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Enterprise computing Unit I notes
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Unit I - Enterprise Computing 3rd Year B.Sc., C.S.UNIT 1J2EE & J2SE: J2EE Multi-tier Architecture Distributive Systems The Tier J2EE Multi tier Architecture Client tier implementation Web Tier Implementation EJB Tier Implementation EIS Tier Implementation Challenges J2EE BEST PRACTICES: Enterprise Application Strategy The Enterprise Application Clients Sessions Management Web tier and Java Server Pages*************************************************************************Multi tier Architecture: A clients request to a server generates requests to another server that are connected together through a backbone network. Eg. You asking a travel agent to arrange your vacation.The 3 editions of Java are: 1. J2SE API needed to built a Java app/applet2. J2ME API used to create wireless Java Apps.3. J2EE API to build apps for multi-tier architecture
The birth of J2EE: CGI technology consisted of a program that was callable by a browser whenever the link / action from web occurs CGI uses the users data to retrieve the account information from a database. Java Servlets addresses the problem of CGI Tech. Java Servlets consists of Java classes, data and methods which are callable by a browser similar to how a browser calls a CGI program. Java was used for all coding in Java Servlet and HTML code was used only in output statements that were sent to the browser ( So JSP was developed) JSP is written in HTML with snippets of Java Code intermingled. JSP is then automatically translated into a Java Servlet.
Databases: Oracle, DB2, Informix, Sybase, MySQL, SQLServer, etc The Java team has 2 standards Relational Database Structure Structured Query Language RDBMS Applies Normalization rules, among other things, reduce redundancy in data. SQL consists of Keywords & Statements. It instructs a DBMS a perform data management tasks. JDBC Java team created one API that is connected to the DBMS, formulated a SQL statement, sent the SQL statement to DBMS, then received information (data/message) from the DBMS.
The Maturing of Java JDK was released Extensions were used to Java as J2SE Java Community Programs (JCPs) developed a standard for enterprise Java APIs This enterprise edition is J2EE
Java Beans and Java Messaging Service Java promoted JMS and EJB technologies EJB consists of specifications and APIs for developing reusable server-side business components designed to run on Application servers. EJB used to encode and share business logic among clients by using.