server/core/ConfigurationManagerServant.java

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

//---IMPORTS---
import uk.ac.ukc.iscream.util.*;
import uk.ac.ukc.iscream.componentmanager.*;
import java.util.*;
import java.io.*;

/**
 * This class is essentially a Configuration factory.
 * This class implements the Configurator IDL and allows
 * other classes in the system ot obtain their Configuration
 *
 * On construction it requires a reference to the RootPOA
 * to allow it to create Configuration objects to be
 * returned.
 *
 * It also relies on the System.properties to set internal values.
 *
 * ###
 * A point to note is that this class does NOT yet manage
 * created configurations which may cause memory problems!
 * ###
 *
 * @author  $Author: ajm4 $
 * @version $Id: ConfigurationManagerServant.java,v 1.6 2000/12/12 18:26:52 ajm4 Exp $
 */
class ConfigurationManagerServant extends ConfigurationManagerPOA {

//---FINAL ATTRIBUTES---

    /**
     * The current CVS revision of this class
     */
    public final String REVISION = "$Revision: 1.6 $";
    
//---STATIC METHODS---

//---CONSTRUCTORS---

    /**
     * Creates a new ConfiguratorServant
     * This class uses the System.properties to set internal values
     */
    ConfigurationManagerServant() {
        // assign some local variables
        _configPath = System.getProperty("uk.ac.ukc.iscream.ConfigurationLocation");
        _systemConfigFile = System.getProperty("uk.ac.ukc.iscream.SystemConfigurationFile");

        // load the system config
        loadSystemConfig();

        // log our status
        _logger.write(toString(), Logger.SYSINIT, "started");
        _logger.write(toString(), Logger.SYSMSG, "configuration location - " + _configPath);
        _logger.write(toString(), Logger.SYSMSG, "system configuration file - " + _systemConfigFile);
    }

//---PUBLIC METHODS---
    
    /**
     * Returns a Configuration object which contains
     * the configuration data requested by the calling
     * object.
     *
     * This method will look in the systemConfig file
     * for an entry for this "source", if there is no
     * entry it returns a refernce to the system
     * config.  If there are any errors in reading the 
     * configuration, it returns null, the caller is 
     * expected to be able to handle this.
     *
     * This method also checks to see if the system.conf
     * file has been updated and reloads its reference if
     * needed.
     *
     * @param source the configuration required
     * @return the Configuration
     */
    public Configuration getConfiguration(String source) {
        _logger.write(toString(), Logger.SYSMSG, "got request for " + source);
        Configuration config = null;
        
        // check to see if we need to reload the system config
        // because it has changed
        if (isModified(_systemConfig.getFileList(), _systemConfig.getLastModified())) {
            _logger.write(toString(), Logger.SYSMSG, "system config changed");
            loadSystemConfig();
        }

        // we look for this entry in the systemConfig
        String configFile = _systemConfig.getProperty("config." + source);
        _logger.write(toString(), Logger.DEBUG, "looking for config tree in - " + configFile);

        // if there is an entry
        if (configFile != null) {
            try {
                // get the file list of includes etc + the system config
                String fileList = _systemConfigFile + ";" + getIncludedFiles(configFile, "");            
                _logger.write(toString(), Logger.DEBUG, "config tree - " + fileList);
                
                // build the properites here from the filelist.... 
                StringTokenizer st = new StringTokenizer(fileList, ";");
                
                // some holders for variables
                File currentFile;
                long lastModified, newLastModified;
                Properties properties, prevProperties;
                
                // the root of all configurations will be the system config
                // so we need to open the properties of that
                Properties defaultProperties = new Properties();
                currentFile = new File(_configPath, _systemConfigFile);
                lastModified = currentFile.lastModified();
                defaultProperties.load(new FileInputStream(currentFile));
                
                // This loop then iterates over the file list
                // creates the properties to be passed to the
                // Configuration constructor
                do {
                    properties = new Properties(defaultProperties);
                    currentFile = new File(_configPath, st.nextToken());
                    newLastModified = currentFile.lastModified();
                    if (newLastModified > lastModified) {
                        lastModified = newLastModified;
                    }
                    properties.load(new FileInputStream(currentFile));
                    defaultProperties = properties;
                } while (st.hasMoreTokens());

                // this creates the configuration, all nice, ready to be returned
                ConfigurationServant ref = new ConfigurationServant(properties, fileList, lastModified);
                org.omg.CORBA.Object objRef = _refman.getRootPOA().servant_to_reference(ref);
                config = ConfigurationHelper.narrow(objRef);

            } catch (Exception e) {
                // not sure what to do here
                // so we just log the error
                _logger.write(toString(), Logger.ERROR, "ERROR - " + e.getMessage());
            }
            
        // if there isn't an entry for the requested config
        } else {
            _logger.write(toString(), Logger.DEBUG, "no configured config, returning " + _systemConfigFile);
            config = _systemConfig;
        }
        
        // if this is null at this point, then there will have been an error
        return config;
    }
    
    
    /**
     * When passed a file list and a current value for the lastModified
     * of the current configuration, this method compares the value
     * to the actual value of the configuration files to determine 
     * whether or not the configuration has been modified.
     *
     * @param fileList a list of files that the caller uses for configuration
     * @param lastModified the last modified date of the callers configuration
     *
     * @return whether or not the configuration has been modified
     */
    public boolean isModified(String fileList, long lastModified) {
        StringTokenizer st = new StringTokenizer(fileList, ";");
        long newLastModified;
        File currentFile;
        while (st.hasMoreTokens()) {
            currentFile = new File(_configPath, st.nextToken());
            newLastModified = currentFile.lastModified();
            if (newLastModified > lastModified) {
                return true;
            }
        }
        return false;
    }

    /**
     * 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.FormatName 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---

    /**
     * This is a recursive function private to this class.
     * It constructs a hierarchy of files as a ";" serperated
     * string which can be used to read in the configuration.
     * This function calls itself.
     * 
     * @param currentFile the current file to be processed
     * @param readFiles used for recursion purposes only, these are the files it has read so far 
     *
     * @return the current list that has been constructed
     *
     * @throws IOException if there is trouble reading the file
     * @throws FileNotFoundException is there is trouble finding the file
     * @throws CircularIncludeException this is if a circular include is detected
     */
    private String getIncludedFiles(String currentFile, String readFiles) throws IOException, FileNotFoundException, Exception {
        
        // check for circular include here
        if (hasDuplicate(currentFile, readFiles) || currentFile.equals(_systemConfigFile)) {
            throw new CircularIncludeException(currentFile + " is included more than once");
        }
        
        // if there wasn't, we're gonna use this file, so make a note of it as read
        // (note the use of the ";", this is for the hasDuplicate, function)
        readFiles = readFiles + currentFile + ";";

        Properties properties = new Properties();
        properties.load(new FileInputStream(new File(_configPath, currentFile)));
        
        // get the include property
        String includes = properties.getProperty("include");

        // if we're the last file with no includes, return our name
        if (includes == null) {
            return currentFile;
        
        // otherwise, recurse over our includes
        } else {
            StringTokenizer st = new StringTokenizer(includes, ";");
            String returnList= "";
            while (st.hasMoreTokens()) {
                returnList = getIncludedFiles(st.nextToken(), readFiles) + ";" + returnList;
            }
            
            return returnList + currentFile;
        }
    }

    /**
     * This simple method checks to see if a given 
     * file exists in the given list.
     *
     * @param file the file to check the list for
     * @param fileList the list to check
     *
     * @return if the given file appeard in the list
     */
    private boolean hasDuplicate(String file, String fileList) {
        StringTokenizer st = new StringTokenizer(fileList, ";");
        while (st.hasMoreTokens()) {
            if (file.equals(st.nextToken())) {
                return true;
            }
        }
        return false;
    }

    /**
     * Opens and loads the system configuration into the 
     * local reference _systemConfig
     */
    private void loadSystemConfig() {
        _logger.write(this.toString(), Logger.SYSMSG, "reloading " + _systemConfigFile);
        // get a reference to the system config and store it
        try {
            // create the properties for the configuration
            File systemConfigFile = new File(_configPath, _systemConfigFile);
            Properties systemConfigHolder = new Properties();
            systemConfigHolder.load(new FileInputStream(systemConfigFile));
                        
            // create the servant
            ConfigurationServant ref = new ConfigurationServant(systemConfigHolder, _systemConfigFile, systemConfigFile.lastModified());
            org.omg.CORBA.Object objRef = _refman.getRootPOA().servant_to_reference(ref);
            
            // narrow it to a Configuration
            _systemConfig = ConfigurationHelper.narrow(objRef);
            
        } catch (Exception e) {
            _logger.write(toString(), Logger.FATAL, "ERROR: " + e.getMessage());
        }
    }

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

//---ATTRIBUTES---

    /**
     * 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 = Core.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();
    
    /**
     * The root path to all configurations
     */
    private String _configPath;
    
    /**
     * The name of the file that contains the system configuration
     */
    private String _systemConfigFile;
    
    /**
     * An instance of the system config
     */
    private Configuration _systemConfig;
    
//---STATIC ATTRIBUTES---
    
}
Revision:	1.7
Committed:	Thu Jan 18 23:10:44 2001 UTC (23 years, 4 months ago) by tdb
Branch:	MAIN
Changes since 1.6:	+3 -2 lines
Log Message:	Changes to reflect move of Component, ComponentStartException, and the ReferenceManager from util to componentmanager.
#	User	Rev	Content
1	ajm	1.3	//---PACKAGE DECLARATION---
2	ajm	1.5	package uk.ac.ukc.iscream.core;
3	ajm	1.3
4			//---IMPORTS---
5	ajm	1.6	import uk.ac.ukc.iscream.util.*;
6	tdb	1.7	import uk.ac.ukc.iscream.componentmanager.*;
7	ajm	1.3	import java.util.*;
8			import java.io.*;
9
10			/**
11			* This class is essentially a Configuration factory.
12			* This class implements the Configurator IDL and allows
13			* other classes in the system ot obtain their Configuration
14			*
15			* On construction it requires a reference to the RootPOA
16			* to allow it to create Configuration objects to be
17			* returned.
18			*
19			* It also relies on the System.properties to set internal values.
20			*
21	ajm	1.6	* ###
22			* A point to note is that this class does NOT yet manage
23			* created configurations which may cause memory problems!
24			* ###
25			*
26	ajm	1.4	* @author $Author: ajm4 $
27	tdb	1.7	* @version $Id: ConfigurationManagerServant.java,v 1.6 2000/12/12 18:26:52 ajm4 Exp $
28	ajm	1.3	*/
29			class ConfigurationManagerServant extends ConfigurationManagerPOA {
30
31			//---FINAL ATTRIBUTES---
32
33			/**
34			* The current CVS revision of this class
35			*/
36	tdb	1.7	public final String REVISION = "$Revision: 1.6 $";
37	ajm	1.3
38			//---STATIC METHODS---
39
40			//---CONSTRUCTORS---
41
42			/**
43			* Creates a new ConfiguratorServant
44			* This class uses the System.properties to set internal values
45			*/
46	ajm	1.6	ConfigurationManagerServant() {
47	ajm	1.3	// assign some local variables
48			_configPath = System.getProperty("uk.ac.ukc.iscream.ConfigurationLocation");
49			_systemConfigFile = System.getProperty("uk.ac.ukc.iscream.SystemConfigurationFile");
50
51			// load the system config
52			loadSystemConfig();
53
54			// log our status
55	ajm	1.6	_logger.write(toString(), Logger.SYSINIT, "started");
56			_logger.write(toString(), Logger.SYSMSG, "configuration location - " + _configPath);
57			_logger.write(toString(), Logger.SYSMSG, "system configuration file - " + _systemConfigFile);
58	ajm	1.3	}
59
60			//---PUBLIC METHODS---
61
62			/**
63			* Returns a Configuration object which contains
64			* the configuration data requested by the calling
65			* object.
66			*
67			* This method will look in the systemConfig file
68			* for an entry for this "source", if there is no
69			* entry it returns a refernce to the system
70			* config. If there are any errors in reading the
71			* configuration, it returns null, the caller is
72			* expected to be able to handle this.
73			*
74			* This method also checks to see if the system.conf
75			* file has been updated and reloads its reference if
76			* needed.
77			*
78			* @param source the configuration required
79			* @return the Configuration
80			*/
81			public Configuration getConfiguration(String source) {
82	ajm	1.6	_logger.write(toString(), Logger.SYSMSG, "got request for " + source);
83	ajm	1.3	Configuration config = null;
84
85			// check to see if we need to reload the system config
86			// because it has changed
87			if (isModified(_systemConfig.getFileList(), _systemConfig.getLastModified())) {
88	ajm	1.6	_logger.write(toString(), Logger.SYSMSG, "system config changed");
89	ajm	1.3	loadSystemConfig();
90			}
91
92			// we look for this entry in the systemConfig
93			String configFile = _systemConfig.getProperty("config." + source);
94	ajm	1.6	_logger.write(toString(), Logger.DEBUG, "looking for config tree in - " + configFile);
95	ajm	1.3
96			// if there is an entry
97			if (configFile != null) {
98			try {
99	ajm	1.4	// get the file list of includes etc + the system config
100			String fileList = _systemConfigFile + ";" + getIncludedFiles(configFile, "");
101	ajm	1.6	_logger.write(toString(), Logger.DEBUG, "config tree - " + fileList);
102	ajm	1.3
103			// build the properites here from the filelist....
104			StringTokenizer st = new StringTokenizer(fileList, ";");
105
106			// some holders for variables
107			File currentFile;
108			long lastModified, newLastModified;
109			Properties properties, prevProperties;
110
111			// the root of all configurations will be the system config
112			// so we need to open the properties of that
113			Properties defaultProperties = new Properties();
114			currentFile = new File(_configPath, _systemConfigFile);
115			lastModified = currentFile.lastModified();
116			defaultProperties.load(new FileInputStream(currentFile));
117
118			// This loop then iterates over the file list
119			// creates the properties to be passed to the
120			// Configuration constructor
121			do {
122			properties = new Properties(defaultProperties);
123			currentFile = new File(_configPath, st.nextToken());
124			newLastModified = currentFile.lastModified();
125			if (newLastModified > lastModified) {
126			lastModified = newLastModified;
127			}
128			properties.load(new FileInputStream(currentFile));
129			defaultProperties = properties;
130			} while (st.hasMoreTokens());
131
132			// this creates the configuration, all nice, ready to be returned
133	ajm	1.6	ConfigurationServant ref = new ConfigurationServant(properties, fileList, lastModified);
134			org.omg.CORBA.Object objRef = _refman.getRootPOA().servant_to_reference(ref);
135	ajm	1.3	config = ConfigurationHelper.narrow(objRef);
136
137			} catch (Exception e) {
138			// not sure what to do here
139	ajm	1.6	// so we just log the error
140			_logger.write(toString(), Logger.ERROR, "ERROR - " + e.getMessage());
141	ajm	1.3	}
142
143	ajm	1.4	// if there isn't an entry for the requested config
144	ajm	1.3	} else {
145	ajm	1.6	_logger.write(toString(), Logger.DEBUG, "no configured config, returning " + _systemConfigFile);
146	ajm	1.3	config = _systemConfig;
147			}
148
149			// if this is null at this point, then there will have been an error
150			return config;
151			}
152
153
154			/**
155			* When passed a file list and a current value for the lastModified
156			* of the current configuration, this method compares the value
157			* to the actual value of the configuration files to determine
158			* whether or not the configuration has been modified.
159			*
160			* @param fileList a list of files that the caller uses for configuration
161			* @param lastModified the last modified date of the callers configuration
162			*
163			* @return whether or not the configuration has been modified
164			*/
165			public boolean isModified(String fileList, long lastModified) {
166			StringTokenizer st = new StringTokenizer(fileList, ";");
167			long newLastModified;
168			File currentFile;
169			while (st.hasMoreTokens()) {
170			currentFile = new File(_configPath, st.nextToken());
171			newLastModified = currentFile.lastModified();
172			if (newLastModified > lastModified) {
173			return true;
174			}
175			}
176			return false;
177			}
178	ajm	1.6
179	ajm	1.3	/**
180			* Overrides the {@link java.lang.Object#toString() Object.toString()}
181			* method to provide clean logging (every class should have this).
182			*
183	ajm	1.6	* This uses the uk.ac.ukc.iscream.util.FormatName class
184			* to format the toString()
185			*
186	ajm	1.3	* @return the name of this class and its CVS revision
187			*/
188			public String toString() {
189	ajm	1.6	return FormatName.getName(
190			_name,
191			getClass().getName(),
192			REVISION);
193	ajm	1.3	}
194
195			//---PRIVATE METHODS---
196
197			/**
198			* This is a recursive function private to this class.
199			* It constructs a hierarchy of files as a ";" serperated
200			* string which can be used to read in the configuration.
201			* This function calls itself.
202			*
203			* @param currentFile the current file to be processed
204	ajm	1.4	* @param readFiles used for recursion purposes only, these are the files it has read so far
205			*
206	ajm	1.3	* @return the current list that has been constructed
207			*
208			* @throws IOException if there is trouble reading the file
209			* @throws FileNotFoundException is there is trouble finding the file
210	ajm	1.4	* @throws CircularIncludeException this is if a circular include is detected
211	ajm	1.3	*/
212	ajm	1.4	private String getIncludedFiles(String currentFile, String readFiles) throws IOException, FileNotFoundException, Exception {
213
214			// check for circular include here
215			if (hasDuplicate(currentFile, readFiles) \|\| currentFile.equals(_systemConfigFile)) {
216			throw new CircularIncludeException(currentFile + " is included more than once");
217			}
218
219			// if there wasn't, we're gonna use this file, so make a note of it as read
220			// (note the use of the ";", this is for the hasDuplicate, function)
221			readFiles = readFiles + currentFile + ";";
222
223	ajm	1.3	Properties properties = new Properties();
224			properties.load(new FileInputStream(new File(_configPath, currentFile)));
225	ajm	1.4
226			// get the include property
227	ajm	1.3	String includes = properties.getProperty("include");
228	ajm	1.4
229			// if we're the last file with no includes, return our name
230	ajm	1.3	if (includes == null) {
231			return currentFile;
232	ajm	1.4
233			// otherwise, recurse over our includes
234	ajm	1.3	} else {
235			StringTokenizer st = new StringTokenizer(includes, ";");
236			String returnList= "";
237			while (st.hasMoreTokens()) {
238	ajm	1.4	returnList = getIncludedFiles(st.nextToken(), readFiles) + ";" + returnList;
239	ajm	1.3	}
240	ajm	1.4
241	ajm	1.3	return returnList + currentFile;
242			}
243			}
244
245			/**
246	ajm	1.4	* This simple method checks to see if a given
247			* file exists in the given list.
248			*
249			* @param file the file to check the list for
250			* @param fileList the list to check
251			*
252			* @return if the given file appeard in the list
253			*/
254			private boolean hasDuplicate(String file, String fileList) {
255			StringTokenizer st = new StringTokenizer(fileList, ";");
256			while (st.hasMoreTokens()) {
257			if (file.equals(st.nextToken())) {
258			return true;
259			}
260			}
261			return false;
262			}
263
264			/**
265	ajm	1.3	* Opens and loads the system configuration into the
266			* local reference _systemConfig
267			*/
268			private void loadSystemConfig() {
269	ajm	1.6	_logger.write(this.toString(), Logger.SYSMSG, "reloading " + _systemConfigFile);
270	ajm	1.3	// get a reference to the system config and store it
271			try {
272			// create the properties for the configuration
273			File systemConfigFile = new File(_configPath, _systemConfigFile);
274			Properties systemConfigHolder = new Properties();
275			systemConfigHolder.load(new FileInputStream(systemConfigFile));
276
277			// create the servant
278	ajm	1.6	ConfigurationServant ref = new ConfigurationServant(systemConfigHolder, _systemConfigFile, systemConfigFile.lastModified());
279			org.omg.CORBA.Object objRef = _refman.getRootPOA().servant_to_reference(ref);
280	ajm	1.3
281			// narrow it to a Configuration
282			_systemConfig = ConfigurationHelper.narrow(objRef);
283
284			} catch (Exception e) {
285	ajm	1.6	_logger.write(toString(), Logger.FATAL, "ERROR: " + e.getMessage());
286	ajm	1.3	}
287			}
288
289			//---ACCESSOR/MUTATOR METHODS---
290
291			//---ATTRIBUTES---
292
293			/**
294	ajm	1.6	* This is the friendly identifier of the
295			* component this class is running in.
296			* eg, a Filter may be called "filter1",
297			* If this class does not have an owning
298			* component, a name from the configuration
299			* can be placed here. This name could also
300			* be changed to null for utility classes.
301			*/
302			private String _name = Core.NAME;
303
304			/**
305			* This holds a reference to the
306			* system logger that is being used.
307	ajm	1.3	*/
308	ajm	1.6	private Logger _logger = ReferenceManager.getInstance().getLogger();
309	ajm	1.3
310			/**
311	ajm	1.6	* A reference to the reference manager in use
312	ajm	1.3	*/
313	ajm	1.6	private ReferenceManager _refman = ReferenceManager.getInstance();
314	ajm	1.3
315			/**
316			* The root path to all configurations
317			*/
318			private String _configPath;
319
320			/**
321			* The name of the file that contains the system configuration
322			*/
323			private String _systemConfigFile;
324
325			/**
326			* An instance of the system config
327			*/
328			private Configuration _systemConfig;
329
330			//---STATIC ATTRIBUTES---
331
332			}