Cross-posting as advised from DeveloperWorks: https://developer.ibm.com/answers/questions/212469/can-an-application-hosted-outside-bluemix-access-s.html
I am exploring a scenario wherein I have an existing Java application hosted on-premises outside BlueMix. I want to make it horizontally scalable. As part of this change I would like to know if I can provision a BlueMix Session Cache service to store the application's session state externally. The application will continue to be hosted outside BlueMix but use BlueMix Session Cache for session state management.
It is not possible at the moment.
Although a person can setup a Liberty runtime with the right connection information copied from VCAP and runtime variables, and use it to host a web application that use session cache client, this machine is outside Bluemix and won't be trusted by the network. As a result, it won't be able to connect to the session cache within Bluemix.