Modern Software Technologies

Modern Software Technologies

Java™, J2EE™, JSP™, JDBC™by Radoslav Tr. Ivanov - 12835

Contents

Java™ language

J2SE™ & J2EE™

Business Systems

J2EE™ Platform

J2EE™ components: JSP™ Servlets™ JDBC™ & EJB™

Web Servers for J2EE™

Resources

1. The Java™ language ”... write once, run anywhere …”

• History –1991 “Oak”- microprocessors ;• Necessity of platform

independence ;• Advantages – suitable for WEB

OOP-multi-platform, secure, simple and clear; inheritance, polymorphism, classification no need for garbage-collecting, near to “C++” ;

• Disadvantages – slow ;

A Java Program: From Birth to Execution

1. Coding -Human-readable Java code is produced by the programmer 2. Building - A Java Development Tool "build"s the Java program into

byte-code, which is saved as a ".class" file. 3. Loading - Via the web or command line, the class file is sent to the

Java Virtual Machine (VM) with an attached digital signature. The Java VM is simply an interpreter.

4. Bytecode Verification - The Java VM verifies the digital signature. 5. Isolation - When downloaded remotely, the Java VM isolates the

Java program in a restricted part of memory. The Java program is not allowed to access local Hard drives and System resources.

6. Internal Integrity - Verification checks are made to insure that the loaded Java program is well formed. Data types are verified along with other syntax structure

7. Execution - Program execution begins

Java™, J2EE™, JSP™, JDBC™

2. J2SE™ & J2EE ™

3. Business Systems• Client Server (DB) 2-tier ;• Client Application Sever Server

(DB) 3 tier ;• N-tier ;

4. The Middle Tier

Business logic

Presentation logic

J2EE Platform

5. J2EE components:• Servlets™, JSP™, EJB™, JDBC™ etc.

6. Java Servlets.• Common with CGI ;• Life cycle of Servlets -init(), service(), destroy() ;• Advantages – good for Business logic;• Disadvantages – It’s not suitable for web design;

7. Java Server Pages ™

• Advantages over ASP™, PHP™, Servlets• Life cycle – converted to Servlet;• Tags

• <%-- “JSP comments”--%>1. “<%! “Declarations” %>” ; 2. “<% “Code” %>” - Scriptlets; 3. “<%= ‘dynamic expression’ %>” - Expressions;

Example: <HTML>Current time: <%=new java.util.Date()%”>

</HTML>

Java Server Pages ™

• Possible creating of new “<tags>” 1. MyTags.tld – file of tags

Example: <%@ taglib=“path to MyTags.tld”%>

• Suitable for locale independence

8. EJB™ & JDBC™

Java Data Base Connectivity (API) -(driver) – implemented classes and methods for managing Data Base ( Informix, MySQL, Oracle etc.)

EJB™ – Enterprise Java Beans™Example – shopping card

9. Web Servers for J2EE™

Orion –http://www.orionserver.com

Jakarta TomCat ™ http://jakarta.apache.org/

Apache™ – http://apache.org/

Resourceshttp://java.sun.com

http://java.sun.com/docs

http://www.javaworld.com

http://www.sun.com

http://java.sun.com/j2ee

http://java.sun.com/j2ee/tutorial

http://developer.java.sun.com/

http://www.javacoffeebreak.com/tutorials/

Documents

Modern Software Technologies