Java™ Application Development on Linux - Dator

480Chapter 21Introduction to Enterprise JavaBeansdepend many factors, including the databases your container supports, thecomplexity of your database, the quantity of non-Java clients, or the amountof legacy code.Entity beans can be a hard sell in many development environments. Wecan see three strong reasons to resist the use of entity beans.1. Heterogenous environments. In many enterprises, rich and diverse setsof development environments exist—Windows.NET and ASP clients,mainframe clients, C and C++ applications, third-party applications, andJava. The solution many database environments adopt is to use storedprocedures that are shared across all of these platforms to concentratedatabase access into a common set of code. Stored procedures do not tendto be written with the kind of strict row-to-object mapping that entitybeans model so well; instead, they are often designed to support specificbusiness processes. That fits so well with the session bean model that youmay be tempted to implement a session bean facade in front of such storedprocedures and leave it at that.2. Legacy code. A variation on the above argument exists when there is alreadya considerable body of code, perhaps even Java code written directlyusing JDBC, that accesses the database and performs the common operations.Here again, the simplest solution is to put a session bean facade onthe already existing code.3. Mobile cheese. One of the trendy business books published recently is titledWho Moved My Cheese? and it is about the negative ways in whichpeople react to change. You might very well meet resistance simply becausethe technology is new and unfamiliar, and represents a change in thinkingabout data persistence from what the development staff is used to doing.So, where is it suitable? Entity beans are particularly well suited to environmentsthat are homogenous by being based either mostly on Java or onCORBA/IIOP. Further, they are well suited to environments where the bulkof the work is the editing and manipulation of small numbers of entities persession, as opposed to large reports or statistical queries where a session mightwant to use many or all rows in a table.Please note that using entity beans in such appropriate cases in no wayprecludes other types of use! You just won’t likely use entity beans for them.In other words, you don’t have to use it just because it is there.