Basic terminologies in Java and Web Development

JDK and JRE

What is this PATH variable?

Servers and Containers

Eclipse

Creating a web project using Eclipse – JSP

Java is the language – Library + Platform ◦ Java Card ◦ Micro Edition ◦ Standard Edition ◦ Enterprise Edition

JDK is the library ◦ The set of classes & tools (javac, java)

JRE is the platform ◦ VM that executes Java bytecode. ◦ How does the JVM know where the classes are?

Environment variables – Named values that affect the way running processes behave. ◦ Provides a standard way for accessing commonly used

processes. ◦ Eg: Temp files, Java

Where could we see the list of all ENV vars?

CRUD on ENV variables.

PATH – Specifies a set of directories where executable programs are located. ◦ Order of search – Current working directory PATH

variable (left to right) ◦ Sample – Batch script

%CLASSPATH%

Servers serve the requests from other programs.

Depending on the computing service ◦ Database server

◦ File server

◦ Mail server

◦ Web server!

◦ Application server

Web server – Deliver webpages on request from clients. Eg: Apache, IIS, Nginx

General usage : A web browser / web crawler initiates communication by making request to a specific resource, server responds with content of that resource (HTML Document)

Features : ◦ Virtual Hosting ◦ Bandwidth Throttling – fair share ◦ Server side scripting

Currently nginx is in the second position.

Modularization!

An interface between the component and the low-level-platform specific functionality.

Eg: Web Container, EJB container

Web Container (Servlet container) Web servers ◦ Interacts with the servlets

Roles of Web Container ◦ Lifecycle of servlets

◦ Mapping a URL to a servlet

◦ Access rights to an URL

Web server (with a web container)

Difference between apache and apache tomcat. ◦ Apache is C

◦ Tomcat is Java

Tomcat is configurable – server.xml

Three Components ◦ Catalina – servlet container

◦ Coyote – HTTP Connector Component

◦ Jasper – JSP Engine (converts JSP files to servlets for Catalina)

Check Tomcat server startup.

Latest version in Tomcat 7.0.26

Web Servers + Java EE concepts

Security, Data Services, Transaction Support, Persistence Support, Load Balancing etc.

Eg: WebLogic Oracle, IBM WebShere

Check JBoss AS

Exercise : Quiz website

Time : 15 mins

Completion : Not mandatory