Client-Pull refers to a technique that enables a browser/client
to request (or "pull") data from the server automatically
without the user-intervention.
The key property here is "without user-intervention."
If not for this attribute, then the term is meaningless
because it will be no different than when an user enters an
URL to request a page.
With this capability, it is possible to have a
web page that refreshes/reload itself; or even a web page that
loads another page, without the user doing anything.
Client pull can be done via cgi, by outputting this
Refresh: numOfsecond; URL=someURL
But the good news is that it can also be accomplished
by using META tag within a html page. The syntax is as
- X is the number of seconds before the reload/refresh;
- URL is the URL of the page to be loaded. Note that
according to Netscape, this should be a fully qualified
URL (complete with the site's domain name); although I've
seen it work with relative URL. Also, this doesn't
actually have to be a html page, it can be an image, or
Note that the URL field is optional.
This html code below will cause the current page
to reload itself after 10 seconds. It reload itself because
no URL is specified.
<META HTTP-EQUIV="Refresh" CONTENT="2">
This html code below will cause page2.html to be
loaded after 2 seconds. Note that there are only 2 quote
This is not a typo. It's
the way it is specified in the http specification.
In the following concrete example, client-pull is
used to create splash screens effect. Three html pages
will be loaded subsequently after 2 second.
Why would anyone want
to use this?
At the present time, client
pull has been supplanted by newer and more powerful technologies
such as "animated-gifs," Flash, or "dynamic html."
However, on its days, it has been used for:
- Web-cam applications, such as web
page that shows a real time image every some minutes.
(This is perhaps one client-pull application that is still
- Automatic slideshows
- Splash pages
- Gimmick, novelty
For further reference, consult Netscape documentation