Some back-end systems can be accessed using standard technologies such as J2EE technologies(Datasources for RDBMS or J2C adapter) or web services. if portlet needs to inter operate with one of these back-end systems and do not need any sophisticated principal mapping mechanism, it is recommended that you use these technologies
For communication with other back-end systems that require proprietary or non-J2EE protocols WPS offers credential vautl as portlet service.
Portal to back-end SSO
There are two different options for SSO between portal to back end system.