A specification for transferring information between a World Wide Web server and a CGI
program. ACGI program is any program designed to accept and return data that conforms to
the CGI specification. The program could be written in. any programming language,
including C, Perl, Java, or Visual Basic.
CGI programs are the most common way for Web servers to interact dynamically with
users. Many HTML pages that contain forms, for example, use a CGI program to process the
form's data once it's submitted. Another increasingly common way to provide dynamic
feedback for Web users is to include scripts or programs that run on the user's machine rather
than the Web server. These programs can be Java applets, Java scripts, or ActiveX controls.
These technologies are known collectively as client-side solutions, while the use of CGI is a
server-side solution because the processing occurs on the Web server.
One problem with CGI is that each time a CGI script is executed, a new process is started.
For busy Web sites, this can slow down the server noticeably. A more efficient solution, but
one that it is also more difficult to implement, is to use the server's API, such as ISAPI or
NSAPI. Another increasingly popular solution is to use Java servlets.
26. Write a note on Internet Information Server (IIS).
Microsoft's Web server that runs on Windows NT platforms, In fact, IIS comes bundled
with Windows NT 4.0. Because IIS is tightly integrated with the operating system, it is
relatively easy to administer. However, currently IIS is available only for the Windows NT
platform, whereas Netscape' s Web servers run on all major platforms, including Windows NT
platform, OS/2 and UNIX.
27. What are ISAPI (Internet Server API) and NSAPI (Netscape Server API)
ISAPI (Internet Server API): An API for Microsoft's IIS (Internet Information Server)
Web server. ISAPI enables programmers to develop Web-based applications that run much
faster than conventional CGI programs because they're more tightly integrated with the Web
server. In addition to IIS, several Web servers from companies other than Microsoft support
ISAPI.
NSAPI -Netscape Server API: An API for Netscape's Web servers. NSAPI enables
programmers to create Web-based applications that are more sophisticated and run much
faster than applications based on CGI scripts.
28. What is API -Application Program Interface?
A set of routines, protocols, and tools for building software applications. A good API
makes it easier to develop a program by providing all the building blocks. A programmer puts
the blocks together.
Most operating environments, such as MS- Windows, provide an API so that programmers
can write applications consistent with the operating environment. Although APIs are designed
for programmers, they are ultimately good for users because they guarantee that all programs
using a common API will have similar interfaces. This makes it easier for users to learn new
programs.
29. What are Servlets?
A small program that runs on a server, the term usually refers to a Java applet that runs
within a Web server environment. This is analogous to a Java applet that runs within a Web
browser environment.
Java servlets are becoming increasingly popular as an alternative to CGI programs. The
biggest difference between the two is that a Java applet is persistent. This means that once it is
started, it stays in memory and can fulfill multiple requests. In contrast, a CGI program
disappears once it has fulfilled a request. The persistence of Java applets makes them faster
because there's no wasted time in setting up and tearing down the process.
30. What are Applets?
A program designed to be executed from within another application. Unlike an
application, applets cannot be executed directly from the operating system. With the growing
popularity of OLE (object linking and embedding), applets are becoming more prevalent. A
well-designed applet can be invoked from many different applications.
Web browsers, who are often equipped with Java virtual machines, can interpret applets
from Web servers. Because applets are small in files size, cross-platform compatible, and
highly secure (can’t be used to access users' hard drives), they are ideal for small Internet
applications accessible from a browser.
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