See the Javadocs in <EPM_ORACLE_HOME>/common/docs/ReportingAnalysis/SDK/javadoc.
This class provides static getInstance() methods that enable your program to obtain the initial Session interface it requires to do useful work in EPM Workspace. Variations of the getInstance() methods are available that enable you to specify combinations of account, password, hostname, and TCP port number that are required for logging in to EPM Workspace.