MetaphoricQuestioning

As regular readers of my work may know, I'm very suspicious of using metaphors of other professions to reason about software development. In particular, I believe the engineering metaphor has done our profession damage - in that it has encouraged the notion of separating design from construction.

As I was hanging around our London office, this issue came up in the context of Lean Manufacturing, a metaphor that's used quite often in agile circles - particularly by the Poppendiecks. If I don't like metaphoric reasoning from civil engineering, do I like it more from lean manufacturing?

16 December 2004

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Dominica

We recently took our annual dive vacation. Whenever we do this we face a dilemma - do we go to Saba which we love so much, or do we try something new? Our answer to this was to go to Saba and somewhere new, which led to a longer vacation that made up for the long trip down from the frozen North East. Our new place was Dominica.

6 December 2004

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OOPSLA2004

I've been attending OOPSLA for over a decade. It's become the place where I catch up with lots of friends and find out what they've been doing lately, and try to get a sense of where the OO community is going.

3 November 2004

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ScopeLimbering

One of the basic tenets of agile development is that requirements changes aren't just expected, they are welcomed. This poses a particular challenge when an external company, like ThoughtWorks, is doing work for client. Many clients want a FixedPrice arrangement, which is really fixing scope because they see the FixedScopeMirage. But a fixed scope contract is totally at odds with agile development, so what is a company like us to do?

27 October 2004

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StaticSubstitution

As I listen to our development teams talk about their work, one common theme is their dislike of things held in statics. Typically we see common services or components held in static variables with static initializers. One of the big problems with statics (in most languages) is you can't use polymorphism to substitute one implementation with another. This bits us a lot because we are great fans of testing - and to test well it's important to be able to replace services with a Service Stub.

20 October 2004

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FixedScopeMirage

Many companies like the idea of writing a contract that fixes scope and price because they think it lowers their risk. The mirage says that their financial obligation is fixed at the price of the deal. If they don't get satisfactory software, then it won't cost them.

30 September 2004

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StandardStoryPoints

I've heard a couple of questions recently about coming up with a standard story point mechanism for multiple teams using extreme programming's planning approach. The hope is have several teams all using equivalent story points, so that three story points of effort on one team is the same as on another.

I think trying to come up with this at best of limited value, and at worst dangerous.

6 September 2004

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IsFixingAnUnknownBugRefactoring

Here's an interesting conundrum posed by Przemyslaw Pokrywka. One of the refactorings in the book is Introduce Null Object - a very useful refactoring (also discussed in Josh's new book.) Przemyslaw's point is that this refactoring can alter behavior. If you have a method return a null, and you invoke a method on that null you'll get a null pointer exception. If you use a Null Object you'll get some default behavior.

3 September 2004

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Fail Fast

Jim Shore

If software's going to go south, Jim explains in this column why it should collapse as fast as possible.

September 2004

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JunitNewInstance

I often get questions that surround one of the design choices in the JUnit testing framework - the decision to make a new object for each test method run. Enough to warrant a quick bliki entry. (However I feel almost compelled to point out that my writing about JUnit does not mean that that I don't think that other forms of testing are important. There are lots of useful testing activities, and although JUnit and its cousins are valuable for many of them it isn't the solution for everything. For more blogging on testing I suggest you look at the blogs of Brett Pettichord, Brian Marick, and James Bach. You should also not assume that my writing about xUnit testing implies suggests the unimportance of refactoring, use cases, or flossing.)

24 August 2004

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CourtesyImplementation

When you a write a class, you mostly strive to ensure that the features of that class make sense for that class. But there are occasions when it makes sense to add a feature to allow a class to conform to a richer interface that it naturally should.

12 August 2004

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FaultyTechniqueDichotomy

My main inspiration in life is trying to capture and improve the way in which we do software development. So I spend a lot of time talking to people about various techniques they've used, which ones work well and which ones suck.

As I do this, I often hear about faulty techniques: "FIT wasn't worth the effort", "never put any logic in stored procedures", "test driven design led to a chaotic mess". The problem with any report of a faulty technique is to figure out if the technique itself is faulty, or whether the application of the technique was faulty.

5 August 2004

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BelkinKvmLinux

(Problems with mouse, Belkin KVM switch and Linux)

4 August 2004

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AssertionFreeTesting

Here's a story from a friend of a friend. I'm sure it must be true, at least somewhere.

3 August 2004

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InstallingDebian

In recent months I've gone on a major binge of installing Debian Linux. In the last few months have seen a lot of new environments appear in my setup. I've acquired a new desktop machine which I installed Windows XP on, a Powerbook laptop with MacOS X, and a new work laptop with windows XP. All of these involve various amounts of work, even my work laptop, which came with a ThoughtWorks configured Windows XP already on it, needed work to install the various applications that I use in my work.

1 August 2004

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StranglerApplication

When Cindy and I went to Australia, we spent some time in the rain forests on the Queensland coast. One of the natural wonders of this area are the huge strangler vines. They seed in the upper branches of a fig tree and gradually work their way down the tree until they root in the soil. Over many years they grow into fantastic and beautiful shapes, meanwhile strangling and killing the tree that was their host.

29 June 2004

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UmlSketchingTools

I draw a lot of UML diagrams, but I don't use CASE tools. The reason is that I'm interested in UmlAsSketch, not in all the repository stuff. So far my regular choice has been Visio. Although Visio comes with UML templates I don't use the built in ones - I prefer those of Pavel Hruby.

16 June 2004

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DiffDebugging

I was working on some example code for one of my writing projects recently when I ran into a failing test. "Ouch", I thought, "those tests were passing last week - what happened?" Rather than trying to find the bug in the code in front of me, I used what I think I'd like to call diff debugging.

1 June 2004

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DatabaseStyles

When I talk about databases and how they relate to applications, I've found it useful to distinguish between two styles of database: ApplicationDatabase and IntegrationDatabase. The difference between the two lies in whether the database is controlled and encapsulated within a single ApplicationBoundary.

24 May 2004

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Quantity

Handling dimensioned numbers such as: 12 ft and $9.99

10 May 2004

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XpVelocity

I've seen this confused in a couple of places now, so I feel the urge to re-state what the meaning of the term velocity is in Extreme Programming.

10 May 2004

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Is Design Dead?

For many that come briefly into contact with Extreme Programming, it seems that XP calls for the death of software design. Not just is much design activity ridiculed as "Big Up Front Design", but such design techniques as the UML, flexible frameworks, and even patterns are de-emphasized or downright ignored. In fact XP involves a lot of design, but does it in a different way than established software processes. XP has rejuvenated the notion of evolutionary design with practices that allow evolution to become a viable design strategy. It also provides new challenges and skills as designers need to learn how to do a simple design, how to use refactoring to keep a design clean, and how to use patterns in an evolutionary style.

May 2004

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AgileCertification

Certification programs are common in the software industry, yet most capable developers I know have very little regard for them. The general view is that certification has little correlation with competence. This is compounded in the agile community with certification's association with the CMM - which is historically anything but agile.

30 April 2004

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IsAgileForAll

I've often heard the claim that agile methods can only be used by the better developers and that average or below average developers should avoid agile methods. When I get asked this, I have to answer that I don't know the answer - and that this ignorance is natural with any new technique.

4 April 2004

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SpecificationByExample

I was attending a workshop at XP/Agile Universe in 2002 when the phrase 'Specification By Example' struck me as a way to describe one of roles of testing in XP.

18 March 2004

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SoftwareDevelopmentAttitude

Many debates in software development are underpinned by whether the speaker has a DirectingAttitude or an EnablingAttitude. These different attitudes affect choices over languages, designs, tools, processes, and lots more.

8 March 2004

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DataModels

One of my early favorite books was Tsichritzis and Lochovsky's book on Data Models. The book discussed different models for thinking about data, in particular the three models most discussed at the time: RelationalDataModel, HierarchicDataModel and NetworkDataModel.

12 February 2004

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ModelDrivenArchitecture

Some people think that Model Driven Architecture (MDA) will be biggest shift in software development since the move from assembler to the first high level languages. Others think that it's nothing more than Night of the Living Case Tools. I'm in the latter camp but feel the need for more than a slick saying.

2 February 2004

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DecoratedCommand

This is a very common pattern and also very simple, it's really just the decorator pattern applied to commands. I've seen it used a lot with CommandOrientedInterfaces. You also hear this referred to as interceptors and as a form of Aspect Oriented Programming.

24 January 2004

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BuildLanguage

Bruce Eckel's recent post on ant and make triggered me to share some of my thoughts about build languages. Both ant and make specify how builds happen, they are a language for describing builds. Both are pretty widely used and have been successful. Yet both run into limitations, with larger systems it's quite common to find people generating their ant/make files from other programs.

17 January 2004

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PeopleOriented

One of the most difficult things for many people to understand about agile methods is the people orientation of agile. Those who are interested in agile processes all agree that process is a second-order effect on project success. The first value of the agile manifesto is that Individuals and Interactions are more valuable than Process and Tools.

12 January 2004

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Continuous Design

Jim Shore

The rising popularity of refactoring, tools such as JUnit, and agile methodologies such as Extreme Programming (XP) has brought a new style of design into view. Continuous design is the process of using refactoring to continuously improve a program's design. In this column Jim discusses his experiences with continuous design, in particular with design issues that seem tricky such as internationalization and transactions.

January 2004

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