Page 220 - DCAP408_WEB_PROGRAMMING

Web Programming

Notes  When applied to a network, the term public refers to the availability of the service,
not the data transferred. In particular, a public network offers private communication.

 How does TCP achieve reliability? The answer is complex because TCP uses a variety
of techniques to handle parts of the problem. One of the most important techniques
is retransmission.

 Application programs that communicate across a network or Internet all use a single
form of interaction. The interaction is called the client-server paradigm. A program
that passively waits for contact is called a server, and a program that actively initiates
contact with a server is called a client.

 Because no absolute definition of secure network exits, the first step an organisation
must take to achieve a secure system is to define the organisation’s security policy.
The policy does not specify how to achieve protection. Instead, it states clearly and
unambiguously the items that are to be protected.
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8.5 Summary

 Most web applications involve both client-side and server-side script. Client-side script is
often used to program the user interface for an application, for example, to change a web
page’s text dynamically, respond to user actions such as button clicks, and perform such
client-oriented tasks as input validation.

 Client-side script executes locally in the browser, which provides the user with a lively
and responsive interface.
 The web server is not only responsible for processing HTML tags but also the ASP scripts.

 The ASP engine, installed on the web server, is responsible for processing ASP scripts.
 Because the browser can only display HTML compatible text, it is the responsibility of
ASP engine to process the ASP scripts and send the results back as HTML text to the client.
In other words, the Web server sends HTML text, part of which may be the result of the
ASP scripts.

 A Web form can be made up of a single file with an .aspx extension.
 An .aspx file and a code behind file can be combined to make a Web form.
 As we’ll show in the following few days, Web forms can also contain your own custom
controls, defined similarly to .aspx pages, called user controls.
8.6 Keywords

ASP: Active Server Pages
CGI: Common Gateway Interface

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