Matt,
What jar do I need?
That calls is part of
J2EE. It is in jar that comes with your application server (
JBoss, WebSphere, Weblogic, etc) and typically called J2EE.
But more importantly, how can I figure this out on my own more easily?
When using example code, they usually provide some build instructions that include this.
Sometimes you can get a clue from the package name. For example "javax.ejb.Stateless" begins with "javax". Packages that begin with "java" and "javax" (java extension) tend to be part of the specifications and located in the Java or J2EE jars.