server/core/ConfigurationManagerServant.java

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

//---IMPORTS---
import uk.ac.ukc.iscream.core.*;
import java.util.*;
import java.io.*;
import org.omg.CORBA.*;
import org.omg.PortableServer.*;

/**
 * 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.
 *
 * @author  $Author: ajm4 $
 * @version $Id: ConfigurationManagerServant.java,v 1.4 2000/11/21 23:48:55 ajm4 Exp $
 */
class ConfigurationManagerServant extends ConfigurationManagerPOA {

//---FINAL ATTRIBUTES---

    /**
     * The current CVS revision of this class
     */
    public final String REVISION = "$Revision: 1.4 $";
    
//---STATIC METHODS---

//---CONSTRUCTORS---

    /**
     * Creates a new ConfiguratorServant
     * This class uses the System.properties to set internal values
     *
     * @param rootPOARef a reference to the RootPOA
     * @param logRef a reference to the Logger
     */
    ConfigurationManagerServant(POA rootPOARef, Logger logRef) {
        // assign some local variables
        _rootPOARef = rootPOARef;
        _logRef = logRef;
        _configPath = System.getProperty("uk.ac.ukc.iscream.ConfigurationLocation");
        _systemConfigFile = System.getProperty("uk.ac.ukc.iscream.SystemConfigurationFile");

        // load the system config
        loadSystemConfig();

        // log our status
        _logRef.write(this.toString(), Logger.SYSINIT, "started");
        _logRef.write(this.toString(), Logger.SYSMSG, "configuration location - " + _configPath);
        _logRef.write(this.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) {
        _logRef.write(this.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())) {
            _logRef.write(this.toString(), Logger.SYSMSG, "system config changed");
            loadSystemConfig();
        }

        // we look for this entry in the systemConfig
        String configFile = _systemConfig.getProperty("config." + source);
        _logRef.write(this.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, "");            
                _logRef.write(this.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, _logRef);
                org.omg.CORBA.Object objRef = _rootPOARef.servant_to_reference(ref);
                config = ConfigurationHelper.narrow(objRef);

            } catch (Exception e) {
                // not sure what to do here
                System.err.println("CONFIGURATION MANAGER ERROR: " + e);
                e.printStackTrace(System.out);
            }
            
        // if there isn't an entry for the requested config
        } else {
            _logRef.write(this.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).
     *
     * @return the name of this class and its CVS revision
     */
    public String toString() {
        return this.getClass().getName() + "(" + REVISION.substring(11, REVISION.length() - 2) + ")";
    }

//---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() {
        _logRef.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(), _logRef);
            org.omg.CORBA.Object objRef = _rootPOARef.servant_to_reference(ref);
            
            // narrow it to a Configuration
            _systemConfig = ConfigurationHelper.narrow(objRef);
            
        } catch (Exception e) {
            _logRef.write(this.toString(), Logger.FATAL, "ERROR: " + e.getMessage());
        }
    }

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

//---ATTRIBUTES---

    /**
     * Local storage of the RootPOA
     */
    private POA _rootPOARef;
    
    /**
     * Local storage of the Logger
     */
    private Logger _logRef;
    
    /**
     * 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:	1.5
Committed:	Wed Nov 29 21:27:08 2000 UTC (23 years, 6 months ago) by ajm
Branch:	MAIN
Branch point for:	SERVER_PACKAGEBUILD
Changes since 1.4:	+3 -2 lines
Log Message:	Update for package move.
#	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			import uk.ac.ukc.iscream.core.*;
6			import java.util.*;
7			import java.io.*;
8			import org.omg.CORBA.*;
9			import org.omg.PortableServer.*;
10
11			/**
12			* This class is essentially a Configuration factory.
13			* This class implements the Configurator IDL and allows
14			* other classes in the system ot obtain their Configuration
15			*
16			* On construction it requires a reference to the RootPOA
17			* to allow it to create Configuration objects to be
18			* returned.
19			*
20			* It also relies on the System.properties to set internal values.
21			*
22	ajm	1.4	* @author $Author: ajm4 $
23	ajm	1.5	* @version $Id: ConfigurationManagerServant.java,v 1.4 2000/11/21 23:48:55 ajm4 Exp $
24	ajm	1.3	*/
25			class ConfigurationManagerServant extends ConfigurationManagerPOA {
26
27			//---FINAL ATTRIBUTES---
28
29			/**
30			* The current CVS revision of this class
31			*/
32	ajm	1.5	public final String REVISION = "$Revision: 1.4 $";
33	ajm	1.3
34			//---STATIC METHODS---
35
36			//---CONSTRUCTORS---
37
38			/**
39			* Creates a new ConfiguratorServant
40			* This class uses the System.properties to set internal values
41			*
42			* @param rootPOARef a reference to the RootPOA
43			* @param logRef a reference to the Logger
44			*/
45			ConfigurationManagerServant(POA rootPOARef, Logger logRef) {
46			// assign some local variables
47			_rootPOARef = rootPOARef;
48			_logRef = logRef;
49			_configPath = System.getProperty("uk.ac.ukc.iscream.ConfigurationLocation");
50			_systemConfigFile = System.getProperty("uk.ac.ukc.iscream.SystemConfigurationFile");
51
52			// load the system config
53			loadSystemConfig();
54
55			// log our status
56			_logRef.write(this.toString(), Logger.SYSINIT, "started");
57			_logRef.write(this.toString(), Logger.SYSMSG, "configuration location - " + _configPath);
58			_logRef.write(this.toString(), Logger.SYSMSG, "system configuration file - " + _systemConfigFile);
59			}
60
61			//---PUBLIC METHODS---
62
63			/**
64			* Returns a Configuration object which contains
65			* the configuration data requested by the calling
66			* object.
67			*
68			* This method will look in the systemConfig file
69			* for an entry for this "source", if there is no
70			* entry it returns a refernce to the system
71			* config. If there are any errors in reading the
72			* configuration, it returns null, the caller is
73			* expected to be able to handle this.
74			*
75			* This method also checks to see if the system.conf
76			* file has been updated and reloads its reference if
77			* needed.
78			*
79			* @param source the configuration required
80			* @return the Configuration
81			*/
82			public Configuration getConfiguration(String source) {
83			_logRef.write(this.toString(), Logger.SYSMSG, "got request for " + source);
84			Configuration config = null;
85
86			// check to see if we need to reload the system config
87			// because it has changed
88			if (isModified(_systemConfig.getFileList(), _systemConfig.getLastModified())) {
89			_logRef.write(this.toString(), Logger.SYSMSG, "system config changed");
90			loadSystemConfig();
91			}
92
93			// we look for this entry in the systemConfig
94			String configFile = _systemConfig.getProperty("config." + source);
95			_logRef.write(this.toString(), Logger.DEBUG, "looking for config tree in - " + configFile);
96
97			// if there is an entry
98			if (configFile != null) {
99			try {
100	ajm	1.4	// get the file list of includes etc + the system config
101			String fileList = _systemConfigFile + ";" + getIncludedFiles(configFile, "");
102	ajm	1.3	_logRef.write(this.toString(), Logger.DEBUG, "config tree - " + fileList);
103
104			// build the properites here from the filelist....
105			StringTokenizer st = new StringTokenizer(fileList, ";");
106
107			// some holders for variables
108			File currentFile;
109			long lastModified, newLastModified;
110			Properties properties, prevProperties;
111
112			// the root of all configurations will be the system config
113			// so we need to open the properties of that
114			Properties defaultProperties = new Properties();
115			currentFile = new File(_configPath, _systemConfigFile);
116			lastModified = currentFile.lastModified();
117			defaultProperties.load(new FileInputStream(currentFile));
118
119			// This loop then iterates over the file list
120			// creates the properties to be passed to the
121			// Configuration constructor
122			do {
123			properties = new Properties(defaultProperties);
124			currentFile = new File(_configPath, st.nextToken());
125			newLastModified = currentFile.lastModified();
126			if (newLastModified > lastModified) {
127			lastModified = newLastModified;
128			}
129			properties.load(new FileInputStream(currentFile));
130			defaultProperties = properties;
131			} while (st.hasMoreTokens());
132
133			// this creates the configuration, all nice, ready to be returned
134			ConfigurationServant ref = new ConfigurationServant(properties, fileList, lastModified, _logRef);
135			org.omg.CORBA.Object objRef = _rootPOARef.servant_to_reference(ref);
136			config = ConfigurationHelper.narrow(objRef);
137
138			} catch (Exception e) {
139			// not sure what to do here
140			System.err.println("CONFIGURATION MANAGER ERROR: " + e);
141			e.printStackTrace(System.out);
142			}
143
144	ajm	1.4	// if there isn't an entry for the requested config
145	ajm	1.3	} else {
146			_logRef.write(this.toString(), Logger.DEBUG, "no configured config, returning " + _systemConfigFile);
147			config = _systemConfig;
148			}
149
150			// if this is null at this point, then there will have been an error
151			return config;
152			}
153
154
155			/**
156			* When passed a file list and a current value for the lastModified
157			* of the current configuration, this method compares the value
158			* to the actual value of the configuration files to determine
159			* whether or not the configuration has been modified.
160			*
161			* @param fileList a list of files that the caller uses for configuration
162			* @param lastModified the last modified date of the callers configuration
163			*
164			* @return whether or not the configuration has been modified
165			*/
166			public boolean isModified(String fileList, long lastModified) {
167			StringTokenizer st = new StringTokenizer(fileList, ";");
168			long newLastModified;
169			File currentFile;
170			while (st.hasMoreTokens()) {
171			currentFile = new File(_configPath, st.nextToken());
172			newLastModified = currentFile.lastModified();
173			if (newLastModified > lastModified) {
174			return true;
175			}
176			}
177			return false;
178			}
179
180			/**
181			* Overrides the {@link java.lang.Object#toString() Object.toString()}
182			* method to provide clean logging (every class should have this).
183			*
184			* @return the name of this class and its CVS revision
185			*/
186			public String toString() {
187			return this.getClass().getName() + "(" + REVISION.substring(11, REVISION.length() - 2) + ")";
188			}
189
190			//---PRIVATE METHODS---
191
192			/**
193			* This is a recursive function private to this class.
194			* It constructs a hierarchy of files as a ";" serperated
195			* string which can be used to read in the configuration.
196			* This function calls itself.
197			*
198			* @param currentFile the current file to be processed
199	ajm	1.4	* @param readFiles used for recursion purposes only, these are the files it has read so far
200			*
201	ajm	1.3	* @return the current list that has been constructed
202			*
203			* @throws IOException if there is trouble reading the file
204			* @throws FileNotFoundException is there is trouble finding the file
205	ajm	1.4	* @throws CircularIncludeException this is if a circular include is detected
206	ajm	1.3	*/
207	ajm	1.4	private String getIncludedFiles(String currentFile, String readFiles) throws IOException, FileNotFoundException, Exception {
208
209			// check for circular include here
210			if (hasDuplicate(currentFile, readFiles) \|\| currentFile.equals(_systemConfigFile)) {
211			throw new CircularIncludeException(currentFile + " is included more than once");
212			}
213
214			// if there wasn't, we're gonna use this file, so make a note of it as read
215			// (note the use of the ";", this is for the hasDuplicate, function)
216			readFiles = readFiles + currentFile + ";";
217
218	ajm	1.3	Properties properties = new Properties();
219			properties.load(new FileInputStream(new File(_configPath, currentFile)));
220	ajm	1.4
221			// get the include property
222	ajm	1.3	String includes = properties.getProperty("include");
223	ajm	1.4
224			// if we're the last file with no includes, return our name
225	ajm	1.3	if (includes == null) {
226			return currentFile;
227	ajm	1.4
228			// otherwise, recurse over our includes
229	ajm	1.3	} else {
230			StringTokenizer st = new StringTokenizer(includes, ";");
231			String returnList= "";
232			while (st.hasMoreTokens()) {
233	ajm	1.4	returnList = getIncludedFiles(st.nextToken(), readFiles) + ";" + returnList;
234	ajm	1.3	}
235	ajm	1.4
236	ajm	1.3	return returnList + currentFile;
237			}
238			}
239
240			/**
241	ajm	1.4	* This simple method checks to see if a given
242			* file exists in the given list.
243			*
244			* @param file the file to check the list for
245			* @param fileList the list to check
246			*
247			* @return if the given file appeard in the list
248			*/
249			private boolean hasDuplicate(String file, String fileList) {
250			StringTokenizer st = new StringTokenizer(fileList, ";");
251			while (st.hasMoreTokens()) {
252			if (file.equals(st.nextToken())) {
253			return true;
254			}
255			}
256			return false;
257			}
258
259			/**
260	ajm	1.3	* Opens and loads the system configuration into the
261			* local reference _systemConfig
262			*/
263			private void loadSystemConfig() {
264	ajm	1.4	_logRef.write(this.toString(), Logger.SYSMSG, "reloading " + _systemConfigFile);
265	ajm	1.3	// get a reference to the system config and store it
266			try {
267			// create the properties for the configuration
268			File systemConfigFile = new File(_configPath, _systemConfigFile);
269			Properties systemConfigHolder = new Properties();
270			systemConfigHolder.load(new FileInputStream(systemConfigFile));
271
272			// create the servant
273			ConfigurationServant ref = new ConfigurationServant(systemConfigHolder, _systemConfigFile, systemConfigFile.lastModified(), _logRef);
274			org.omg.CORBA.Object objRef = _rootPOARef.servant_to_reference(ref);
275
276			// narrow it to a Configuration
277			_systemConfig = ConfigurationHelper.narrow(objRef);
278
279			} catch (Exception e) {
280			_logRef.write(this.toString(), Logger.FATAL, "ERROR: " + e.getMessage());
281			}
282			}
283
284			//---ACCESSOR/MUTATOR METHODS---
285
286			//---ATTRIBUTES---
287
288			/**
289			* Local storage of the RootPOA
290			*/
291			private POA _rootPOARef;
292
293			/**
294			* Local storage of the Logger
295			*/
296			private Logger _logRef;
297
298			/**
299			* The root path to all configurations
300			*/
301			private String _configPath;
302
303			/**
304			* The name of the file that contains the system configuration
305			*/
306			private String _systemConfigFile;
307
308			/**
309			* An instance of the system config
310			*/
311			private Configuration _systemConfig;
312
313			//---STATIC ATTRIBUTES---
314
315			}