Web Basics

1. WEB Basics
SAGAR PUDI | SOFTWARE DEVELOPER
CONNECT ME HERE : IN.LINKEDIN.COM/IN/SAGARPUDI

2. AGENDA
• CLIENT-SERVER ARCHITECTURE
• HTTP PROTOCOL
• THICK CLIENT
• THIN CLIENT
• WEB SERVER
• APPLICATION SERVER
• PACKAGING APPLICATIONS FOR DEPLOYMENT (JAR, WAR, EAR)
• DEPLOYMENT DESCRIPTOR (WEB.XML)
• URL

3. CLIENT-SERVER ARCHITECTURE
Fig.1.1 Client-Server Architecture

4. EXAMPLE OF CLIENT-SERVER ARCHITECTURE
Fig.1.2 Example of Client-Server Architecture

5. HTTP METHODS
• OPTIONS
• GET
• HEAD
• POST
• PUT
• DELETE
• TRACE
• CONNECT

6. HTTP STATUS CODES• 1XX –INFORMATIONAL
• 2XX –SUCCESS
• 3XX –REDIRECTION
• 4XX –CLIENT ERROR
• 5XX –SERVER ERROR

7. THICK CLIENT(FAT CLIENT)
• A THICK CLIENT IS A COMPUTER THAT DOES NOT REQUIRE A CONNECTION TO A
SERVER SYSTEM IN ORDER TO RUN (UNLIKE A THIN CLIENT), ALTHOUGH THEY CAN
BENEFIT FROM BEING CONNECTED TO A NETWORK AND A SERVER.
FIG.1.3. PERSONAL COMPUTER, A FORM OF THICK CLIENT.
• THICK CLIENTS HAVE THEIR OWN OPERATING SYSTEM AND SOFTWARE
APPLICATIONS AND CAN BE USED OFFLINE.

8. THIN CLIENT
• THIN CLIENTS ARE NOT TYPICAL COMPUTERS, BUT RATHER A TERMINAL THAT RELIES ON
ANOTHER COMPUTER SYSTEM (USUALLY A SERVER) TO SUPPLY THE OPERATING SYSTEM AND
SOFTWARE APPLICATIONS NEEDED BY THE USER.
FIG.1.4. THIN CLIENTS CONNECTED TO THEIR SERVER VIA A COMPUTER NETWORK.

9. WEB SERVER
• A WEB SERVER IS A COMPUTER SYSTEM THAT PROCESSES REQUESTS VIA HTTP,
THE BASIC NETWORK PROTOCOL USED TO DISTRIBUTE INFORMATION ON
THE WORLD WIDE WEB.
• THE TERM CAN REFER EITHER TO THE ENTIRE SYSTEM, OR SPECIFICALLY TO THE
SOFTWARE THAT ACCEPTS AND SUPERVISES THE HTTP REQUESTS.
• APACHE AND IIS ARE THE MOST USED WEB SERVERS ON THE INTERNET.

10. APPLICATION SERVER
• AN APPLICATION SERVER CAN BE EITHER A SOFTWARE FRAMEWORK THAT PROVIDES
A GENERALIZED APPROACH TO CREATING AN APPLICATION-SERVER
IMPLEMENTATION, REGARD TO WHAT THE APPLICATION FUNCTIONS ARE, OR THE
SERVER PORTION OF A SPECIFIC IMPLEMENTATION INSTANCE.
• IN EITHER CASE, THE SERVER'S FUNCTION IS DEDICATED TO THE EFFICIENT
EXECUTION OF PROCEDURES (PROGRAMS, ROUTINES, SCRIPTS) FOR SUPPORTING ITS
APPLIED APPLICATIONS.

11. PACKAGING JAVA APPLICATIONS
• JAR –JAVA ARCHIVE
• JAR (JAVA ARCHIVE) IS A PACKAGE FILE FORMAT TYPICALLY USED TO
AGGREGATE MANY JAVA CLASS FILES AND ASSOCIATED METADATA AND
RESOURCES (TEXT, IMAGES, ETC.) INTO ONE FILE TO DISTRIBUTE APPLICATION
SOFTWARE OR LIBRARIES ON THE JAVA PLATFORM.

12. PACKAGING JAVA WEB APPLICATIONS
• WAR –WEB APPLICATION ARCHIVE

13. PACKAGING JAVA ENTERPRISE APPLICATIONS
• EAR –ENTERPRISE APPLICATION ARCHIVE

14. DEPLOYMENT DESCRIPTOR
• A DEPLOYMENT DESCRIPTOR IS AN XML DOCUMENT WITH AN .XML EXTENSION
THAT DESCRIBES THE DEPLOYMENT SETTINGS OF AN APPLICATION, A MODULE,
OR A COMPONENT. BECAUSE DEPLOYMENT DESCRIPTOR INFORMATION IS
DECLARATIVE, IT CAN BE CHANGED WITHOUT THE NEED TO MODIFY THE
SOURCE CODE.
• AT RUNTIME, THE JAVA EE SERVER READS THE DEPLOYMENT DESCRIPTOR AND
ACTS UPON THE APPLICATION, MODULE, OR COMPONENT ACCORDINGLY.
( E.G. : WEB.XML, APPLICATION.XML )

15. WEB.XML
• A WEB APPLICATION'S DEPLOYMENT DESCRIPTOR DESCRIBES THE CLASSES,
RESOURCES AND CONFIGURATION OF THE APPLICATION AND HOW THE WEB
SERVER USES THEM TO SERVE WEB REQUESTS.
• WHEN THE WEB SERVER RECEIVES A REQUEST FOR THE APPLICATION, IT USES
THE DEPLOYMENT DESCRIPTOR TO MAP THE URL OF THE REQUEST TO THE
CODE THAT OUGHT TO HANDLE THE REQUEST.
• WEB.XML IS PART OF THE SERVLET STANDARD FOR WEB APPLICATIONS.
1. CONFIGURING AND MAPPING A SERVLET
2. SERVLET INIT PARAMETERS
3. SERVLET LOAD-ON-STARTUP
4. CONTEXT PARAMETERS

16. URL
• URL IS AN ACRONYM FOR UNIFORM RESOURCE LOCATOR AND IS A REFERENCE (AN
ADDRESS) TO A RESOURCE ON THE INTERNET.
URL=PROTOCOL IDENTIFIER + RESOURCE NAME
[SCHEME://HOSTNAME:PORT/PATH?NAME=VALUE]

17. MAKE THINGS AS SIMPLE AS YOU CAN BUT NOT
SIMPLER EINSTEIN

18. THANK YOU