iTP Secure WebServer System Administrator's Guide (Version 7.0)

Administering Session Identifiers for Anonymous

Sessions

iTP Secure WebServer System Administrator’s Guide—523346-012

11-10

Advanced Configuration Options

As shown in Figure 11-3, proxies act as intermediaries between a group of Web clients

and Web servers.

When a Web client issues a request in the form of a URL, the proxy first checks its

cache to see if it already has the resource. If so, the proxy returns the resource to the

Web client, sometimes without contacting the Web server at all. If the proxy does not

have the requested resource, it forwards the request to the specified Web server.

The use of proxies prevents an accurate measure of the number of times a Web page

is accessed because there is no way to know how often a proxy short-circuits a

request by returning a page from its own cache. Using tickets can reduce the problem

considerably because each request can have a unique ticket embedded in it. So even

though many users might request the same Web page, the presence of a unique ticket

will make it appear to the proxy as though each request is unique. For example, user

X’s request might be

http://www.acme.com/@@4RTgh67j8S23c5d3/info.html

whereas user Y’s request is

http://www.acme.com/@@H9bF3f0Df36Gpp3Cd/info.html

The proxy, therefore, will successfully find a page in its cache only if the same user

requests the same page a second time. Note, however, that this method works only if

the ticket is embedded in the URL. By default, the content server does not insert tickets

in URLs if cookies are enabled and the Web client supports cookies.

Figure 11-3. Proxies

Web Server

Web ServerWeb Server

Proxy

Server

Cached

Requests

and Replies

Web Client

VST018.vsd