JAVA 外文文献+翻译
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Java and the Internet
If Java is, in fact， yet another computer programming language， you may question
why it is so important and why it is being promoted as a revolutionary step in
computer programming. The answer isn’t immediately obvious if you're coming from
a traditional programming perspective. Although Java is very useful for solving
traditional stand-alone programming problems， it is also important because it will
solve programming problems on the World Wide Web。
1. Client-side programming
The Web’s initial server-browser design provided for interactive content， but the
interactivity was completely provided by the server. The server produced static
pages for the client browser, which would simply interpret and display them。 Basic
HTML contains simple mechanisms for data gathering ： text-entry boxes ， check
boxes, radio boxes， lists and drop-down lists, as well as a button that can only be
programmed to reset the data on the form or “submit” the data on the form back
to the server. This submission passes through the Common Gateway Interface （CGI)
provided on all Web servers。 The text within the submission tells CGI what to do with
it。 The most common action is to run a program located on the server in a directory
that’s typically called “cgi-bin.” （If you watch the address window at the top of
your browser when you push a button on a Web page, you can sometimes see
“cgi-bin” within all the gobbledygook there。) These programs can be written in most
languages. Perl is a common choice because it is designed for text manipulation
and is interpreted， so it can be installed on any server regardless of processor or
operating system.
Many powerful Web sites today are built strictly on CGI, and you can in fact do
nearly anything with it. However, Web sites built on CGI programs can rapidly
become overly complicated to maintain, and there is also the problem of response
time。 The response of a CGI program depends on how much data must be sent， as well
as the load on both the server and the Internet。 (On top of this, starting a CGI program
tends to be slow.) The initial designers of the Web did not foresee how rapidly
this bandwidth would be exhausted for the kinds of applications people developed.
For example, any sort of dynamic graphing is nearly impossible to perform with
consistency because a GIF file must be created and moved from the server to the
client for each version of the graph。 And you've no doubt had direct experience with
something as simple as validating the data on an input form. You press the submit
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