Tag: design

Interfaces with EJB3

Starting last October, we went through a process of upgrading the main application at Wotif to be running under Java EE 5 (not just Java SE 5). The biggest part of this was upgrading from EJB 2 to EJB 3.

One of the things I noticed was that EJB3 gives you a lot of choices for how to implement and configure EJBs and their associated interfaces. There’s a lot of “standards” on how to do it, many of them conflicting, but very little explanation of why. This is the set of standards I came up with (and was largely successful in getting implemented), and why I chose them.

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JBR’s Postulate 1

From the JUnit mailing list, courtesy of J.B "JUnit Recipies" Rainsberger

JBR’s postulate 1. For every testable design that requires exposing elements “just for testing”, there exists an equivalent testable design that does not require exposing elements “just for testing”.

Peering into the crystal ball: BDUF vs emergent design

There’s always a lot of debate in the various agile groups about what BDUF is, why you should avoid it, when you should avoid it, and why is it bad (or good) for you. I just thought I’d outline my own opinions here.

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It’s a bird, it’s a plane… it’s a super call?

Martin Fowler wrote about the Call Super smell. This occurs when you are allowed to override a method in a parent class, but you must (as opposed to can) call the parent implementation in your method.

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Testing pattern: don’t test too much at once

This has been said before, I know, but it’s worth re-iterating: a test should test one thing, and one thing only.

First, some scope definition. Using Kent Beck’s terminology, I’m talking about developer tests, not acceptance tests. Also, by one thing, I mean that there should be only one thing that breaks the test (which is very different from saying any failure should only break one test…). In addition, the one thing that breaks should provide diagnostic information – a test failure shouldn’t leave you scratching your head to determine the immediate cause

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Interfaces are interesting…

Cedric’s got an interesting post on obtaining extensibility via interfaces As usual, he makes a lot of very good points, and (again, as usual when I link to Cedric’s posts), there are a couple that I think could be elaborated on.
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