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Ø The use of programming languages beyond HTML extend the
capabilities of the Web. They are used to write software, process Web forms,
fetch and display data, and perform all kinds of advanced functions. It is
difficult to talk about these languages without getting into too much technical
jargon, but here is an attempt. What follows is a brief guide to some of the
more common languages in use on the Web today.
Ø CGI (Common Gateway Interface) refers to a
specification by which programs can communicate with a Web server. A CGI
program, or script, is any program designed to process data that conforms to
the CGI specification. The program can be written in any programming language,
including C, Perl, and Visual Basic Script (VBScript). In the early days of the
Web, CGI scripts were commonly used to process a form on a Web page. Perl is
popular with Google, and is also the language of the Movable
Type blog platform.
Ø Active Server Pages (ASP): Developed by Microsoft, ASP
is a programming
environment
that processes scripts on a Web server. The programming language
VBScript
is often used for the scripting. Lightweight programs can be written with
this
language. Active Server Pages end in the file extension .asp. For an example,
check
out Databases and Indexes at the University at Albany
Libraries.
Ø .NET framework: Also developed by Microsoft,
this development framework is a more powerful one than ASP for writing
applications for the Web. Programming languages include C+ and VB.Net. ASP.Net
is a related environment, producing pages with the file extensions .aspx. The Microsoft
site is a good example of a site created with the .NET framework.
Ø PHP: This is another server-based language. It is frequently the
language used to write open source (e.g., nonprofit, community-created)
programs found on the Web, including MediaWiki (the
software that runs the Wikipedia), and the popular blog software WordPress.
While PHP functionality can be installed on Windows servers, it is native to
the Linux server environment and commonly used there.
Ø Java/Java Applets: Java is a programming
language similar to C++. Developed by Sun Microsystems, the aim of Java is to
create programs that will be platform independent. The Java motto is,
"Write once, run anywhere." A perfect Java program should work
equally well on a Windows, Apple, Unix, or Linux server, and so on, without any
additional programming. This goal has yet to be realized. Java can be used to
write applications for both Web and non-Web use.
Ø Web-based Java applications are usually in the form of Java
servlets. These are small Java programs fetched from within a Web page that
can be downloaded from a server and run on a Java-compatible Web browser. A Web
page that links to a Java servlet has the file extension .jsp.
Ø JavaScript is a very popular programming language
created by Netscape Communications. Small programs written in this language are
embedded within a
Web
page, or fetched externally from within the page, to enhance the page's functionality.
Examples of JavaScript include drop-down menus, image displays, and mouse-over
interactions. The drop-down menus on the site of the UCLA Library shown below
are a good example: when you hover your mouse over the menu item, a set of
sub-menus opens up below.
Ø XML: XML (eXtensible Markup Language) is a mark-up language that
enables Web designers to create customized tags to provide functionality not
available with HTMLalone. XML is a language of data structure and exchange, and
allows developers to separate form from content. With XML, the same content can
be formatted for multiple applications. In May 1999, the W3 Consortium
announced that HTML 4.0 has been recast as an XML application called XHTML.
Ø AJAX stands for Asynchronous JavaScript and XML. This langauge is used
to create interactive Web applications. Its premise is that it sends data to
the browser behind the scenes, so that when it is time to view the information,
it is already "there." Google Maps is a
well-known example of AJAX. A different kind of example can be found with SurfWax
LookAhead, an RSS search tool that retrieves feeds as you type your search.
Ø SQL (Structured Query Language): This
is a language that focuses on extracting data from databases. Programmers write
statements called queries that retrieve data from the tables in the database.
Some Web sites are created extensively or entirely from data stored in database
tables. You can often tell that a SQL query has produced data on a page by the
presence of a question mark (?) and a record number in the URL, as the example
below illustrates.
Ø Mashups
Ø Programs on the Web can be flexible. Sometimes they are combined
with each other to form ehanced presentations. These are known as mashups.
Ø A mashup is a Web application or Web page that combines data from
two or more external sources. Mashups give you access in one place to
information available in multiple places.
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