448 Chapter 12
Platform Specifics and Web Monitoring
Web-enablement Technologies
n The server application is the VEE program that generates the
measurement data.
n The HTTP (HyperText Transfer Protocol) sends the information to the
client browser.
HTTP is one protocol in the TCP/IP communications protocol used by the
Web. (TCP/IP stands for Transmission Control Protocol/Internet Protocol.)
Lower levels of the TCP/IP protocols include transport, network, and
physical layers of communication. By definition, every TCP/IP application
is a client/server application. For example, the Client Browser (such as
Internet Explorer or Netscape Navigator) can request information generated
by the server application.
The Universal Resource Locator (URL) below typed in Internet Explorer
requests information from an Agilent server:
http://www.agilent.com/find/vee
n http describes the type of resource being accessed to transfer the
information.
n
www.agilent.com/find/vee is the URL for the resource. The
hypertext format used by HTTP is a scripting format called HyperText
Markup Language (HTML). HTML is a way to link documents together,
and originally it was the only language programmers could use to create
Web pages. Originally just for text, HTML now incorporates sound,
video, images, interactive screens, ActiveX controls and Java applets.
Once a request is made by the browser for the server information, it will not
automatically update, unless the browser is designed to do so. Also, no
interaction is allowed by the browser unless it is designed into the browser
page. The easiest way to do this is with a scripting language, such as
VBScript, JavaScript, and JBscript.
The scripting language is an interpreted language supported by the browser.
The scripting language can extend the limitations of HTML to provide a
more interactive Web page. Because they are interpreted, scripting
languages must be embedded into the Web page and supported by the
browser. They are not independent programs. This is graphically illustrated
in Figure 12-5.
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