1. Assignment of JAVA Email id : Engnr.shehzad@gmail.com BSSE-F10-M-10-JAVA1 Overview of J2EE/Session 2/Slide 1 of 38

2. Lecture 5 Technologies of J2EE By Mr. Muhammad Shehzad

3. Overview of J2EE/Session 2/Slide 3 of 38 Review Traditional enterprise application providers have changed over from 2-tier, client-server application models to three-tier application models. The rapid development of this new model was fuelled by the introduction of various middleware services. A developer is usually faced with a range of problems while developing an enterprise-wide application. The different problem domains include: Programming productivity Response to demand Integration with existing systems Freedom to choose Maintaining security  The mission of J2EE is to provide a platform-independent, portable, multi-user, secure and standard enterprise-class platform for server-side deployments written in the Java language.

4. Overview of J2EE/Session 2/Slide 4 of 38 Review Contd… The J2EE specifications include those to: Design the enterprise application Distribute Roles to people involved in developing the software (Project/Product) i.e. J2EE specifies the rules of engagement that people must agree on when writing enterprise software Bundle the files to the clientProgramming productivity Standardize the technologies that could be used in J2EE Standardize the interaction between the different technologies

5. Overview of J2EE/Session 2/Slide 5 of 38 Review Contd… The various J2EE components include: Application components Containers Resource manager drivers Databases The J2EE platform communicates with the outside world in different ways. These ways, known as contracts, are well defined, and separated into: APIs Network protocols Deployment descriptors One of the most important concepts in J2EE is a platform role. The J2EE standard provides separation between different roles, so that different players in the market can specialize in their role. These roles include: J2EE Product Provider Application Component Provider

6. Overview of J2EE/Session 2/Slide 6 of 38 Review Contd… One of the most important concepts in J2EE is a platform role. The J2EE standard provides separation between different roles, so that different players in the market can specialize in their role. These roles include: J2EE Product Provider Application Component Provider Application Assembler Deployer System Administrator Tool Provider The J2EE Platform provides several benefits such as: Simplified architecture and development Integrating existing enterprise information systems Scaling Security

7. Overview of J2EE/Session 2/Slide 7 of 38 The Objectives… Describe the various technologies involved in J2EE Explain the component technologies Discuss the service technologies Describe the communication technologies

8. Overview of J2EE/Session 2/Slide 8 of 38 J2EE Technologies categories Java Applets and Applications HTML XML Client-side Technology EJB Servlets JSP Component Technologies Service Technologies JDBC JNDI Java Transaction API Communication Technologies Internet Protocols RMI JMS JavaMail

9. Overview of J2EE/Session 2/Slide 9 of 38

10. Overview of J2EE/Session 2/Slide 10 of 38 Component Technologies Servlets JSP EJB JavaBeans

11. Overview of J2EE/Session 2/Slide 11 of 38 Servlets Server-side programs No interface Form basic building blocks of web applications Provide the means to extend and enhance web servers Can be used to generate dynamic content Server Client Servlet Applet

12. Overview of J2EE/Session 2/Slide 12 of 38 JSP (Java Server Pages) Extension of servlet technology Created to support authoring of HTML and XML pages Easier than servlets to combine static data with dynamic content More suited for separating application logic from presentation logic Server Client JSP Web Server Servlet invoked JSP Compiled by web server Result Returned

13. Overview of J2EE/Session 2/Slide 13 of 38 Enterprise JavaBeans Used to develop business logic Allow separation of app logic from system level services To use services provided by J2EE, business components are implemented by EJB components/Enterprise beans Server Middle Tier Client ----- System level services Application logic

14. Overview of J2EE/Session 2/Slide 14 of 38 Enterprise Beans Session Beans Entity Beans Used exclusively by clients that created them Stateful Stateless Client Does the tasks Bean destroyed Exists as long as session exists Client Does the tasks Bean exists Persists only as long as request is being processed Data Client Bean Wrapper for data easing access to data Instance of bean can be shared by multiple clients

15. Overview of J2EE/Session 2/Slide 15 of 38 Service Technologies Generally, containers take care of required J2EE services for components Developer focuses on business logic Sometimes services may need to be explicitly called Developer Components Develops SERVICES

16. Overview of J2EE/Session 2/Slide 16 of 38 Java Transaction API & Service Transaction Manager Java Transaction API Resource Manager Application Server Transactional Applications Components of Distributed Transaction System Java Transaction Service specifies the implementation of the Transaction Manager Most important component in a transaction processing environment Creates transactions requested by components, and performs 2-phase commit recovery protocol with Resource Managers

17. Overview of J2EE/Session 2/Slide 17 of 38 Transactions Group of operations performed on data Records Database TRANSACTION-------- ------- tomic onsistent solated urable

18. Overview of J2EE/Session 2/Slide 18 of 38 Request sent to Transaction Manager to initiate transaction Transaction Manager starts transaction & associates it with thread that initiated the process Transaction Manager creates transactional context - which is shared by all relevant components & threads Thread issues commit or rollback request Transaction Begins Transaction Ends

19. Overview of J2EE/Session 2/Slide 19 of 38 Component Service Communication Technologies Communication Technologies Communication Technologies

20. Overview of J2EE/Session 2/Slide 20 of 38 Internet Protocols Client Server Sends request Results sent Request processed Web-based, distributed, enterprise applications scenario

21. Overview of J2EE/Session 2/Slide 21 of 38 HTTP Set of rules for exchanging files on the World Wide Web

22. Overview of J2EE/Session 2/Slide 22 of 38 Internet TCP/IP TCP breaks up data into packets TCP assembles packets after checking for errors, missed packets etc. IP picks up packets, and ensures that they reach destination. TCP tracks the packets

23. Overview of J2EE/Session 2/Slide 23 of 38 SSL Data Encrypted Data SSL Encrypted data transmitted

24. Overview of J2EE/Session 2/Slide 24 of 38 Java Mail JavaMail Used to exchange messages between users Supports SMTP, POP, IMAP4 Slower than JMS

25. Overview of J2EE/Session 2/Slide 25 of 38 XML Internet XML For distributing structured information over the Internet Data interchange format in web- based applications--

26. Overview of J2EE/Session 2/Slide 26 of 38 The Power of XML ------ ----- XML Appropriate presentation style applied Same data can be presented in a variety of ways, to a variety of devices SQL Server Database Oracle Database XML Changes are updated to 2 different databases

27. Overview of J2EE/Session 2/Slide 27 of 38 HTMLXML ---- Fixed predefined tags Tags defined by developer ---- Handles content & presentation Browser interprets HTML code CSS Can be optionally used to take care of presentation Handles ONLY content XSL/CSS Transforms XML by applying styles to it

28. Overview of J2EE/Session 2/Slide 28 of 38 J2EE Technologies Client-Side Component Technologies Service Technologies Communication Technologies Servlets JSP JavaBeans EJB Session Beans Entity Beans JDBC Java Transaction API & Service JNDI Internet Protocols Other Protocols HTTP TCP/IP SSL RMI JMS JavaMail

29. Overview of J2EE/Session 2/Slide 29 of 38 Summary The J2EE technologies can be broadly classified into four different categories: Client-side technologies Component technologies Service technologies Communication technologies Component technologies include: Servlets Java Server Pages Enterprise JavaBeans Session Beans Entity Beans

30. Overview of J2EE/Session 2/Slide 30 of 38 Summary Service Technologies include: Java Database Connectivity Java Transaction API and Service Java Naming and Directory Interface Transaction - A transaction is a group of operations that are carried out as a single unit on records stored in a database. The group must have a set of characteristics in order to be considered as transactional. ACID properties include Atomic Consistent Isolated Durable

31. Overview of J2EE/Session 2/Slide 31 of 38 Summary Contd...  The Java Naming and Directory Interface, JNDI in short, is a naming service. A naming service associates a name with an object, so that clients can locate the object using the specified name. A directory service on the other hand, allows attributes as well as names to be associated with objects. Internet Protocols include: HTTP TCP/IP SSL

32. Overview of J2EE/Session 2/Slide 32 of 38 Summary Contd... Remote Object Protocols include: RMI and RMI-IIOP Java IDL JMS JavaMail XML or Extensible Markup Language is the most popular tool to distribute structured information over the Internet. XML is used for structured information management. XML can also be used to create customized views of data. XML documents come in two flavors – well formed and valid. J2EE deployment descriptors are written in XML based on predefined DTDs