server/core/ConfigurationManagerServant.java

//---PACKAGE DECLARATION---

//---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 1.3 2000/11/21 21:58:52 ajm4 Exp $
 */
class ConfigurationManagerServant extends ConfigurationManagerPOA {

//---FINAL ATTRIBUTES---

    /**
     * The current CVS revision of this class
     */
    public final String REVISION = "$Revision: 1.3 $";
    
//---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:	1.4
Committed:	Tue Nov 21 23:48:55 2000 UTC (23 years, 5 months ago) by ajm
Branch:	MAIN
Changes since 1.3:	+48 -11 lines
Log Message:	added support to detect circular includes also fixed problem of not passing the system.conf as a file to check for updates initial checkin of CircularIncludeException....oooo....
#	Content
1	//---PACKAGE DECLARATION---
2
3	//---IMPORTS---
4	import uk.ac.ukc.iscream.core.*;
5	import java.util.*;
6	import java.io.*;
7	import org.omg.CORBA.*;
8	import org.omg.PortableServer.*;
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	* @author $Author: ajm4 $
22	* @version $Id: ConfigurationManagerServant.java,v 1.3 2000/11/21 21:58:52 ajm4 Exp $
23	*/
24	class ConfigurationManagerServant extends ConfigurationManagerPOA {
25
26	//---FINAL ATTRIBUTES---
27
28	/**
29	* The current CVS revision of this class
30	*/
31	public final String REVISION = "$Revision: 1.3 $";
32
33	//---STATIC METHODS---
34
35	//---CONSTRUCTORS---
36
37	/**
38	* Creates a new ConfiguratorServant
39	* This class uses the System.properties to set internal values
40	*
41	* @param rootPOARef a reference to the RootPOA
42	* @param logRef a reference to the Logger
43	*/
44	ConfigurationManagerServant(POA rootPOARef, Logger logRef) {
45	// assign some local variables
46	_rootPOARef = rootPOARef;
47	_logRef = logRef;
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	_logRef.write(this.toString(), Logger.SYSINIT, "started");
56	_logRef.write(this.toString(), Logger.SYSMSG, "configuration location - " + _configPath);
57	_logRef.write(this.toString(), Logger.SYSMSG, "system configuration file - " + _systemConfigFile);
58	}
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	_logRef.write(this.toString(), Logger.SYSMSG, "got request for " + source);
83	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	_logRef.write(this.toString(), Logger.SYSMSG, "system config changed");
89	loadSystemConfig();
90	}
91
92	// we look for this entry in the systemConfig
93	String configFile = _systemConfig.getProperty("config." + source);
94	_logRef.write(this.toString(), Logger.DEBUG, "looking for config tree in - " + configFile);
95
96	// if there is an entry
97	if (configFile != null) {
98	try {
99	// get the file list of includes etc + the system config
100	String fileList = _systemConfigFile + ";" + getIncludedFiles(configFile, "");
101	_logRef.write(this.toString(), Logger.DEBUG, "config tree - " + fileList);
102
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	ConfigurationServant ref = new ConfigurationServant(properties, fileList, lastModified, _logRef);
134	org.omg.CORBA.Object objRef = _rootPOARef.servant_to_reference(ref);
135	config = ConfigurationHelper.narrow(objRef);
136
137	} catch (Exception e) {
138	// not sure what to do here
139	System.err.println("CONFIGURATION MANAGER ERROR: " + e);
140	e.printStackTrace(System.out);
141	}
142
143	// if there isn't an entry for the requested config
144	} else {
145	_logRef.write(this.toString(), Logger.DEBUG, "no configured config, returning " + _systemConfigFile);
146	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
179	/**
180	* Overrides the {@link java.lang.Object#toString() Object.toString()}
181	* method to provide clean logging (every class should have this).
182	*
183	* @return the name of this class and its CVS revision
184	*/
185	public String toString() {
186	return this.getClass().getName() + "(" + REVISION.substring(11, REVISION.length() - 2) + ")";
187	}
188
189	//---PRIVATE METHODS---
190
191	/**
192	* This is a recursive function private to this class.
193	* It constructs a hierarchy of files as a ";" serperated
194	* string which can be used to read in the configuration.
195	* This function calls itself.
196	*
197	* @param currentFile the current file to be processed
198	* @param readFiles used for recursion purposes only, these are the files it has read so far
199	*
200	* @return the current list that has been constructed
201	*
202	* @throws IOException if there is trouble reading the file
203	* @throws FileNotFoundException is there is trouble finding the file
204	* @throws CircularIncludeException this is if a circular include is detected
205	*/
206	private String getIncludedFiles(String currentFile, String readFiles) throws IOException, FileNotFoundException, Exception {
207
208	// check for circular include here
209	if (hasDuplicate(currentFile, readFiles) \|\| currentFile.equals(_systemConfigFile)) {
210	throw new CircularIncludeException(currentFile + " is included more than once");
211	}
212
213	// if there wasn't, we're gonna use this file, so make a note of it as read
214	// (note the use of the ";", this is for the hasDuplicate, function)
215	readFiles = readFiles + currentFile + ";";
216
217	Properties properties = new Properties();
218	properties.load(new FileInputStream(new File(_configPath, currentFile)));
219
220	// get the include property
221	String includes = properties.getProperty("include");
222
223	// if we're the last file with no includes, return our name
224	if (includes == null) {
225	return currentFile;
226
227	// otherwise, recurse over our includes
228	} else {
229	StringTokenizer st = new StringTokenizer(includes, ";");
230	String returnList= "";
231	while (st.hasMoreTokens()) {
232	returnList = getIncludedFiles(st.nextToken(), readFiles) + ";" + returnList;
233	}
234
235	return returnList + currentFile;
236	}
237	}
238
239	/**
240	* This simple method checks to see if a given
241	* file exists in the given list.
242	*
243	* @param file the file to check the list for
244	* @param fileList the list to check
245	*
246	* @return if the given file appeard in the list
247	*/
248	private boolean hasDuplicate(String file, String fileList) {
249	StringTokenizer st = new StringTokenizer(fileList, ";");
250	while (st.hasMoreTokens()) {
251	if (file.equals(st.nextToken())) {
252	return true;
253	}
254	}
255	return false;
256	}
257
258	/**
259	* Opens and loads the system configuration into the
260	* local reference _systemConfig
261	*/
262	private void loadSystemConfig() {
263	_logRef.write(this.toString(), Logger.SYSMSG, "reloading " + _systemConfigFile);
264	// get a reference to the system config and store it
265	try {
266	// create the properties for the configuration
267	File systemConfigFile = new File(_configPath, _systemConfigFile);
268	Properties systemConfigHolder = new Properties();
269	systemConfigHolder.load(new FileInputStream(systemConfigFile));
270
271	// create the servant
272	ConfigurationServant ref = new ConfigurationServant(systemConfigHolder, _systemConfigFile, systemConfigFile.lastModified(), _logRef);
273	org.omg.CORBA.Object objRef = _rootPOARef.servant_to_reference(ref);
274
275	// narrow it to a Configuration
276	_systemConfig = ConfigurationHelper.narrow(objRef);
277
278	} catch (Exception e) {
279	_logRef.write(this.toString(), Logger.FATAL, "ERROR: " + e.getMessage());
280	}
281	}
282
283	//---ACCESSOR/MUTATOR METHODS---
284
285	//---ATTRIBUTES---
286
287	/**
288	* Local storage of the RootPOA
289	*/
290	private POA _rootPOARef;
291
292	/**
293	* Local storage of the Logger
294	*/
295	private Logger _logRef;
296
297	/**
298	* The root path to all configurations
299	*/
300	private String _configPath;
301
302	/**
303	* The name of the file that contains the system configuration
304	*/
305	private String _systemConfigFile;
306
307	/**
308	* An instance of the system config
309	*/
310	private Configuration _systemConfig;
311
312	//---STATIC ATTRIBUTES---
313
314	}