	_logger.write(toString(), Logger.SYSINIT, "created");
72	}
73
74	//---PUBLIC METHODS---
75
76	/**
77	* apply all of the filters in the pipeline to the packet.
78	* return true if they all accept the packet.
79	* return false if any single filter rejects the packet.
80	* return true if there are no filters inthe pipeline.
81	*
82	* @param the host to run service checks for
83	* @return whether the packet can be passed on
84	*/
85	public String runServiceChecks(String hostname){
86	if (!_hostPipelines.containsKey(hostname)) {
87	_hostPipelines.put(hostname, new PluginServiceCheckPipeline(hostname, this));
88	}
89	return "<services>" + ((PluginServiceCheckPipeline) _hostPipelines.get(hostname)).runPipeline() + "</services>";
90	}
91
92	/**
93	* Overrides the {@link java.lang.Object#toString() Object.toString()}
94	* method to provide clean logging (every class should have this).
95	*
96	* This uses the uk.ac.ukc.iscream.util.NameFormat class
97	* to format the toString()
98	*
99	* @return the name of this class and its CVS revision
100	*/
101	public String toString() {
102	return FormatName.getName(
103	_name,
104	getClass().getName(),
105	REVISION);
106	}
107
108	//---PRIVATE METHODS---
109
110	/**
111	* Returns a reference to the specified service check.
112	* This method takes the name of the class that contains
113	* a service check implementation. It then checks to see
114	* if it has loaded that class before. If it has it returns
115	* a reference to it, if not, it loads it for the first time,
116	* remembers it, then returns that.
117	*
118	* @param className the PluginServiceCheck to be loaded
119	* @return the requested PluginServiceCheck
120	*/
121	public synchronized PluginServiceCheck getServiceCheck(String className) {
122	// see if we've already got the service check loaded
123	if(_loadedServiceChecks.containsKey(className)) {
124	_logger.write(toString(), Logger.DEBUG, className + " already loaded - returning reference to it.");
125	return (PluginServiceCheck) _loadedServiceChecks.get(className);
126	}
127	// otherwise we need to load it and return
128	_logger.write(toString(), Logger.DEBUG, "attempting to load service check - " + className);
129
130	// Create an instance of the specified PluginServiceCheck
131	// then added it to the list of already loaded service checks
132	PluginServiceCheck serviceCheck = null;
133	try {
134	serviceCheck = (PluginServiceCheck)ClassLoader.getSystemClassLoader().loadClass(className).newInstance();
135	_loadedServiceChecks.put(className, serviceCheck);
136	_logger.write(toString(), Logger.DEBUG, "loaded service check - "+className+" ("+serviceCheck.getDescription()+")");
137	}
138	catch (InstantiationException e){
139	_logger.write(toString(), Logger.ERROR, "failed to instantiate - "+className);
140	_logger.write(toString(), Logger.ERROR, e.getMessage());
141	}
142	catch (Exception e){
143	_logger.write(toString(), Logger.ERROR, "failed to add - "+className);
144	_logger.write(toString(), Logger.ERROR, e.toString());
145	}
146
147	return serviceCheck;
148	}
149
150	//---ACCESSOR/MUTATOR METHODS---
151
152	//---ATTRIBUTES---
153
154	/**
155	* A hash map containing host pipelines
156	*/
157	private HashMap _hostPipelines = new HashMap();
158
159	/**
160	* A hash map containing host pipelines
161	*/
162	private HashMap _loadedServiceChecks = new HashMap();
163
164	/**
165	* This is the friendly identifier of the
166	* component this class is running in.
167	* eg, a Filter may be called "filter1",
168	* If this class does not have an owning
169	* component, a name from the configuration
170	* can be placed here. This name could also
171	* be changed to null for utility classes.
172	*/
173	private String _name = FilterMain.NAME;
174
175	/**
176	* This holds a reference to the
177	* system logger that is being used.
178	*/
179	private Logger _logger = ReferenceManager.getInstance().getLogger();
180
181	/**
182	* A reference to the reference manager in use
183	*/
184	private ReferenceManager _refman = ReferenceManager.getInstance();
185
186	//---STATIC ATTRIBUTES---
187
188	/**
189	* A reference to the single instance of this class
190	*/
191	private static PluginServiceCheckManager _instance;
192	}