TxSupports


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43   * $Id: TxSupports.java 1912 2005-06-16 22:29:56Z jlaskowski $
44   */
45  package org.openejb.core.transaction;
46  
47  import javax.ejb.EnterpriseBean  ;
48  
49  import org.openejb.ApplicationException;
50  
51  /**
52   * 17.6.2.3 Supports
53   * 
54   * The Container invokes an enterprise Bean method whose transaction attribute
55   * is set to Supports as follows.
56   * 
57   * � If the client calls with a transaction context, the Container performs 
58   *   the same steps as described in the Required case.
59   * 
60   * � If the client calls without a transaction context, the Container performs
61   *   the same steps as described in the NotSupported case.
62   * 
63   * The Supports transaction attribute must be used with caution. This is 
64   * because of the different transactional semantics provided by the two 
65   * possible modes of execution. Only the enterprise beans that will
66   * execute correctly in both modes should use the Supports transaction 
67   * attribute.
68   * 
69   * @author <a HREF="mailto=david.blevins@visi.com">David Blevins</a>
70   * @version $Revision: 1912 $ $Date: 2005-06-16 15:29:56 -0700 (Thu, 16 Jun 2005) $
71   */
72  public class TxSupports extends TransactionPolicy {
73      
74      public TxSupports(TransactionContainer container){
75          this();
76          this.container = container;
77      }
78  
79      public TxSupports(){
80          policyType = Supports;
81      }
82      
83      public String   policyToString() {
84          return "TX_Supports: ";
85      }
86      
87      public void beforeInvoke(EnterpriseBean   instance, TransactionContext context) throws org.openejb.SystemException, org.openejb.ApplicationException{
88          
89          try {
90          
91              context.clientTx  = getTxMngr().getTransaction();
92              context.currentTx = context.clientTx;
93          
94          } catch ( javax.transaction.SystemException   se ) {
95              throw new org.openejb.SystemException(se);
96          }
97      }
98  
99      public void afterInvoke(EnterpriseBean   instance, TransactionContext context) throws org.openejb.ApplicationException, org.openejb.SystemException{
100 
101     }
102 
103     /**
104      * <B>Container's action</B>
105      * 
106      * <P>
107      * Re-throw AppException
108      * </P>
109      * 
110      * <B>Client's view</B>
111      * 
112      * <P>
113      * Client receives AppException.  Can attempt to continue computation in the
114      * transaction, and eventually commit the transaction (the commit would fail
115      * if the instance called setRollbackOnly()).
116      * </P>
117      */
118     public void handleApplicationException( Throwable   appException, TransactionContext context) throws ApplicationException{
119         // [1] Re-throw AppException
120         throw new ApplicationException( appException );
121     }
122     
123     /**
124      * A system exception is any exception that is not an Application Exception.
125      * <BR>
126      * <B>Container's action</B>
127      * 
128      * <P>
129      * <OL>
130      * <LI>
131      * Log the exception or error so that the System Administrator is alerted of
132      * the problem.
133      * </LI>
134      * <LI>
135      * Mark the transaction for rollback.
136      * </LI>
137      * <LI>
138      * Discard instance.  The Container must not invoke any business methods or
139      * container callbacks on the instance.
140      * </LI>
141      * <LI>
142      * Throw javax.transaction.TransactionRolledbackException to remote client;
143      * throw javax.ejb.TransactionRolledbackLocalException to local client.
144      * </LI>
145      * </OL>
146      * 
147      * </P>
148      * 
149      * <B>Client's view</B>
150      * 
151      * <P>
152      * Receives javax.transaction.TransactionRolledbackException or
153      * javax.ejb.TransactionRolledbackLocalException.
154      * 
155      * Continuing transaction is fruitless.
156      * </P>
157      */
158     public void handleSystemException( Throwable   sysException, EnterpriseBean   instance, TransactionContext context) throws org.openejb.ApplicationException, org.openejb.SystemException{
159         
160         
161         boolean runningInTransaction = ( context.currentTx != null );
162 
163         if (runningInTransaction) {
164             /* [1] Log the system exception or error *********/
165             logSystemException( sysException );
166             
167             /* [2] Mark the transaction for rollback. ********/
168             markTxRollbackOnly( context.currentTx );
169             
170             /* [3] Discard instance. *************************/
171             discardBeanInstance(instance, context.callContext);
172             
173             /* [4] TransactionRolledbackException to client **/
174             throwTxExceptionToServer( sysException );
175         
176         } else {
177             /* [1] Log the system exception or error *********/
178             logSystemException( sysException );
179 
180             /* [2] Discard instance. *************************/
181             discardBeanInstance( instance, context.callContext);
182 
183             /* [3] Throw RemoteException to client ***********/
184             throwExceptionToServer( sysException );
185         }
186 
187     }
188 
189 }
190 
191
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