Enterprise JavaBeans (EJB) is an API specification for building scalable, distributed, component-based, multi-tier applications. It leverages and extends the JavaBeans component model to provide a rich object-oriented transactional environment for developers building enterprise applications.
Enterprise JavaBeans (EJB) technology is the basis of Java 2 Platform, Enterprise Edition (J2EE). EJB technology provides the scalable architecture for executing business logic in a distributed computing environment. J2EE makes the life of an enterprise developer easier by combining the EJB component architecture with other enterprise technologies to solutions on the Java platform for seamless development and deployment of server side applications.
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Ques 22. What are the properties of java beans?
The JavaBeans specification defines the following types of bean properties:
► Simple: A bean property with a single value whose changes are independent of changes in any other property.
► Indexed: A bean property that supports a range of values instead of a single value.
► Bound: A bean property for which a change to the property results in a notification being sent to some other bean.
► Constrained: A bean property for which a change to the property results in validation by another bean. The other bean may reject the change if it is not appropriate.
Bean properties can also be classified as follows:
► Writable: A bean property that can be changed:
► ► Standard
► ► Expert
► ► Preferred
► Read Only: A bean property that cannot be changed.
► Hidden: A bean property that can be changed. However, these properties are not disclosed with the BeanInfo class
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Ques 23. What is the InfoBus?
The InfoBus is a compact Java API which allows cooperating applets or Beans, on a Web page or in any other Java application, to communicate data to one another. The InfoBus architecture enables Beans to be categorized as "data providers" and "data consumers". Data providers are Beans whose primary function is to access data from their native store, such as a DBMS, spreadsheet, flat file, Lotus Notes database etc., and to offer data onto the InfoBus.
Data consumers retrieve data from the bus, for analysis or visual display. This segregation of provider from consumer is extremely powerful in that it enables applications to be independent of their data; for example, a charting Bean need not understand SQL or JDBC in order to access DBMS data.
Of course, a Bean can be both a consumer and provider: for example a spreadsheet may accept data from a DBMS and provide data to a chart Bean.
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Ques 24. Does the InfoBus compete with JavaBeans?
On the contrary, InfoBus extends the power of JavaBeans to a new range of more dynamic applications. InfoBus is fully compatible with JavaBeans, and Lotus enthusiastically supports JavaBeans as the component standard for Java. Wherever possible, InfoBus uses the existing mechanisms of JavaBeans.
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Ques 25. Is InfoBus easy to use?
Using InfoBus aware components, such as the ESuite components from Lotus, users can easily construct powerful data driven applications. No programming or scripting is required: simple parameters are used to establish connections to databases and to select data for processing. For developers creating InfoBus components, InfoBus offers a straightforward API compatible in style with other features of JavaBeans.