Enterprise JavaBean

In simple cases, persistence can be achieved by a protocol by which a component instance serializes itself into a stream that is managed by its container. For larger, server-side components, each component can manage its own persistent storage and transactions effective composition now requires that the container be able to coordinate nested transactions that cross its subcomponent boundaries. Enterprise JavaBeans, CORBA, Microsoft Transaction Server, and COM+ provide their own versions of this... 

This is changing substantially, with mainframe applications reborn as server-side components using technologies such as Enterprise JavaBeans. 

The Enterprise JavaBeans model lets you implement business functions as JavaBeans and then plug them in to a standard container that provides automatic management of resources and contention from multiple threads, transaction programming based on two-phase commit across multiple independent components, and distributed programming. An EJB component, packaged into a JAR file, has four main parts. 

CORBA recently defined mappings for the Java language and aligned closely with Jav-aBeans and Enterprise JavaBeans for its component model. In fact, the Java Transaction Service is defined based on the CORBA model. 

The 1.0 specs of Enterprise JavaBeans are a good example of standard architectural patterns and how they can be used to define a simple and consistent architecture even for large-scale business systems. 

Some of these choices will be influenced by the technical architecture. For example, Enterprise JavaBeans does not like its components to implement multiple threads, because it tries to manage that at the level of the vendor-provided containers. 

Finally, the service-oriented paradigm is often associated with Web Services as the realizing technical infrastructure. This is not necessary [582], since other component technologies [991] like COM/DCOM [846, 847], CORBA [877], or Enterprise JavaBeans [504] are also applicable, as they implement the necessary concepts like (i) implementation transparency, (ii) location transparency, (iii) self-containment, and (iv) an explicit interface independent from its implementation. 

Anderson, G., Anderson, P. Enterprise JavaBeans Components Architecture. Prentice-HaU, Englewood Cliffs (2002)... 

Enterprise JavaBeans Specification 2.1, Sun Microsystems (2005). http //java.sun.com/ products/ejb/... 

The importance of software components for middleware is due to the fact that frequently, components are the basis for middleware implementation. From a historic perspective, the first commercial component models were COM [5] (from Microsoft) and JavaBeans [6]. These models evolved to. NET [7] and newer versions of Enterprise Java Beans (EJB) [8]. Some of the aforementioned middleware even included newer component-based extensions such as the CORBA Component Model (CCM) [9] in the case of CORBA. 

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