HP WebQoS Peak for HP-UX Concepts and Operation Guide

52 Chapter5
HP WebQoS Peak for the Apache Web Server
Integrating HP WebQoS with the Apache Web Server
Responding to Rejected Sessions If conditions on the web server do
not allow servicing new requests, sessions can be redirected or rejected.
You turn on redirection indirectly by setting the redirection URL with
the HPACRedirectURL directive. For example, to redirect rejected
sessions, use the following directive in your configuration file, filling in
the appropriate URL:
HPACRedirectURL [http://] host [: port ]
NOTE A request can be redirected only to a mirror site.
A redirected session can be bounced back to the original server. You can
control how many times a session is redirected with the
HPACRedirectTTL directive (TTL stands for time-to-live). The default for
this directive is “0.” For example, to set the number of times a session is
redirected to 1, use the following directive in your configuration file:
HPACRedirectTTL 1
The number set by this directive is the number of redirections a session
has been subjected to, beyond the first one. In other words, 0 means the
session has been redirected once, 1 means the session has been
redirected twice, etc. This number should not exceed 2, to avoid wasting
the resources of the server(s) involved. (The default is probably
appropriate for most sites.)
If a session has to be rejected, the action the HP WebQoS takes depends
on the rejection policy in effect. The rejection policy can be reject,
rejectpage, or defer. It can be set using the directive
HPACRejectionPolicy. The default for this directive is “reject.” For
example, to set the rejection policy to “defer,” use the following directive
in your configuration file:
HPACRejectionPolicy defer
When the reject rejection policy is in effect, the server sends the
HTTP_SERVICE_UNAVAILABLE code and associated message to the client.
This is the easiest but least informative way to respond to a rejected
request. Users may try to reconnect right away, generating extra load on
the system.
When the rejectpage rejection policy is in effect, the server returns the
contents of a page containing a custom, more explanatory response to the