The concepts

The context encapsulates all common data and services in one object and provides access to information that is usually defined as singletons or static data.

All JViews TGO components can access contextual information from this single entry point called the context. In JViews TGO this idea of application context is similar to the Java™ BeansContext as defined in “Extensible Runtime Containment and Service Protocol for JavaBeans™”. (For more information, see http://java.sun.com.) However, you do not have to be familiar with the BeansContext API to understand the concept of context in JViews TGO.

The context is defined by the IlpContext interface. This interface allows you to retrieve contextual information such as the locale and properties, as well as a number of services that are more than simple information providers. These services are the following:

These services are described in detail in section The context services.

Generally, there is only one context per application. However, you can define multiple contexts if your application is to run in a multiuser environment or if different services should be accessible from various parts of the application. For more information, see Creating a new context.

The deployment descriptor is an XML file used to initialize an application context. It is tagged with the XML element <deployment> . The context data and services to be initialized when the application is launched are defined between the opening and closing tags.

The deployment descriptor represents an easier and faster alternative for configuring a context than the API, as you do not have to write a single line of code nor recompile when you make a change.

For details on how to write and load a deployment descriptor, see Writing a deployment descriptor and How to load a deployment descriptor using the parse method.