J2ee and web services
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The document discusses different Java platforms: - J2SE is for desktop/workstation applications, J2ME is for consumer devices, and J2EE is for server applications. - J2EE supports technologies like XML, web applications, web services, and defines APIs like JAXP. It uses service technologies like JDBC and communication technologies like JMS. - The main J2EE components are EJBs, which are reusable software units containing business logic packaged as Java classes and XML files. There are session beans for single clients, entity beans for persistent data, and message-driven beans.
J2ee and web services
- 1. JAVA PLATFORMS •J2SE – Java 2 Standard Edition Java for the desktop / workstation • •J2ME – Java 2 Micro Edition Java for the consumer device •J2EE - Java 2 Enterprise Edition Java for the server
- 2. J2ee J2se J2me
- 3. J2EE Supports • Extensible Markup Language • Web Applications • Web Services Support / WSDL Standard Format • UDDI and ebXML Standard Formats • HTTP-SOAP Transport Protocol
- 4. •J2EE comes with a built in application server •J2EE defines Java API for XML Processing (JAXP) API for processing XML •Uses SAX and DOM standards
- 5. •J2EE does not specify the nature and structure of the runtime. •J2EE Container – capability of the runtime to manage application components. •J2EE APIs specifies the contract between the applications and the container.
- 6. Data JDBC RDBMS Client Application Logic JavaMail Web Container Mail Server HTML/ XML RMI Servlets JSPs J2EE RMI/IIOP JavaMail Application JDBC JNDI Server JMS IIOP JTA JAF Applet EJB Container CORBA Session Beans Entity Beans JNDI Client Applica- tion RMI/IIOP Directory Services JavaMail JDBC JNDI JMS JMS JTA JAF
- 7. •The Component technologies – to hold the business logic. (JSP, Servlets and EJB) •The Service technologies – to provide supported services to application components (JDBC, JTA, JNDI) •The Communication technologies – transparent to appln programmer, provide the mechanism for communication among different parts of the appln. (JMS, JavaMail, RMI-IIOP) •They are re-usable software units containing business logic. • An EJB is just a collection of Java classes and an XML file, bundled into a single unit.
- 8. • They are re-usable software units containing business logic. • An EJB is just a collection of Java classes and an XML file, bundled into a single unit. • Java classes must follow certain rules and provide certain callback methods.
- 9. • Session Beans • Entity Beans • Message-driven Beans
- 10. • Intended for the use of a single client. • Lifespan is limited to that of its client. • When the client leaves the web site or the application is shut down, the session bean disappears.
- 11. Can keep information on behalf of its client across method calls. For example, Full information of the client is stored in every transactions example , credit card
- 12. • This bean implements a particular business logic, though its created for a particular client, it doesn’t have to remember anything about the client. • Can be considered as a remote procedure that gets executed on behalf of the client, taking some parameters and returns the result (of calculation in a particular business rule context).
- 13. •Persistence is its basic property. •It stays around even after the program is terminated until it is deleted. •When the program is restarted, it can gain access to this bean again. •It can be used by any program on the network. •It is executed remotely. •It is identified by a primary key. •Its nothing but the object representation of records in RDBMS tables.
- 14. Advantages • J2EE provides a complete architecture for developing - Distributed systems including object persistence, session tracking, transaction management, … •Separation of technical and application-specific code - Deployment descriptors - Container Managed Persistence
- 15. Disadvantages • Very complex technology Even simple examples require many interfaces, bean classes, deployment descriptors. • Many errors occur only at runtime (several steps required until the application is running) - Compilation - Packaging - Deployment - Running the application
- 16. A Web Application Framework (WAF) is a reusable, skeletal, semi-complete modular platform that can be specialized to produce custom web applications , which commonly serve the web browsers via the Http's protocol. WAF usually implements the Model-View-Controller (MVC) design pattern, typically in the Model 2 architecture to develop request-response web-based applications on the Java EE and .NET models.
- 18. Request-based Framework : Struts WebWork Beehive , Stripes Component-based Framework Jave Server Faces (JSF) Tapestry Wicket Hybrid – Meta Framework RIFE Spring Framework RIA-based Framework DWR Echo2 JSON-RPC-Java