server/core/ConfigurationManagerServant.java

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

//---IMPORTS---
import uk.ac.ukc.iscream.util.*;
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 1.5 2000/11/29 21:27:08 ajm4 Exp $
 */
class ConfigurationManagerServant extends ConfigurationManagerPOA {

//---FINAL ATTRIBUTES---

    /**
     * The current CVS revision of this class
     */
    public final String REVISION = "$Revision: 1.5 $";
    
//---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:	1.6
Committed:	Tue Dec 12 18:26:52 2000 UTC (23 years, 5 months ago) by ajm
Branch:	MAIN
Changes since 1.5:	+49 -33 lines
Log Message:	tidied up the code
#	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	ajm	1.3	import java.util.*;
7			import java.io.*;
8
9			/**
10			* This class is essentially a Configuration factory.
11			* This class implements the Configurator IDL and allows
12			* other classes in the system ot obtain their Configuration
13			*
14			* On construction it requires a reference to the RootPOA
15			* to allow it to create Configuration objects to be
16			* returned.
17			*
18			* It also relies on the System.properties to set internal values.
19			*
20	ajm	1.6	* ###
21			* A point to note is that this class does NOT yet manage
22			* created configurations which may cause memory problems!
23			* ###
24			*
25	ajm	1.4	* @author $Author: ajm4 $
26	ajm	1.6	* @version $Id: ConfigurationManagerServant.java,v 1.5 2000/11/29 21:27:08 ajm4 Exp $
27	ajm	1.3	*/
28			class ConfigurationManagerServant extends ConfigurationManagerPOA {
29
30			//---FINAL ATTRIBUTES---
31
32			/**
33			* The current CVS revision of this class
34			*/
35	ajm	1.6	public final String REVISION = "$Revision: 1.5 $";
36	ajm	1.3
37			//---STATIC METHODS---
38
39			//---CONSTRUCTORS---
40
41			/**
42			* Creates a new ConfiguratorServant
43			* This class uses the System.properties to set internal values
44			*/
45	ajm	1.6	ConfigurationManagerServant() {
46	ajm	1.3	// assign some local variables
47			_configPath = System.getProperty("uk.ac.ukc.iscream.ConfigurationLocation");
48			_systemConfigFile = System.getProperty("uk.ac.ukc.iscream.SystemConfigurationFile");
49
50			// load the system config
51			loadSystemConfig();
52
53			// log our status
54	ajm	1.6	_logger.write(toString(), Logger.SYSINIT, "started");
55			_logger.write(toString(), Logger.SYSMSG, "configuration location - " + _configPath);
56			_logger.write(toString(), Logger.SYSMSG, "system configuration file - " + _systemConfigFile);
57	ajm	1.3	}
58
59			//---PUBLIC METHODS---
60
61			/**
62			* Returns a Configuration object which contains
63			* the configuration data requested by the calling
64			* object.
65			*
66			* This method will look in the systemConfig file
67			* for an entry for this "source", if there is no
68			* entry it returns a refernce to the system
69			* config. If there are any errors in reading the
70			* configuration, it returns null, the caller is
71			* expected to be able to handle this.
72			*
73			* This method also checks to see if the system.conf
74			* file has been updated and reloads its reference if
75			* needed.
76			*
77			* @param source the configuration required
78			* @return the Configuration
79			*/
80			public Configuration getConfiguration(String source) {
81	ajm	1.6	_logger.write(toString(), Logger.SYSMSG, "got request for " + source);
82	ajm	1.3	Configuration config = null;
83
84			// check to see if we need to reload the system config
85			// because it has changed
86			if (isModified(_systemConfig.getFileList(), _systemConfig.getLastModified())) {
87	ajm	1.6	_logger.write(toString(), Logger.SYSMSG, "system config changed");
88	ajm	1.3	loadSystemConfig();
89			}
90
91			// we look for this entry in the systemConfig
92			String configFile = _systemConfig.getProperty("config." + source);
93	ajm	1.6	_logger.write(toString(), Logger.DEBUG, "looking for config tree in - " + configFile);
94	ajm	1.3
95			// if there is an entry
96			if (configFile != null) {
97			try {
98	ajm	1.4	// get the file list of includes etc + the system config
99			String fileList = _systemConfigFile + ";" + getIncludedFiles(configFile, "");
100	ajm	1.6	_logger.write(toString(), Logger.DEBUG, "config tree - " + fileList);
101	ajm	1.3
102			// build the properites here from the filelist....
103			StringTokenizer st = new StringTokenizer(fileList, ";");
104
105			// some holders for variables
106			File currentFile;
107			long lastModified, newLastModified;
108			Properties properties, prevProperties;
109
110			// the root of all configurations will be the system config
111			// so we need to open the properties of that
112			Properties defaultProperties = new Properties();
113			currentFile = new File(_configPath, _systemConfigFile);
114			lastModified = currentFile.lastModified();
115			defaultProperties.load(new FileInputStream(currentFile));
116
117			// This loop then iterates over the file list
118			// creates the properties to be passed to the
119			// Configuration constructor
120			do {
121			properties = new Properties(defaultProperties);
122			currentFile = new File(_configPath, st.nextToken());
123			newLastModified = currentFile.lastModified();
124			if (newLastModified > lastModified) {
125			lastModified = newLastModified;
126			}
127			properties.load(new FileInputStream(currentFile));
128			defaultProperties = properties;
129			} while (st.hasMoreTokens());
130
131			// this creates the configuration, all nice, ready to be returned
132	ajm	1.6	ConfigurationServant ref = new ConfigurationServant(properties, fileList, lastModified);
133			org.omg.CORBA.Object objRef = _refman.getRootPOA().servant_to_reference(ref);
134	ajm	1.3	config = ConfigurationHelper.narrow(objRef);
135
136			} catch (Exception e) {
137			// not sure what to do here
138	ajm	1.6	// so we just log the error
139			_logger.write(toString(), Logger.ERROR, "ERROR - " + e.getMessage());
140	ajm	1.3	}
141
142	ajm	1.4	// if there isn't an entry for the requested config
143	ajm	1.3	} else {
144	ajm	1.6	_logger.write(toString(), Logger.DEBUG, "no configured config, returning " + _systemConfigFile);
145	ajm	1.3	config = _systemConfig;
146			}
147
148			// if this is null at this point, then there will have been an error
149			return config;
150			}
151
152
153			/**
154			* When passed a file list and a current value for the lastModified
155			* of the current configuration, this method compares the value
156			* to the actual value of the configuration files to determine
157			* whether or not the configuration has been modified.
158			*
159			* @param fileList a list of files that the caller uses for configuration
160			* @param lastModified the last modified date of the callers configuration
161			*
162			* @return whether or not the configuration has been modified
163			*/
164			public boolean isModified(String fileList, long lastModified) {
165			StringTokenizer st = new StringTokenizer(fileList, ";");
166			long newLastModified;
167			File currentFile;
168			while (st.hasMoreTokens()) {
169			currentFile = new File(_configPath, st.nextToken());
170			newLastModified = currentFile.lastModified();
171			if (newLastModified > lastModified) {
172			return true;
173			}
174			}
175			return false;
176			}
177	ajm	1.6
178	ajm	1.3	/**
179			* Overrides the {@link java.lang.Object#toString() Object.toString()}
180			* method to provide clean logging (every class should have this).
181			*
182	ajm	1.6	* This uses the uk.ac.ukc.iscream.util.FormatName class
183			* to format the toString()
184			*
185	ajm	1.3	* @return the name of this class and its CVS revision
186			*/
187			public String toString() {
188	ajm	1.6	return FormatName.getName(
189			_name,
190			getClass().getName(),
191			REVISION);
192	ajm	1.3	}
193
194			//---PRIVATE METHODS---
195
196			/**
197			* This is a recursive function private to this class.
198			* It constructs a hierarchy of files as a ";" serperated
199			* string which can be used to read in the configuration.
200			* This function calls itself.
201			*
202			* @param currentFile the current file to be processed
203	ajm	1.4	* @param readFiles used for recursion purposes only, these are the files it has read so far
204			*
205	ajm	1.3	* @return the current list that has been constructed
206			*
207			* @throws IOException if there is trouble reading the file
208			* @throws FileNotFoundException is there is trouble finding the file
209	ajm	1.4	* @throws CircularIncludeException this is if a circular include is detected
210	ajm	1.3	*/
211	ajm	1.4	private String getIncludedFiles(String currentFile, String readFiles) throws IOException, FileNotFoundException, Exception {
212
213			// check for circular include here
214			if (hasDuplicate(currentFile, readFiles) \|\| currentFile.equals(_systemConfigFile)) {
215			throw new CircularIncludeException(currentFile + " is included more than once");
216			}
217
218			// if there wasn't, we're gonna use this file, so make a note of it as read
219			// (note the use of the ";", this is for the hasDuplicate, function)
220			readFiles = readFiles + currentFile + ";";
221
222	ajm	1.3	Properties properties = new Properties();
223			properties.load(new FileInputStream(new File(_configPath, currentFile)));
224	ajm	1.4
225			// get the include property
226	ajm	1.3	String includes = properties.getProperty("include");
227	ajm	1.4
228			// if we're the last file with no includes, return our name
229	ajm	1.3	if (includes == null) {
230			return currentFile;
231	ajm	1.4
232			// otherwise, recurse over our includes
233	ajm	1.3	} else {
234			StringTokenizer st = new StringTokenizer(includes, ";");
235			String returnList= "";
236			while (st.hasMoreTokens()) {
237	ajm	1.4	returnList = getIncludedFiles(st.nextToken(), readFiles) + ";" + returnList;
238	ajm	1.3	}
239	ajm	1.4
240	ajm	1.3	return returnList + currentFile;
241			}
242			}
243
244			/**
245	ajm	1.4	* This simple method checks to see if a given
246			* file exists in the given list.
247			*
248			* @param file the file to check the list for
249			* @param fileList the list to check
250			*
251			* @return if the given file appeard in the list
252			*/
253			private boolean hasDuplicate(String file, String fileList) {
254			StringTokenizer st = new StringTokenizer(fileList, ";");
255			while (st.hasMoreTokens()) {
256			if (file.equals(st.nextToken())) {
257			return true;
258			}
259			}
260			return false;
261			}
262
263			/**
264	ajm	1.3	* Opens and loads the system configuration into the
265			* local reference _systemConfig
266			*/
267			private void loadSystemConfig() {
268	ajm	1.6	_logger.write(this.toString(), Logger.SYSMSG, "reloading " + _systemConfigFile);
269	ajm	1.3	// get a reference to the system config and store it
270			try {
271			// create the properties for the configuration
272			File systemConfigFile = new File(_configPath, _systemConfigFile);
273			Properties systemConfigHolder = new Properties();
274			systemConfigHolder.load(new FileInputStream(systemConfigFile));
275
276			// create the servant
277	ajm	1.6	ConfigurationServant ref = new ConfigurationServant(systemConfigHolder, _systemConfigFile, systemConfigFile.lastModified());
278			org.omg.CORBA.Object objRef = _refman.getRootPOA().servant_to_reference(ref);
279	ajm	1.3
280			// narrow it to a Configuration
281			_systemConfig = ConfigurationHelper.narrow(objRef);
282
283			} catch (Exception e) {
284	ajm	1.6	_logger.write(toString(), Logger.FATAL, "ERROR: " + e.getMessage());
285	ajm	1.3	}
286			}
287
288			//---ACCESSOR/MUTATOR METHODS---
289
290			//---ATTRIBUTES---
291
292			/**
293	ajm	1.6	* This is the friendly identifier of the
294			* component this class is running in.
295			* eg, a Filter may be called "filter1",
296			* If this class does not have an owning
297			* component, a name from the configuration
298			* can be placed here. This name could also
299			* be changed to null for utility classes.
300			*/
301			private String _name = Core.NAME;
302
303			/**
304			* This holds a reference to the
305			* system logger that is being used.
306	ajm	1.3	*/
307	ajm	1.6	private Logger _logger = ReferenceManager.getInstance().getLogger();
308	ajm	1.3
309			/**
310	ajm	1.6	* A reference to the reference manager in use
311	ajm	1.3	*/
312	ajm	1.6	private ReferenceManager _refman = ReferenceManager.getInstance();
313	ajm	1.3
314			/**
315			* The root path to all configurations
316			*/
317			private String _configPath;
318
319			/**
320			* The name of the file that contains the system configuration
321			*/
322			private String _systemConfigFile;
323
324			/**
325			* An instance of the system config
326			*/
327			private Configuration _systemConfig;
328
329			//---STATIC ATTRIBUTES---
330
331			}