- The enterprise application is delivered to the client as a .ear file having a no of .jar files, settings, other libraries , deployment descriptors and other web resources.
- A deployment descriptor is an XML document with an .xml extension that describes the deployment settings of an application, a module, or a component.
- At runtime the J2EE container reads the deployment descriptors and acts upon the application, module or component accordingly.
- Two types of Deployment descriptor
- J2EE Deployment Descriptors:-Defined by the J2EE Specification. It can be used to configure settings for any J2EE compliant implementation.
- Runtime Deployment Descriptors: - It is used to configure J2EE implementation specific parameters.
- J2EE Deployment Descriptors:-Defined by the J2EE Specification. It can be used to configure settings for any J2EE compliant implementation.
The pattern is an organised way of solving some specific class of problems. These patterns come in to the picture at analysis and high-level-design phase. The first step of applying one pattern to the code base is first to understand the find the vector of change in the code base. Next step is to isolate the things that are subject to change form the things that are not. That is adding a layer of abstraction to the code. The goal of design patterns is isolating the changes in your code. Understand Inheritance and Composition as a solution to a specific class of problems. Inheritance : - It allows you to express differences in behavior (that's the thing that changes) in objects that all have the same interface (that's what stays the same). Composition : - Composition can also be considered a pattern, since it allows you to change—dynamically or statically—the objects that implement your class, and thus the way that class works. Some principles of designing the c...