OpBean


1   /**
2    * JOnAS: Java(TM) Open Application Server
3    * Copyright (C) 1999-2004 Bull S.A.
4    * Contact: jonas-team@objectweb.org
5    *
6    * This library is free software; you can redistribute it and/or
7    * modify it under the terms of the GNU Lesser General Public
8    * License as published by the Free Software Foundation; either
9    * version 2.1 of the License, or any later version.
10   *
11   * This library is distributed in the hope that it will be useful,
12   * but WITHOUT ANY WARRANTY; without even the implied warranty of
13   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14   * Lesser General Public License for more details.
15   *
16   * You should have received a copy of the GNU Lesser General Public
17   * License along with this library; if not, write to the Free Software
18   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
19   * USA
20   *
21   * Initial developer(s): ____________________________________.
22   * Contributor(s): ______________________________________.
23   *
24   * --------------------------------------------------------------------------
25   * $Id: OpBean.java,v 1.7 2004/04/19 06:39:29 benoitf Exp $
26   * --------------------------------------------------------------------------
27   */
28  
29  package sb;
30  
31  import javax.ejb.EJBException;
32  import javax.ejb.SessionBean;
33  import javax.ejb.SessionContext;
34  import javax.ejb.SessionSynchronization;
35  import javax.naming.InitialContext;
36  import javax.naming.NamingException;
37  
38  /**
39   * This is an example of Session Bean, statefull, and synchronized.
40   * @author JOnAS team
41   */
42  public class OpBean implements SessionBean, SessionSynchronization {
43  
44      /**
45       * Actual state of the bean
46       */
47      private int total = 0;
48  
49      /**
50       * value inside Tx, not yet committed.
51       */
52      private int newtotal = 0;
53  
54      /**
55       * User client
56       */
57      private String clientUser = null;
58  
59  
60      /* ========================= ejbCreate methods ============================ */
61  
62      /**
63       * There must be one ejbCreate() method per create() method on the Home
64       * interface, and with the same signature.
65       * @param user the user name
66       */
67      public void ejbCreate(String user) {
68  
69          total = 0;
70          newtotal = total; // in case we are outside transactions
71          clientUser = user;
72      }
73  
74      /*
75       * ====================== javax.ejb.SessionBean implementation
76       * =================
77       */
78  
79      /**
80       * The activate method is called when the instance is activated from its
81       * "passive" state. The instance should acquire any resource that it has
82       * released earlier in the ejbPassivate() method. This method is called with
83       * no transaction context.
84       * @throws EJBException Thrown by the method to indicate a failure caused by
85       *         a system-level error.
86       * @throws java.rmi.RemoteException This exception is defined in the method
87       *         signature to provide backward compatibility for enterprise beans
88       *         written for the EJB 1.0 specification. Enterprise beans written
89       *         for the EJB 1.1 specification should throw the
90       *         javax.ejb.EJBException instead of this exception. Enterprise
91       *         beans written for the EJB2.0 and higher specifications must throw
92       *         the javax.ejb.EJBException instead of this exception.
93       */
94      public void ejbActivate() throws EJBException, java.rmi.RemoteException {
95          // Nothing to do for this simple example
96      }
97  
98      /**
99       * The passivate method is called before the instance enters the "passive"
100      * state. The instance should release any resources that it can re-acquire
101      * later in the ejbActivate() method. After the passivate method completes,
102      * the instance must be in a state that allows the container to use the Java
103      * Serialization protocol to externalize and store away the instance's
104      * state. This method is called with no transaction context.
105      * @throws EJBException Thrown by the method to indicate a failure caused by
106      *         a system-level error.
107      * @throws java.rmi.RemoteException This exception is defined in the method
108      *         signature to provide backward compatibility for enterprise beans
109      *         written for the EJB 1.0 specification. Enterprise beans written
110      *         for the EJB 1.1 specification should throw the
111      *         javax.ejb.EJBException instead of this exception. Enterprise
112      *         beans written for the EJB2.0 and higher specifications must throw
113      *         the javax.ejb.EJBException instead of this exception.
114      */
115     public void ejbPassivate() throws EJBException, java.rmi.RemoteException {
116         // Nothing to do for this simple example
117     }
118 
119     /**
120      * A container invokes this method before it ends the life of the session
121      * object. This happens as a result of a client's invoking a remove
122      * operation, or when a container decides to terminate the session object
123      * after a timeout. This method is called with no transaction context.
124      * @throws EJBException Thrown by the method to indicate a failure caused by
125      *         a system-level error.
126      * @throws java.rmi.RemoteException This exception is defined in the method
127      *         signature to provide backward compatibility for enterprise beans
128      *         written for the EJB 1.0 specification. Enterprise beans written
129      *         for the EJB 1.1 specification should throw the
130      *         javax.ejb.EJBException instead of this exception. Enterprise
131      *         beans written for the EJB2.0 and higher specifications must throw
132      *         the javax.ejb.EJBException instead of this exception.
133      */
134     public void ejbRemove() throws EJBException, java.rmi.RemoteException {
135         // Nothing to do for this simple example
136     }
137 
138     /**
139      * Set the associated session context. The container calls this method after
140      * the instance creation. The enterprise Bean instance should store the
141      * reference to the context object in an instance variable. This method is
142      * called with no transaction context.
143      * @param sessionContext A SessionContext interface for the instance.
144      * @throws EJBException Thrown by the method to indicate a failure caused by
145      *         a system-level error.
146      * @throws java.rmi.RemoteException This exception is defined in the method
147      *         signature to provide backward compatibility for applications
148      *         written for the EJB 1.0 specification. Enterprise beans written
149      *         for the EJB 1.1 specification should throw the
150      *         javax.ejb.EJBException instead of this exception. Enterprise
151      *         beans written for the EJB2.0 and higher specifications must throw
152      *         the javax.ejb.EJBException instead of this exception.
153      */
154     public void setSessionContext(SessionContext sessionContext) throws EJBException, java.rmi.RemoteException {
155 
156     }
157 
158     /*
159      * ============== javax.ejb.SessionSynchronization implementation
160      * =============
161      */
162 
163     /**
164      * The afterBegin method notifies a session Bean instance that a new
165      * transaction has started, and that the subsequent business methods on the
166      * instance will be invoked in the context of the transaction. The instance
167      * can use this method, for example, to read data from a database and cache
168      * the data in the instance fields. This method executes in the proper
169      * transaction context.
170      * @throws EJBException Thrown by the method to indicate a failure caused by
171      *         a system-level error.
172      * @throws java.rmi.RemoteException - This exception is defined in the
173      *         method signature to provide backward compatibility for enterprise
174      *         beans written for the EJB 1.0 specification. Enterprise beans
175      *         written for the EJB 1.1 and higher specifications should throw
176      *         the javax.ejb.EJBException instead of this exception. Enterprise
177      *         beans written for the EJB 2.0 and higher specifications must not
178      *         throw the java.rmi.RemoteException.
179      */
180     public void afterBegin() throws EJBException, java.rmi.RemoteException {
181         newtotal = total;
182     }
183 
184     /**
185      * The beforeCompletion method notifies a session Bean instance that a
186      * transaction is about to be committed. The instance can use this method,
187      * for example, to write any cached data to a database. This method executes
188      * in the proper transaction context. <b>Note: </b> The instance may still
189      * cause the container to rollback the transaction by invoking the
190      * setRollbackOnly() method on the instance context, or by throwing an
191      * exception.
192      * @throws EJBException Thrown by the method to indicate a failure caused by
193      *         a system-level error.
194      * @throws java.rmi.RemoteException - This exception is defined in the
195      *         method signature to provide backward compatibility for enterprise
196      *         beans written for the EJB 1.0 specification. Enterprise beans
197      *         written for the EJB 1.1 and higher specifications should throw
198      *         the javax.ejb.EJBException instead of this exception. Enterprise
199      *         beans written for the EJB 2.0 and higher specifications must not
200      *         throw the java.rmi.RemoteException.
201      */
202     public void beforeCompletion() throws EJBException, java.rmi.RemoteException {
203         // Nothing to do for this simple example
204 
205         // We can access the bean environment everywhere in the bean,
206         // for example here!
207         try {
208             InitialContext ictx = new InitialContext();
209             String value = (String) ictx.lookup("java:comp/env/prop1");
210             // value should be the one defined in ejb-jar.xml
211         } catch (NamingException e) {
212             throw new EJBException(e);
213         }
214     }
215 
216     /**
217      * The afterCompletion method notifies a session Bean instance that a
218      * transaction commit protocol has completed, and tells the instance whether
219      * the transaction has been committed or rolled back. This method executes
220      * with no transaction context.
221      * @param committed - True if the transaction has been committed, false if
222      *        is has been rolled back.
223      * @throws EJBException Thrown by the method to indicate a failure caused by
224      *         a system-level error.
225      * @throws java.rmi.RemoteException - This exception is defined in the
226      *         method signature to provide backward compatibility for enterprise
227      *         beans written for the EJB 1.0 specification. Enterprise beans
228      *         written for the EJB 1.1 and higher specifications should throw
229      *         the javax.ejb.EJBException instead of this exception. Enterprise
230      *         beans written for the EJB 2.0 and higher specifications must not
231      *         throw the java.rmi.RemoteException.
232      */
233     public void afterCompletion(boolean committed) throws EJBException, java.rmi.RemoteException {
234         if (committed) {
235             total = newtotal;
236         } else {
237             newtotal = total;
238         }
239     }
240 
241     /* ========================= Op implementation ============================ */
242 
243     /**
244      * Business method implementation.
245      * @param s nb of shares to be bought
246      */
247     public void buy(int s) {
248         newtotal = newtotal + s;
249         return;
250     }
251 
252     /**
253      * Business method implementation.
254      * @return the nb of shares bought
255      */
256     public int read() {
257         return newtotal;
258     }
259 }
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