Understanding the State of an Interlink Object
PeopleSoft Business Interlink API that are run on the application server should be stateless, that is, if you want to save information from one call of the Interlink object to the next, you have to do it yourself by writing the relevant information to the database. If you use the Execute method more than once within a single PeopleCode event (that is, if you have the Execute method in some sort of loop) the state is preserved. After you leave the event, any state associated with the Interlink object is lost.
You should create only one Business Interlink object, that is, you should only use the GetInterlink function once. After that, you can load it with data, pass the data to the Interlink plug-in (using Execute) and fetch output data as many times as you need.