As you can see it supports caching of the data retrieved from the web service. The filter defined by the class admin has a description field that can be changed to a human readable text that is displayed to the student if the students status doesn't comply with the filter. The student will see a message in dotlrn that access is denied but also will receive an email.
If the web service is not available the system admin will receive a notification depending on the email specified for the service.
Since Javascript is not permitted to make cross site requests the registry service in dotlrn is serving as a proxy. Therefore it is also possible to cache data retrieved from the web service.
