jboss-dev-forums

[Jboss-dev-forums] [Design of Mail Services] - Re: Exception Handling

[<aco...@jb...>]

overall I think tis good but i think all exceptions should be runtime exceptions.  If you choose to catch it locally, then fine.

the state/conversational nature of the protocol doesn't always allow them to be caught at the entry point and I'm unsure that this will make the code cleaner.  

I think that we have 4 types:

1. Stream killers (so don't bother telling the user)
2. It didn't taste good/stream ok (so tell the user)
3. detached exceptions (couldn't deliever so maybe tell the user by sending him a "couldn't deliver" email preferrably with more detail than we have today!!!)
4. Panics (SQL Exception is a BAD BAD error, tell someone, bad stuff is happening, we've lost the DB, we have deadlocks, fix us!!!) -- we may want to do service unavailable rather than accept messages that won't be delivered.

-Andy

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[Jboss-dev-forums] [Design of Mail Services] - Re: Exception Handling

[mikezzz <nu...@jb...>]

I think 2 & 3 are the same (MDBs are entry points in their own special way :-).  Sending an 'couldn't deliver' email is exception handling rather than an a type of exception.  I see these as 2 orthoginal concepts.  I am happy to use RuntimeExceptions for all exceptions, but would like to have seperate base exceptions to distingush different types.

Looking closer at the protocols I see what you mean about the conversation state stuff.  However if we choose to handle the error locally then we should make sure something useful is returned to the caller.  Either return a valid object or throw an exception.  We shouldn't swallow the exception, log it and return null.  There are few cases where this happens and the protocol gets into an unknown state, throws a null pointer exception and falls over in a heap.  Also people tend to forget to check for nulls (I know I do).

Cleanliness will hopefully be a result of a consistent approach.

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[Jboss-dev-forums] [Design of Mail Services] - Re: Exception Handling

[<aco...@jb...>]

Base classes are good.

2/3 to me are different to me, mentally.  Meaning if you gave me bad stuff, I tell you to give me good stuff (authentication as an example).  Meaning if its a "other side is busted" its one thing and if I have no conversation with the user anymore, I have to do more work for the error message (create status and stick it in his mailbox potentially).

-Andy

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