User`s guide

476 VEE User’s Guide
13 Platform Specifics and Web Monitoring Chapter
• The device under test (DUT), or sensor, or instrument sends
information to the server application through the network
I/O layer. The network I/O layer includes the interface and
backplane (GPIB, RS232, VXI, MXI, USB, LAN, PC
Plug- in), and the I/O programming layer such as drivers,
VISA, or SICL.
• The server application is the VEE program that generates
the measurement data.
• 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, can request information generated
by the server application.
When the Universal Resource Locator (URL) below is typed into
Internet Explorer, it requests information from an Agilent
server:
http://www.agilent.com/find/vee
• http describes the type of resource being accessed to transfer
the information.
• 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 Jscript.