I assume you mean Integration Server 4.6. “webMethods” is the company that makes several products, one of which is Integration Server.
DB aliases are not intended to be used within Java services. They are for use by the webMethods-supplied DB (WmDB) services.
What are you trying to accomplish? Maybe someone can suggest an approach. If the solution simply needs to read or write DB data, then Java services are most likely not needed.
#Integration-Server-and-ESB#webMethods#Flow-and-Java-services