Referencing an Identity attribute within web service after rule

We are trying to automate a process in which users request access to a system via Service Now, which Identity Now picks up and creates an account on an identity cube from this data. Once this SN request account has been created on the identity, it will then go off and create the subsequent account the user has requested.

The hurdle I am facing is that I need a way of referencing a particular identities attributes in the after rule, so that I can take a UID and use it to call an API to specify the task as closed completed, which will then remove the SN account from the identity cube.

Is there an easy way to do this? I have it working via an api call back into Sailpoint IDN which picks up the attributes from there, but I wondered if there was an easier and less resource intensive way of doing this?

It would be nice to have some Java docs for the libraries Sailpoint offers as well, so that we can fully understand what we are working with.

Kind regards