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Web TechnologiesWeb ClientWeb Servers

Advisor: Rung-Hung Gau

Speaker: Tsai-Fang Yeh

Date: Mar. 14, 2007

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Outline

Web Clients

Basic Browser Functions-Mozilla

URLs

User-Controllable Features

Web Servers

Server Configuration

Tomcat

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Web Clients

A web client is software that accesses a webserver by sending an HTTP request message

and processing the resulting HTTP response.

In general, any web client that is designed todirectly support user access to web servers

is known as a user agent

Web browsers running on desktop or laptop

computers are the most common form

of web client software.

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Mozilla

A primary reason for choosing to use

Mozilla as a concrete browser example is

that is runs on Linux, Windows, and

Macintosh systems

Also, the fact that it is open source means

that if youre curious about details of how

a feature operates, you have access

to the source code itself.

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Title bar

Menu bar

Navigationtoolbar

Client area

Status bar

online insecure

location bar

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URLs

http://www.example.org:56789/a/b/c.txt?t=win&s=chess#para5

authority query

port number fragment

path

authority: domain name or IP address

path: is in fact concatenated by the server with a base file path in order

to form an actual file path on the servers system

query: was intended to pass search terms to a web server

fragment: are used by browsers to scroll HTML documents

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User-Controllable Features

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Web Servers

The primary feature of every web server is to accept HTTPrequests from web clients and return an appropriate resource inthe HTTP response

NCSAs httpdweb server was starting point for severdevelopment . httpdwas used on a large fraction of the early

web servers, but the NCSA discontinued development of theserver in the mid-1990s.

When this happened, several individuals who were runninghttpd at their sites joined forces and began developing theirown updates to the open-source httpd software.

Their updates were called patches, and this led to

calling their work a patchy server, which soon

became known as the Apache sever

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Web Servers

Microsofts Internet Information Server (IIS) providesessentially all of the features found in Apache, although IIShave the drawback ofrunning only on Windows systems, whileApache runs on Windows, Linux, and Macintosh systems.

Both servers can be configured to run a variety of types of

programs (VBScript, Perl, PHP, Java) When running a Java program, both Apache and IIS servers

are usually configured to run the program by using separatesoftware called servlet container.

The servlet containerprovides the Java Virtual Machine

that runs the Java program, and also providescommunication between the servlet

and the Apache or IIS web server.

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Server Configuration

Broadly speaking, server configuration can be broken into

two areas:

External communication

Coyote, which provides the HTTP/1.1 communication Internal processing

Catalina, which is the actual servlet container

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Tomcat

Tomcat is a popular, free, and open-source servletcontainer developed and maintained by the Apachesoftware Foundation.

In addition to running as a servlet container called

on by web servers, Tomcat can also be run as astandalone web serverthat communicates directlywith web clients.

The standalone Tomcat server can serve

documents stored in the server machinesfile system and run programs written

in non-Java languages.

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