Zend_OpenId consists of two sub-packages. The first one
is Zend_OpenId_Consumer for developing OpenID-enabled sites,
and the second is Zend_OpenId_Provider for developing OpenID
servers. They are completely independent of each other and may be used
separately.
The only common code used by these sub-packages are the OpenID Simple
Registration Extension implemented by
Zend_OpenId_Extension_Sreg class and a set of utility
functions implemented by the Zend_OpenId class.
Note
Zend_OpenId takes advantage of the GMP extension, where available. Consider
enabling the GMP extension for enhanced performance when using
Zend_OpenId.