A: 

No better place to start than reading the spec (there's a separate spec document for script engine implementers): JSR 223

Henry
Yes, I'm reading it already, but it's a bit too complex. I would appreciate something easier.
ivan_ivanovich_ivanoff
A: 

Sorry, not really a direct answer: but rather than trying to use the javax.script package, try to implement first your language. Javacc or ANTLR are a good start.

Pierre
1) Wanted only to try the API out. 2) Have already a little own language ;)
ivan_ivanovich_ivanoff
+2  A: 

What about the scripting.dev.java.net project, it includes many Script Engines (and their sources).

Pascal Thivent
Good idea! I'll look at it. Thanks!
ivan_ivanovich_ivanoff
A: 

Have a look at the Java Scripting Programmer's Guide.

John Smithers
That's more the usage part. *"We will not cover implementation of JSR-223 compliant script engines in detail"*
ivan_ivanovich_ivanoff
I see. You should mention that you want the details. "Just something to start" sounds different. ;)
John Smithers