Modern Software Technologies Java™, J2EE™, JSP™, JDBC™ by Radoslav Tr. Ivanov

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 1. “ ” ; 2. “ ” - Scriptlets; 3. “ ” - Expressions; Example: Current time:

Java Server Pages ™ Possible creating of new “ ” 1. MyTags.tld – file of tags Example: 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 – Jakarta TomCat ™ Apache™ –

Resources