Transcript Web C - bernardugalde.net

Web Concepts
Lesson 2
ITBS2203 E-Commerce for IT
What is Web?
• A global network that is based on
the Internet
ITBS2203 E-Commerce for IT
What is Web server?
• It is a computer/machine (hardware) that
hosts web sites and software that runs on
such a machine and processes requests from
Web browsers which is called web client
software.
ITBS2203 E-Commerce for IT
Functions of the Web Server
1. It must run continually and must always be
ready to respond to the requests of the client
2. It must be able to serve more than one client at
a time.
3. It stores text, images, audio, video and other
shared elements
4. The various processes have to be able to connect
to each other and exchange information
ITBS2203 E-Commerce for IT
Most Popular Web Servers
• Apache web server
– HTTP web server
• Microsoft Internet Information Services (IIS)
– Windows server
• Apache Tomcat
– Developed to support servlets and JSP scripts.
ITBS2203 E-Commerce for IT
What is Web Browser
• It is a computer program (software) that is
used for viewing web sites and web pages
whether you use a desktop computer, a laptop
or even a mobile device such as your cell
phone.
ITBS2203 E-Commerce for IT
Most Popular Web Browsers
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Chrome
Microsoft Internet Explorer
Firefox
Opera
Apple’s Safari
ITBS2203 E-Commerce for IT
What is HTTP Protocol?
• It has a set of instructions for accurate
information exchange.
ITBS2203 E-Commerce for IT
HTTP Client Methods – GET and POST
• The GET Method
– The GET method is used to retrieve web pages from the web server.
– It is a part of the request line from the client and tells the server to
pass a copy of the document back to the browser.
• The POST Method
– Data from the POST method is sent by the client as a part of the
request body.
– The server receives this data and sends it to a PHP parser along with
other variables.
• The HEAD Method
– It is used to find information about a document located on the server
not retrieve it.
– It is very similar to the GET method except no data is returned by the
server.
ITBS2203 E-Commerce for IT
Client-Side Scripting Languages or
Technologies
• Scripting Languages or Technologies include:
• HTML, DHTML, CSS, JavaScript, VB Script (Visual Basic
Script) Java applets...
• Browser plug-ins: Java, Flash, Shockwave, Quicktime,
Silverlight etc...
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Advantages
Processing done by the web browser
Fast
Minimal demands on server : files are
downloaded to client for execution
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Disadvantages
There is no database access!
Cannot depend upon client-side code
Browser dependency
Different browsers have different behaviors
Browser plug-ins man not be installed: Flash,
Java, Shockwave
ITBS2203 E-Commerce for IT