[jboss-user] [EJB 3.0] - Re: SLSB basic design question

ALRubinger do-not-reply at jboss.com
Mon Aug 18 13:23:43 EDT 2008

"vanyatka" wrote : ...if I only run one single facade method, and previous old state doesn't bug me (all variables are re-initialized before used), can such "temporal" use of fields be justified?

Sure, but you've set up a maintenance "gotcha" that is pretty easy to violate and will be difficult to debug.  Also, you'll be less likely to see the inconsistencies exhibited in development, meaning it's likely that Peter's "weird stuff" will happen in Production.  So as a general rule, I'd avoid this paradigm unless you can say:

1) There's no cleaner way
2) Document the hell out of it to make sure the instance var is cleansed upon each invocation

"vanyatka" wrote : Imagine I have a chain of methods inside a SLSB.
  | a calls b, b calls c, c calls d, etc.
  | Facade method receives a parameter. I need to use that parameter down the chain of execution. Should I put that parameter in each method declaration? Ouch ... Doesn't look very appealing, don't you think

No, cluttered APIs are not pretty, though this approach *is* pretty foolproof. 

You can also look into:

1) Store that parameter in a ThreadLocal
2) Each method looks to the ThreadLocal for the value
3) Apply an interceptor to, after invocation, clear the value of the ThreadLocal (as the Thread will also be returned to a pool).


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