server/componentmanager/ReferenceManager.java

//---PACKAGE DECLARATION---
package uk.org.iscream.componentmanager;

//---IMPORTS---
import org.omg.CORBA.ORB;
import org.omg.CosNaming.*;
import org.omg.PortableServer.*;
import uk.org.iscream.core.*;
import uk.org.iscream.util.*;

/**
 * This class returns references for global system objects.
 * This class is used to create and return references to objects
 * that are required throughout the system.  Most of which
 * are CORBA based.  It also manages the ORB for the component.
 *
 * It is a singleton object with a static method to obtain a
 * reference to it.  This removes the need for passing
 * references to all the objects it contains throughout 
 * a component.
 *
 * @author  $Author: ajm4 $
 * @version $Id: ReferenceManager.java,v 1.12 2001/02/23 16:55:12 ajm4 Exp $
 */
public class ReferenceManager {

//---FINAL ATTRIBUTES---
   
    /**
     * The current CVS revision of this class
     */
    public final String REVISION = "$Revision: 1.12 $";
    
//---STATIC METHODS---

    /**
     * This returns a reference to the single instance of the
     * ReferenceManager.
     *
     * This creates the single instance of the ReferenceManager
     * if it does not exist by calling the private constructor.
     *
     * @return a reference to the ReferenceManager
     */
    public static ReferenceManager getInstance() {
        if (_instance == null) {
            _instance = new ReferenceManager();
        }
        return _instance;
    }

//---CONSTRUCTORS---

    /**
     * This is a private constructor
     * This ensures that the system performs according to a Singleton design pattern
     */
    private ReferenceManager() {
        _orb = ORB.init(new String[] {}, null);
    }

//---PUBLIC METHODS---

    /**
     * Obtains a CORBA reference through the naming service
     * for the named object.
     * Calls the dieWithError() if any exceptions happen!
     *
     * @param name the name of the CORBA object to resolve
     *
     * @return a reference to the object
     */
    public org.omg.CORBA.Object getCORBARef(String name) {
        org.omg.CORBA.Object objRef = null;
        try {
            objRef = getNS().resolve(getNS().to_name(name));
        } catch (org.omg.CosNaming.NamingContextPackage.CannotProceed e) {
            dieWithError("\nCRITICAL:Naming Service Cannot Proceed - when resolving reference to " + name + "!\n" + 
                              "         Please check with your CORBA naming service provider.");
        } catch (org.omg.CosNaming.NamingContextPackage.InvalidName e) {
            dieWithError("\nCRITICAL:Invalid Name - when resolving reference to " + name + "!\n" + 
                              "         Please check with your CORBA naming service provider.");
        } catch (org.omg.CosNaming.NamingContextPackage.NotFound e) {
            recoverWithError("\nCRITICAL:Not Found - when resolving reference to " + name + "!\n" + 
                              "         Please check that this component is running.");
        }
        return objRef;
    }

    /** 
     * Binds a given servant with the given name
     * to the naming service.
     * Calls the dieWithError() if any exceptions happen!
     *
     * @param objRef a reverence to the servant object
     * @param name the name to bind to the naming service with
     */
    public void bindToOrb(org.omg.PortableServer.Servant objRef, String name) {
        try {
            getNS().bind(getNS().to_name(name), getRootPOA().servant_to_reference(objRef));
        } catch (org.omg.PortableServer.POAPackage.WrongPolicy e) {
            dieWithError("\nCRITICAL:Wrong POA Policy - when binding " + name + "!\n" + 
                              "         This indicates an error with your ORB.");
        } catch (org.omg.PortableServer.POAPackage.ServantNotActive e) {
            dieWithError("\nCRITICAL:ServantNotActive - when binding " + name + "!\n" + 
                              "         This indicates an error with your ORB.");
        } catch (org.omg.CosNaming.NamingContextPackage.InvalidName e) {
            dieWithError("\nCRITICAL:Invalid Name - when binding " + name + "!\n" + 
                              "         Please check with your CORBA naming service provider.");
        } catch (org.omg.CosNaming.NamingContextPackage.CannotProceed e) {
            dieWithError("\nCRITICAL:Naming Service Cannot Proceed - when binding " + name + "!\n" + 
                              "         Please check with your CORBA naming service provider.");
        } catch (org.omg.CosNaming.NamingContextPackage.NotFound e) {
            recoverWithError("\nCRITICAL:Naming Service Not Found - when binding " + name + "!\n" + 
                              "         Please check with your CORBA naming service provider.");
        } catch (org.omg.CosNaming.NamingContextPackage.AlreadyBound e) {
            dieWithError("\nCRITICAL:Already Bound - when binding " + name + "!\n" + 
                              "         Another component with this name is already running.");
        }
    }
    
    /**
     * Activates the POA
     * Calls the dieWithError() if any exceptions happen!
     */
    public void activatePOA() {
        try {
            getRootPOA().the_POAManager().activate();
        } catch (org.omg.PortableServer.POAManagerPackage.AdapterInactive e) {
            dieWithError("\nCRITICAL:POA Set Inactive - when trying to activate POA!\n" + 
                              "         This indicates an error with your ORB.");
        }
    }
    
    /**
     * Overrides the {@link java.lang.Object#toString() Object.toString()}
     * method to provide clean logging (every class should have this).
     *
     * This uses the uk.org.iscream.util.NameFormat class
     * to format the toString()
     *
     * @return the name of this class and its CVS revision
     */
    public String toString() {
        return FormatName.getName(
            _name,
            getClass().getName(),
            REVISION);
    }

//---PRIVATE METHODS---

    /**
     * If there are any CORBA errors this method is called with the 
     * error message.
     *
     * The exception this throws is generic to CORBA communication
     * problems, this is a Runtime exception and is typically only
     * explicitly caught in the ComponentManager for the current VM
     * The ComponentManager can then decide what course of action to 
     * take.
     *
     * Also, if it can, it will log the message with the logger.
     *
     * @param message the error message to die with
     */
    private void recoverWithError(String message) throws ComponentCORBAException {
        if (_logger != null) {
            _logger.write(toString(), Logger.WARNING, "component CORBA error - " + message);
        }
        throw new ComponentCORBAException(message);
    }


    /**
     * If there are any CORBA errors this method is called with the 
     * error message.
     *
     * Currently this prints the error, on the local err stream.  Will
     * print to the logger if one is available.
     *
     * ANY CALLS TO THIS METHOD CAUSE
     * THE SYSTEM TO EXIT WITH A NON
     * ZERO CODE!
     *
     * @param message the error message to die with
     */
    private void dieWithError(String message) {
        System.err.println(message);
        if (_logger != null) {
            _logger.write(toString(), Logger.FATAL, message);
        }
        System.exit(1);
    }


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

    /**
     * Returns a reference to the ORB
     *
     * @return the reference this class holds
     */
    public ORB getORB() {
        return _orb;
    }

    /**
     * Returns a reference to the Root POA
     * Calls the dieWithError() if any exceptions happen!
     *
     * @return the reference this class holds
     */
    public POA getRootPOA() {
        if (_rootPOA == null) {
            org.omg.CORBA.Object objRef = null;
            try {
                objRef = getORB().resolve_initial_references("RootPOA");
            } catch (org.omg.CORBA.ORBPackage.InvalidName e) {
                dieWithError("\nCRITICAL:Unable to resolve reference to the RootPOA!\n" + 
                                  "         This indicates an error with your ORB.");
            }
            _rootPOA = POAHelper.narrow(objRef);
        }
        return _rootPOA;
    }
    
    /**
     * Returns a reference to the Naming Service
     * Calls the dieWithError() if any exceptions happen!
     *
     * @return the reference this class holds
     */
    public NamingContextExt getNS() {
        if (_ns == null) {
            org.omg.CORBA.Object objRef = null;
            try {
                objRef = getORB().resolve_initial_references("NameService");
            } catch (org.omg.CORBA.ORBPackage.InvalidName e) {
                dieWithError("\nCRITICAL:Unable to resolve reference to the Naming Service!\n" +
                                  "         Please check with your CORBA naming service provider.");
            }
            _ns = NamingContextExtHelper.narrow(objRef);
        }
        // check we managed to talk to the naming service
        if (_ns == null) {
            dieWithError("\nCRITICAL:Unable to resolve reference to the Naming Service!\n" +
                              "         Please check with your CORBA naming service provider.");
        }
        return _ns;
    }
    
    /**
     * Returns a reference to the configuration manager
     * Calls the dieWithError() if any exceptions happen!
     *
     * @return the reference this class holds
     */
    public ConfigurationManager getCM() {
        if (_cm == null) {
            _cm = ConfigurationManagerHelper.narrow(getCORBARef("iscream.ConfigurationManager"));
        }
        // check we managed to talk to the configuration manager
        if (_cm == null) {
            dieWithError("\nCRITICAL:Unable to resolve reference to the Configuration Manager!\n" +
                              "         Please check with your CORBA naming service provider.");
        }
        return _cm;
    }

    /**
     * Returns a reference to the logger
     * This will throw a Error if there is an error
     *
     * @return the reference this class holds
     */
    public Logger getLogger() {
        if (_logger == null) {
            _logger = LoggerHelper.narrow(getCORBARef("iscream.Logger"));
        }
        return _logger;
    }
    
//---ATTRIBUTES---
    
    /**
     * The ORB
     */
    private ORB _orb;
    
    /**
     * The Naming Service
     */
    private NamingContextExt _ns;
    
    /**
     * The Root POA
     */
    private POA _rootPOA;

    /**
     * The configuration manager
     */
    private ConfigurationManager _cm;

    /**
     * The logger
     */
    private Logger _logger;
    
    /**
     * 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 = null;

//---STATIC ATTRIBUTES---
    
    /**
     * A reference to the single instance of this class
     */
    private static ReferenceManager _instance; 
}
Revision:	1.13
Committed:	Wed Mar 14 23:25:29 2001 UTC (23 years, 2 months ago) by tdb
Branch:	MAIN
Changes since 1.12:	+6 -6 lines
Log Message:	The whole server package structure has been changed. Old Package: uk.ac.ukc.iscream.* New Package: uk.org.iscream.*
#	User	Rev	Content
1	ajm	1.1	//---PACKAGE DECLARATION---
2	tdb	1.13	package uk.org.iscream.componentmanager;
3	ajm	1.1
4			//---IMPORTS---
5			import org.omg.CORBA.ORB;
6			import org.omg.CosNaming.*;
7			import org.omg.PortableServer.*;
8	tdb	1.13	import uk.org.iscream.core.*;
9			import uk.org.iscream.util.*;
10	ajm	1.1
11			/**
12			* This class returns references for global system objects.
13			* This class is used to create and return references to objects
14			* that are required throughout the system. Most of which
15	ajm	1.2	* are CORBA based. It also manages the ORB for the component.
16	ajm	1.1	*
17			* It is a singleton object with a static method to obtain a
18			* reference to it. This removes the need for passing
19			* references to all the objects it contains throughout
20			* a component.
21			*
22	ajm	1.12	* @author $Author: ajm4 $
23	tdb	1.13	* @version $Id: ReferenceManager.java,v 1.12 2001/02/23 16:55:12 ajm4 Exp $
24	ajm	1.1	*/
25			public class ReferenceManager {
26
27			//---FINAL ATTRIBUTES---
28
29			/**
30			* The current CVS revision of this class
31			*/
32	tdb	1.13	public final String REVISION = "$Revision: 1.12 $";
33	ajm	1.1
34			//---STATIC METHODS---
35
36			/**
37			* This returns a reference to the single instance of the
38			* ReferenceManager.
39			*
40	ajm	1.6	* This creates the single instance of the ReferenceManager
41			* if it does not exist by calling the private constructor.
42			*
43	ajm	1.1	* @return a reference to the ReferenceManager
44			*/
45	ajm	1.6	public static ReferenceManager getInstance() {
46	ajm	1.1	if (_instance == null) {
47	ajm	1.6	_instance = new ReferenceManager();
48	ajm	1.1	}
49			return _instance;
50			}
51
52			//---CONSTRUCTORS---
53
54			/**
55			* This is a private constructor
56			* This ensures that the system performs according to a Singleton design pattern
57	ajm	1.6	*/
58			private ReferenceManager() {
59			_orb = ORB.init(new String[] {}, null);
60			}
61	ajm	1.1
62			//---PUBLIC METHODS---
63
64			/**
65	ajm	1.2	* Obtains a CORBA reference through the naming service
66			* for the named object.
67	ajm	1.7	* Calls the dieWithError() if any exceptions happen!
68	ajm	1.2	*
69			* @param name the name of the CORBA object to resolve
70			*
71			* @return a reference to the object
72			*/
73			public org.omg.CORBA.Object getCORBARef(String name) {
74			org.omg.CORBA.Object objRef = null;
75			try {
76			objRef = getNS().resolve(getNS().to_name(name));
77			} catch (org.omg.CosNaming.NamingContextPackage.CannotProceed e) {
78	ajm	1.6	dieWithError("\nCRITICAL:Naming Service Cannot Proceed - when resolving reference to " + name + "!\n" +
79	ajm	1.5	" Please check with your CORBA naming service provider.");
80	ajm	1.2	} catch (org.omg.CosNaming.NamingContextPackage.InvalidName e) {
81	ajm	1.6	dieWithError("\nCRITICAL:Invalid Name - when resolving reference to " + name + "!\n" +
82	ajm	1.5	" Please check with your CORBA naming service provider.");
83	ajm	1.2	} catch (org.omg.CosNaming.NamingContextPackage.NotFound e) {
84	ajm	1.12	recoverWithError("\nCRITICAL:Not Found - when resolving reference to " + name + "!\n" +
85	ajm	1.5	" Please check that this component is running.");
86	ajm	1.2	}
87			return objRef;
88			}
89
90			/**
91			* Binds a given servant with the given name
92			* to the naming service.
93	ajm	1.7	* Calls the dieWithError() if any exceptions happen!
94	ajm	1.2	*
95			* @param objRef a reverence to the servant object
96			* @param name the name to bind to the naming service with
97			*/
98			public void bindToOrb(org.omg.PortableServer.Servant objRef, String name) {
99			try {
100			getNS().bind(getNS().to_name(name), getRootPOA().servant_to_reference(objRef));
101			} catch (org.omg.PortableServer.POAPackage.WrongPolicy e) {
102	ajm	1.6	dieWithError("\nCRITICAL:Wrong POA Policy - when binding " + name + "!\n" +
103	ajm	1.5	" This indicates an error with your ORB.");
104	ajm	1.2	} catch (org.omg.PortableServer.POAPackage.ServantNotActive e) {
105	ajm	1.6	dieWithError("\nCRITICAL:ServantNotActive - when binding " + name + "!\n" +
106	ajm	1.5	" This indicates an error with your ORB.");
107	ajm	1.2	} catch (org.omg.CosNaming.NamingContextPackage.InvalidName e) {
108	ajm	1.6	dieWithError("\nCRITICAL:Invalid Name - when binding " + name + "!\n" +
109	ajm	1.5	" Please check with your CORBA naming service provider.");
110	ajm	1.2	} catch (org.omg.CosNaming.NamingContextPackage.CannotProceed e) {
111	ajm	1.6	dieWithError("\nCRITICAL:Naming Service Cannot Proceed - when binding " + name + "!\n" +
112	ajm	1.5	" Please check with your CORBA naming service provider.");
113	ajm	1.2	} catch (org.omg.CosNaming.NamingContextPackage.NotFound e) {
114	ajm	1.12	recoverWithError("\nCRITICAL:Naming Service Not Found - when binding " + name + "!\n" +
115	ajm	1.5	" Please check with your CORBA naming service provider.");
116	ajm	1.2	} catch (org.omg.CosNaming.NamingContextPackage.AlreadyBound e) {
117	ajm	1.6	dieWithError("\nCRITICAL:Already Bound - when binding " + name + "!\n" +
118	ajm	1.5	" Another component with this name is already running.");
119	ajm	1.2	}
120			}
121
122			/**
123			* Activates the POA
124	ajm	1.7	* Calls the dieWithError() if any exceptions happen!
125	ajm	1.2	*/
126			public void activatePOA() {
127			try {
128			getRootPOA().the_POAManager().activate();
129			} catch (org.omg.PortableServer.POAManagerPackage.AdapterInactive e) {
130	ajm	1.6	dieWithError("\nCRITICAL:POA Set Inactive - when trying to activate POA!\n" +
131	ajm	1.5	" This indicates an error with your ORB.");
132	ajm	1.2	}
133			}
134
135			/**
136	ajm	1.1	* Overrides the {@link java.lang.Object#toString() Object.toString()}
137			* method to provide clean logging (every class should have this).
138			*
139	tdb	1.13	* This uses the uk.org.iscream.util.NameFormat class
140	ajm	1.6	* to format the toString()
141			*
142	ajm	1.1	* @return the name of this class and its CVS revision
143			*/
144			public String toString() {
145	ajm	1.6	return FormatName.getName(
146	ajm	1.7	_name,
147			getClass().getName(),
148	ajm	1.6	REVISION);
149	ajm	1.1	}
150
151			//---PRIVATE METHODS---
152
153	ajm	1.6	/**
154			* If there are any CORBA errors this method is called with the
155			* error message.
156			*
157	ajm	1.11	* The exception this throws is generic to CORBA communication
158			* problems, this is a Runtime exception and is typically only
159			* explicitly caught in the ComponentManager for the current VM
160			* The ComponentManager can then decide what course of action to
161			* take.
162	ajm	1.6	*
163	ajm	1.11	* Also, if it can, it will log the message with the logger.
164	ajm	1.6	*
165			* @param message the error message to die with
166			*/
167	ajm	1.12	private void recoverWithError(String message) throws ComponentCORBAException {
168	ajm	1.6	if (_logger != null) {
169	ajm	1.11	_logger.write(toString(), Logger.WARNING, "component CORBA error - " + message);
170	ajm	1.6	}
171	ajm	1.11	throw new ComponentCORBAException(message);
172	ajm	1.6	}
173	ajm	1.12
174
175			/**
176			* If there are any CORBA errors this method is called with the
177			* error message.
178			*
179			* Currently this prints the error, on the local err stream. Will
180			* print to the logger if one is available.
181			*
182			* ANY CALLS TO THIS METHOD CAUSE
183			* THE SYSTEM TO EXIT WITH A NON
184			* ZERO CODE!
185			*
186			* @param message the error message to die with
187			*/
188			private void dieWithError(String message) {
189			System.err.println(message);
190			if (_logger != null) {
191			_logger.write(toString(), Logger.FATAL, message);
192			}
193			System.exit(1);
194			}
195
196
197	ajm	1.6
198	ajm	1.1	//---ACCESSOR/MUTATOR METHODS---
199
200			/**
201			* Returns a reference to the ORB
202			*
203			* @return the reference this class holds
204			*/
205			public ORB getORB() {
206			return _orb;
207			}
208
209			/**
210			* Returns a reference to the Root POA
211	ajm	1.7	* Calls the dieWithError() if any exceptions happen!
212	ajm	1.1	*
213			* @return the reference this class holds
214			*/
215			public POA getRootPOA() {
216			if (_rootPOA == null) {
217			org.omg.CORBA.Object objRef = null;
218			try {
219			objRef = getORB().resolve_initial_references("RootPOA");
220			} catch (org.omg.CORBA.ORBPackage.InvalidName e) {
221	ajm	1.6	dieWithError("\nCRITICAL:Unable to resolve reference to the RootPOA!\n" +
222	ajm	1.5	" This indicates an error with your ORB.");
223	ajm	1.1	}
224			_rootPOA = POAHelper.narrow(objRef);
225			}
226			return _rootPOA;
227			}
228
229			/**
230			* Returns a reference to the Naming Service
231	ajm	1.7	* Calls the dieWithError() if any exceptions happen!
232	ajm	1.1	*
233			* @return the reference this class holds
234			*/
235			public NamingContextExt getNS() {
236			if (_ns == null) {
237			org.omg.CORBA.Object objRef = null;
238			try {
239			objRef = getORB().resolve_initial_references("NameService");
240			} catch (org.omg.CORBA.ORBPackage.InvalidName e) {
241	ajm	1.6	dieWithError("\nCRITICAL:Unable to resolve reference to the Naming Service!\n" +
242	ajm	1.5	" Please check with your CORBA naming service provider.");
243	ajm	1.1	}
244			_ns = NamingContextExtHelper.narrow(objRef);
245			}
246	ajm	1.5	// check we managed to talk to the naming service
247			if (_ns == null) {
248	ajm	1.6	dieWithError("\nCRITICAL:Unable to resolve reference to the Naming Service!\n" +
249	ajm	1.5	" Please check with your CORBA naming service provider.");
250			}
251	ajm	1.1	return _ns;
252			}
253
254			/**
255			* Returns a reference to the configuration manager
256	ajm	1.7	* Calls the dieWithError() if any exceptions happen!
257	ajm	1.1	*
258			* @return the reference this class holds
259			*/
260			public ConfigurationManager getCM() {
261			if (_cm == null) {
262	ajm	1.2	_cm = ConfigurationManagerHelper.narrow(getCORBARef("iscream.ConfigurationManager"));
263	ajm	1.1	}
264	ajm	1.5	// check we managed to talk to the configuration manager
265			if (_cm == null) {
266	ajm	1.6	dieWithError("\nCRITICAL:Unable to resolve reference to the Configuration Manager!\n" +
267	ajm	1.5	" Please check with your CORBA naming service provider.");
268			}
269	ajm	1.1	return _cm;
270			}
271
272			/**
273			* Returns a reference to the logger
274	ajm	1.5	* This will throw a Error if there is an error
275	ajm	1.1	*
276			* @return the reference this class holds
277			*/
278			public Logger getLogger() {
279			if (_logger == null) {
280	ajm	1.2	_logger = LoggerHelper.narrow(getCORBARef("iscream.Logger"));
281	ajm	1.1	}
282			return _logger;
283	ajm	1.4	}
284	ajm	1.1
285			//---ATTRIBUTES---
286
287			/**
288			* The ORB
289			*/
290			private ORB _orb;
291
292			/**
293			* The Naming Service
294			*/
295			private NamingContextExt _ns;
296
297			/**
298			* The Root POA
299			*/
300			private POA _rootPOA;
301
302			/**
303			* The configuration manager
304			*/
305			private ConfigurationManager _cm;
306
307			/**
308			* The logger
309			*/
310			private Logger _logger;
311
312			/**
313	ajm	1.7	* This is the friendly identifier of the
314			* component this class is running in.
315			* eg, a Filter may be called "filter1",
316			* If this class does not have an owning
317			* component, a name from the configuration
318			* can be placed here. This name could also
319			* be changed to null for utility classes.
320	ajm	1.1	*/
321	ajm	1.7	private String _name = null;
322	ajm	1.1
323			//---STATIC ATTRIBUTES---
324
325			/**
326			* A reference to the single instance of this class
327			*/
328			private static ReferenceManager _instance;
329			}