cwash into software

In Part 1, we covered the basic concept of a transaction, what the ACID properties are and how they specify transactional behavior, and why you might use transactions. This time, we’ll talk more specifically about what it’s like to use a transaction, and how the contracts it provides allow us to write data in a reliable fashion.

Programming With Transactional Systems

Commit and Rollback

Transactions either commit or rollback. Until a transaction is committed, it is assumed none of the work it has done is saved. Once a commit signal is issued by the application (either through an API call, or by a container), this work is actually performed by the transaction processing engine that’s being used. If for some reason the commit fails due to an error scenario, or some other runtime exception occurs, we assume that the integrity of the transaction has been compromised and the transaction rolls back, removing any work done up to that point. When a rollback occurs, the transaction must be resubmitted. (continue reading…)

The following scenario plays out a lot when I pair up with people, so I thought I’d distill it down and write it up for future reference. I think teaching lessons through scenarios could make for an interesting series of articles, and I’m sure others have equally interesting experiences to share.

I’ve tried to condense this down to just the steps vital to understanding the underlying problem (though this is certainly not the only way to get there) and introduce some terminology (providing links, even if deferring to google) along the way. I hope these help out aspiring or new developers.

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I recently read Scott Leberknight‘s “Can Java Be Saved?” with interest and started typing up a response.  As Scott’s article was a bit lengthy, so became the comments I had in response.  In excess of 1000 characters, which JRoller told me was spam when I finally tried to post it.  I’m still never surprised to see that happen to my writing.  Anyway, I’m probably just an oaf, but I didn’t see Scott’s e-mail listed anywhere on his site (probably another spam-deterrent choice) so I thought since I spent more than a few minutes on it, it’d be appropriate enough to post here and link it.  Sorry but I don’t have the energy to evolve this into a more formal post, perhaps I will at a later date.

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