data matrix barcode generator java

data matrix code java generator

java data matrix barcode generator

java data matrix generator

java data matrix library,

java data matrix library,
java data matrix reader,

java data matrix,

java data matrix barcode,
java data matrix library,
data matrix barcode generator java,
java data matrix reader,
java data matrix reader,

java data matrix generator open source,
java data matrix barcode reader,
data matrix barcode generator java,
java data matrix barcode,
java data matrix library,
java data matrix decoder,
data matrix barcode generator java,
java data matrix,
java data matrix,
java data matrix reader,
java data matrix decoder,
java data matrix decoder,
java data matrix barcode reader,
java data matrix library,
java data matrix barcode generator,
data matrix barcode generator java,
java data matrix generator open source,
java data matrix,
java data matrix generator,
java data matrix generator open source,
java data matrix,

java data matrix generator open source,
java data matrix barcode,
java data matrix barcode reader,
data matrix code java generator,
java data matrix,
java data matrix barcode,
java data matrix barcode generator,
java data matrix generator,
java data matrix barcode generator,
java data matrix decoder,
java data matrix barcode reader,
java data matrix,
java data matrix generator open source,
data matrix barcode generator java,
data matrix barcode generator java,
java data matrix barcode generator,
java data matrix,
data matrix code java generator,
java data matrix,
java data matrix decoder,
java data matrix barcode reader,
java data matrix library,
java data matrix generator,
java data matrix barcode,
java data matrix reader,
java data matrix barcode,
java data matrix generator,
java data matrix reader,
java data matrix barcode reader,
java data matrix reader,
java data matrix decoder,
java data matrix generator,
java data matrix generator open source,
java data matrix reader,
java data matrix barcode reader,
java data matrix generator open source,
java data matrix barcode reader,
java data matrix library,
data matrix code java generator,
java data matrix reader,
java data matrix generator,
data matrix barcode generator java,
java data matrix generator open source,
data matrix barcode generator java,
java data matrix reader,
java data matrix,
data matrix code java generator,
java data matrix library,
java data matrix library,

Behind the scenes, the container takes care of several mechanical details to start listening for messages sent to the destination specified by the activation configuration properties. As soon as a message arrives at the destination, the container forwards it to an instance of the MDB.

163 private void releaseConnection() { 164 try { con.close(); } catch (SQLException ex) { 165 throw new EJBException("releaseConnection: " + ex.getMessage()); 166 } 167 } // releaseConnection 168 } // TxControllerEJB This sample, taken in its original form from the Duke s Bank implementation, contains a set of concerns that is interesting to modularize: It implements the SessionBean interface (lines 20 and 27). In the business method implementations (line 30), there is a recurrent call to the method checkArgsAndResolve (lines 36, 57, 59, 111). This call has two roles: it allows the use of a method to check certain preconditions on the arguments, and it resolves the reference of an account by using its Home interface. It defines and handles references to other EJBs (lines 123, 134, 135). It implements and uses some database functions (lines 100, 101, 107, 150). The original Duke s Bank implementation does not use any particular integration technique for persistence but directly uses the JDBC API. These concerns make the facade s code complicated and force the implementer to define private methods (line 95). These methods clarify the code; however, since they are ad hoc, their maintenance can be complex and error prone. We will come back to these points in the remainder of the chapter. As for now, we focus primarily on the problem of implementing the J2EE facade design pattern (as depicted by Sun Microsystems) independently from the EJB session (lines 20 and 27).

Instead of implementing a remote or local business interface, MDBs implement the javax.jms.MessageListener interface. The container uses this well-known JMS interface to invoke an MDB. The onMessage method defined by the interface has a single javax.jms.Message parameter that the container uses to pass a received message to the MDB. Believe it or not, this is more or less all you need to know to get by when using MDBs, as long as you have a decent understanding of messaging and JMS. This wraps up this chapter s discussion of the EJB 3 business-tier components. As we mentioned earlier, we ll devote the entirety of the next part of the book to this vital part of the EJB platform. For now, let s move on to the other major part of EJB, the Persistence API.

Creating a session bean like this one allows a client to create a process to execute business logic without having to stick around and wait for it to complete. The client merely invokes the startProcess() method. The startProcess() method accepts a Serializable object as arguments to the business process. When the startProcess() method returns, the client simply continues with other work. The timer started by the startProcess() method will eventually time out; the recipe sets it for 1 second and invokes the callback method on the session bean. The ejbTimeout() callback method contains the actual business logic for execution. The session bean pulls out any arguments from the Timer instance and executes the business logic. Using the timer service in this way enables you to create asynchronous processes without the use of JMS and message-driven beans.

The Java Persistence API (JPA) is the persistence-tier solution for the Java EE platform. Although a lot has changed in EJB 3 for session beans and MDBs, the changes in the persistence tier have truly been phenomenal. In fact, other than some naming patterns and concepts, JPA has very little in common with the EJB 2 entity bean model. JPA does not follow the container model (which is just not very