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@Stateful @TransactionAttribute(TransactionAttributeType.NEVER) public class PlaceItemBean implements PlaceItem { @PersistenceContext(type = PersistenceContextType.EXTENDED) private EntityManager em; private Item item; private User seller; public Item createItem(Long userId, Map itemData) { // Load seller into conversation seller = em.find(User.class, userId); // Create item for conversation item = new Item(itemData, seller); user.addItem(item); return item; } public void addImage(String filename) { item.getImages().add(filename); } @Remove @TransactionAttribute(TransactionAttributeType.REQUIRED) public void submit() { em.persist(item); } }

To process the event, you need to execute a sequence of operations: check the winning bid for the auction, charge the cost of the auction, notify the seller and winner, and so on. You could write a single class that has one big procedure. A better design is to move the responsibility for each of these steps into reusable smaller components and to separate them by concern. We ll have much more to say about this in chapter 16. For now, assume that you followed our advice and that several classes need to be called inside the same unit of work to process the closing of an auction.

To use some persistence frameworks, such as EJBs, your application becomes dependent on that framework. Hibernate doesn t create this additional dependency. Persistent objects in your application don t have to inherit from a Hibernate class or obey specific semantics: You simply create your Java objects and the associated mapping documents. Persisting the application objects is then left to Hibernate. Also, unlike EJBs, Hibernate doesn t require a special container in order to function. Hibernate can be used in any application environment, from standalone applications to enterprise application servers. In the next section, you ll see that the functionality and ease provided by Hibernate don t come at the cost of limited support for objectoriented features.

3rd level, } <photo> else if(ev.level==2 and ev.qname.name == "photo") { def photo = FlickrPhoto { id: readAttrS(ev,"id"); farm: readAttrS(ev,"farm"); owner: readAttrS(ev,"owner"); secret: readAttrS(ev,"secret"); Create and store server: readAttrS(ev,"server"); photo object title: readAttrS(ev,"title"); isFamily: readAttrB(ev,"isfamily"); isFriend: readAttrB(ev,"isfriend"); isPublic: readAttrB(ev,"ispublic"); }; insert photo into photos; Didn t recognize } element else { println("{ev}"); }

The EntityManager has two different methods that allow you to find an entity by its primary key:

Message selectors are based on message properties, which are additional headers that can be assigned to a message; they allow vendors and developers to attach information to a message that isn t part of the message s body. The Message interface provides several methods for reading and writing properties. Properties can have a String value or one of several primitive values (boolean, byte, short, int, long, float, double). The naming of properties, together with their values and conversion rules, is strictly defined by JMS. Here s how a JMS producer would go about setting a MessageFormat property on a Message:

The PostScript output of this module is quite naive, and doesn t make use of the full functionality of PostScript. If this module were destined to be taken up in production, it would probably have a class method that would generate PostScript for the prologue defining a few named procedures that map exactly to the objects that you need to draw. Then, when the time comes to draw them, all you need to do is print the parameters, and the name of the defined procedure. This makes the module slightly easier to read, but more importantly, it makes your PostScript file much smaller.

<castormapping> Creates a Castor mapping.xml file. <jboss> <jrun> <mvcsoft> <orion> <pramati> <strutsform> <weblogic> <websphere> Produces jaws.xml and jboss.xml. Creates JRun-specific deployment descriptor. Generates MVCSoft configuration file. Creates Orion-specific deployment descriptor. Generates Pramati-specific deployment descriptor. Creates Struts form-bean source code from entity beans. Produces WebLogic-specific deployment descriptors. Generates WebSphere-specific deployment descriptors such as Schema.dbxmi.

Iterator l = items.iterator(); while (l.hasNext()) { Item item = (Item)l.next(); System.out.println("Id:" + item.getItemId() + " Initial Price:"+item.getInitialPrice()); }

An Enterprise JavaBean (EJB) client is any object that contacts an EJB. For this contact to work, EJBs need to know how to find each other. The recipes presented in this chapter provide solutions for allowing EJBs to locate one another. EJB clients can be divided into two main categories: remote clients and local clients. This is an important distinction because it affects the way clients find the EJBs they need to use. For example, creating the InitialContext instance to look up EJBs in the same virtual machine is completely different from creating an instance for remote EJB lookups. The clients covered in this chapter include JavaServer Pages (JSPs), servlets, applets, and other EJBs. Each client faces its own set of problems. In this chapter, you ll find recipes for the following tasks: