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.
