I introduced the factory facility of windsor (or actually castle microkernel) at the end of my previous project and I submitted some patches on it's programmatic use, and there is not so much documentation on it (well, not any on that part) so a little writeup was in order.

What is windsor? 

If you don't know what a container/IoC/DI is, and like to know concepts, check this out. If you don't know and want an example of windsor, check this out. A container is a little piece of frameworkish code that takes care of constructing your instances for you in a OO program, so you don't have to keep track of what goes where which simplifies alot.

You use it by first describing the classes you use and then asking for an instance of one. For example, you can tell it that you have a class D that uses an instance of class A and C. Class C in turn needs an instance of a class B. This is done in some init area of your code. Then in the program, you can say give me a D (resolve), and it will create A, create B and use it to create C and use these to create a D and return to you. Example classes:

publicclass A
         { }

publicclass B { }

publicclass C

{

public C(B instanceOfB) { }

}

publicclass D

{

public D(A instanceOfA, C instanceOfC)
         { }

}

Example use in test:

[Test]

              public
              void MostBasicExample()

{

   IKernel container = new DefaultKernel();

   container.AddComponent("keyForClassA", typeof(A));

   container.AddComponent("keyForClassB", typeof(B));

   container.AddComponent("keyForClassC", typeof(C));

   container.AddComponent("keyForClassD", typeof(D));

   D anAInstance = 

      container.Resolve("keyForClassD", typeof(D)) as D;

   Assert.That(anAInstance, Is.TypeOf(typeof(D)));

}

Concepts/acronymns are "inversion of control" and "dependency injection", I like to refer to it as just a container, it's imprecise and contextual instead of sacrificing simplicity to get precise, but that's who I am. It's just oo, really. There are several such pieces of container code for .NET; castle windsor, spring.net and the objectbuilder framework from ms that is used in their application blocks, etc. I personally favor the castle project implementation because of it's ease of use and simplicity.

Use your own wrapper 

I feel the default container lacks some stuff, so I wrap it and add generics, methods that omit the key (sometimes I know that I will only have one implementation of a class in a system) and that look at metadata for attributes in an assembly and auto register. I make my wrapper a singleton. I slap on a custom attribute I call "ContainerComponent" on the example classes above and the test becomes:

[Test]

                public
                void MostBasicExample()

{

   Container.Instance.AddFromAssemblyOf<A>();

   D anAInstance = Container.Instance.Resolve<D>();

   Assert.That(anAInstance, Is.TypeOf(typeof(D)));

}

(In fairness, there have been some recent commits that move toward this.)

The factory facility example 

Windsor can be extended via facilities, small pieces of code that add small pieces of functionality. The factory facility allows us to tell windsor to use a certain method (instance or static) on a class to create an instance of a class. I added some simple methods to add factories programmatically. Here are some example classes:

publicinterface IUserRepository

{

void UpdateUser();

}

publicclass UserRepositoryImplementation
         : IUserRepository

{

publicvoid UpdateUser()

   {

   }

}

publicclass UserRepositoryFactory

{

public UserRepositoryImplementation Create()

   {

returnnew UserRepositoryImplementation();

   }

}

Factory support facility programmatically 

Here is an example test using microkernel and programmatically using the factory support facility (currently in trunk):

[Test]

              public
              void FactoryResolveWithProposedFacilityPatch()

{

   IKernel kernel = new DefaultKernel();

   FactorySupportFacility facility = 

              new FactorySupportFacility();

   kernel.AddFacility("factory.support",
         facility);

              string userRepositoryKey = "userrepository";

   facility.AddFactory<IUserRepository, UserRepositoryFactory>

      (userRepositoryKey, "Create");

   IUserRepository userRepository = kernel.Resolve(

      userRepositoryKey,

              typeof(IUserRepository)) as IUserRepository;

   Assert.That(userRepository, 

      Is.TypeOf(typeof(UserRepositoryImplementation)));

}

I think that is messy, if we use a little container wrapper and say that we have don't need the key to differentiate

between implementations, it becomes:

[Test]

              public
              void FactoryResolveWithContainer_NoKey()

{

   Container.Instance

      .AddFactory<IUserRepository, UserRepositoryFactory>

      ("Create");

   IUserRepository userRepository = 

      Container.Instance.Resolve<IUserRepository>();

   Assert.That(userRepository, 

      Is.TypeOf(typeof(UserRepositoryImplementation)));

}

Fuller example

Here are some example classes for a fuller example:

              public
              class FileStorageService

   {

   }

              public
              class AnnounceService

   {

              private FileStorageService _storage;

              private IUserRepository _userRepo;

              public IUserRepository UserRepo

      {

         get { return _userRepo; }

      }

              public AnnounceService( FileStorageService fileStorage,

         IUserRepository userRepo )

      {

         _storage = fileStorage;

         _userRepo = userRepo;

      }

   }

Example:

[Test]

              public
              void FactoryResolveWithContainer_FullerExample()

{

   Container container = Container.Instance;

   container.AddFactory<IUserRepository, 

      UserRepositoryFactory>("Create");

   container.AddComponent<FileStorageService>();

   container.AddComponent<AnnounceService>();

   AnnounceService announceService = 

      container.Resolve<AnnounceService>();

   Assert.That(announceService.UserRepo, 

      Is.TypeOf(typeof(UserRepositoryImplementation)));

}

Parameters 

You can set parameters for the factory method at configuration time and at runtime. Will continue with that and post code later on, stay tuned.

At the last meeting of our monthly agile get togethers (which was really nice) we talked about a bunch of things; one being how to help teams keep using techniques that are helpful and reflect on what they do so that they may find new helpful techniques.

At my current short assignment I am helping a team with their process and their work and we have been talking about these things, so the discussion was very useful to me. The reward of task completion and (if you have a quick feedback cycle via some receiving customer standing by) delivery is huge and it can be hard to provide an alternative mechanism that rewards refactoring and design investments.

One type of tool I find useful to get a grip on group dynamics are the personality catalogs a'la DISC. There is a correlation between the personality types of such models and preferred rewards, "Drivers" are more focused on task completion and delivery, for example. However, the model notes a tendency or potential factor, it is not static - the challenge is to affect this focus in a beneficial direction, usually so that more design effort is undertaken.

There is little point in enforcing policies by means of negative reinforcement. At AgileOresund we discussed how to stimulate a feeling of professionalism / "professional pride" so that there will be more care taken in how things are accomplished than just that they are accomplished.

I feel that this can be approached via a general belief and support of the individual, and a stimulation of his/her personal goals. These goals are often in line with the goals of the organization, and create a much greater drive. A dialogue aimed at this is often neglected in companies today: Many companies I've been to lack leaders who have the ability to create a solid and effective conversation of this type. In contrast, the "actual" leaders (may be team leads or just in terms of the socially context, due to age and experience) are sometimes not interested and/or do not have time and do not prioritize this important conversation. I feel that this is a loss for everyone - the companies, the industry as a whole and the individuals.

Another perspective on this discussion is the model of developers that microsoft uses, and there has just recently been some controversy around how it was recently expressed at a blog. Microsoft uses a set of persona that represent different developers. In a recent post - an discussion of code production and tools - quality and needs were presented based on one of the persona, Mort. Mort is the least technically interested developer, that merely wants to get the job done, and the code he produces does not fit in a complex codebase that will need to be maintained over a long period of time, and so on, it is posited. There follows (and it is still active) a heated and fairly interesting discussion, where people mostly disagree with how the original poster related Mort and his view of the world to agile practices.  Regardless, using these persona as an analysis tool in this way feels clumsy to me, I don't think that it is what they were intended for. 

Yet it does send a thought to my rewards analysis: If we accept the persona model as useful, and think about the Mort persona in a typical scenario, I think that Morts in general will be aware that they are not the "alpha geeks". Morts may feel a sense of distance and lack of engagement due to this. Thus, they pursue other types of rewards and recognition, which may be task completion. If so, it seems logical that they value it over investing effort in design, and other technical aspects of the work, that do not contribute "directly" to creating the functionality in a visible way. They may feel that they cannot gain recognition for creating the best design for the tasks, but they can complete the tasks quickly.

Naturally, creating an open and positive work environment is of course necessary.

  Again, in order to counter this is (in addition to pursuing and maintaining humility and openness at all costs, as has been recommended forever) I believe in working with the individual and pushing them to create a vision for themselves, get aware of their ambitions and formulate a direction of where they want to go. Most often, that will be in line with where the organization wants to go. I believe very much in the drive and the passion that we all have, if awakened, if nourished -  all it takes is someone to believe in it.

This week was short work-wise, and went by quickly. Last week was hectic and long. Me and my colleague Truls gave a seminar on NHibernate, a little ActiveRecord and some of the new MS OR stuff. Then I spent three days with another consulting company, showing them the ins and outs of NHibernate and sprinkling just a little WCF on the last day. In so doing, I caught myself serving out some code that I have used. Normally, I don't dish out any code here, but this might be useful to some:

It's a small WCF test helper that I have used to do explorative testing of WCF and even more so for integrative smoke tests of WCF services.

There is a zip attached that contains one vs.net 2005 project with a WCF hello world and one nunit test that runs that service. That test is an integration test, it cranks up the whole WCF machinery. Most of my WCF integration tests (all, in fact) do not test any concurrency issues. They are more simple smoke tests that everything seems to work as expected. What I usually want is to test the machinery but have one instance invoked, so that I can execute some assertions on the results using that instance afterwards.

Usually, you will not implement your WCF service as a singleton (although it is one of the instancing modes), for one of several reasons - scalability for example. Using the other instancing modes means that you (by default) do not control construction of your the instance that gets to serve the requests, and thus in a test situation, we do not have a reference to the instance used by WCF. One way around this is to create a custom instance provider. The instance provider in WCF (class implementing IInstanceProvider, the default being a private class in InstanceBehavior, reflect it) is responsible for supplying new service instances. I won't talk about it here, suffice it to say that my SingletonInstanceProvider simply returns one (settable) instance each time, thus making the service a singleton. It is a service behavior that we add to the servicehost description.

Why do this? Simply so that I can implement my service using an instancing mode that I want, but still run simple smoke tests on it. It is one solution, there are doubtless many others, if you have a better one, please give me a shout.

So, the testhelper or testharness that is enclosed actually does a couple of things. I won't talk about them in detail, this is roughly it:

• Provide a simple way to create and start a service host and get a client to run tests against it.
• Provide a way for tests to share services, so that the WCF machinery does not need to be restarted.
• Get the services set up using the SingletonInstanceProvider easily
• Allow test to access host before it is started to modify/further configure
  ( this is why you see castle in there, the client (a dynamic proxy wrapper) is actually a proxy that opens the service late/JIT )

You use it like so:

IMessageOfTheDay client1 = GetClient

   .For<IMessageOfTheDay>()

   .Using(new NetTcpBinding())

   .Running(serviceInstance);

This sets up a service host for the IMessageOfTheDay service contract, using the netTcpBinding (optional, default is named pipes since it is the fastest) and running the instance supplied. See the demotest.

Comments welcome. Btw, this uses my singleton implementation, I'll make a note of that tomorrow, but it's simple.

Questions: Has anyone seen another wcf test harness like this? I usually do all my network integration testing using some thread harness with synchronization between, and did my WCF testing in a similar (not the same) way. This harness simplified things quite a bit.

BTW: Most of the code is in one file; TestHelper.cs. It's a bit unwieldly, sorry, but easier to copy - you still need the singleton.cs though. I may update later if I get time.

Again, the download is here.

I am here in Cambridge, at the SPA conference, and held a workshop on testability and encapsulation. I promised to publish my sources, so here they are! I will post presentation in the near future.

Most of the articles can be found via acm (portal.acm.org) or ieee, but I always search via google which usually leads to acm.

Abstraction, information hiding and encapsulation

Most of the good stuff here is from different OOD books. Here are some old articles I found interesting, (tiny archaeological warning), worth skimming:

    "Data abstraction and hierarchy"
        Barbara Liskov
        OOPSLA 1987
    "Encapsulation and inheritance in OO programming languages"
        Alan Snyder
        OOPSLA 1986
    "Encapsulation constructs in systems programming languages"
        W. F. Appelbe, A. P. Ravn
        ACM Transactions on

        Programming Languages and Systems (TOPLAS)
        April 1984

Parnas on information hiding is classic but the examples dated.

    "On the criteria to be used in decomposing systems into modules"
        D L Parnas
        Communications of the ACM, December 1972

Abstraction is not mechanics of coupling, but is about semantics and meaning - designing is creating models that communicate:

    Good vs. Evil: Abstraction
    Manuel Klimek, article on blog
        http://klimek.box4.net/blog/2007/03/18/good-vs-evil-abstraction/

Testability

If you read just one article on testability, Binders old from 12 years ago is the the best I've read. You will have to "translate" concepts to todays terms, and it pretty condensed (but it is at the same time not "being difficult"), read it twice.

    "Design for testability in object-oriented systems"
        Robert V. Binder
        September 1994 Communications of the ACM

The first article I've read that actually talks about testability of software with respect to test creation in a pragmatic way, is Freedman. It is still interesting, although not as current. It's non OO and a bit silly on the math side, especially for a practicioner, but I just skim that...

    Testability of Software components
        IEEE Trans. Software Eng. 17(6): 553-564 (1991)   
        Roy S Freedman

Not so long ago I found an excellent recent summary of testability work, that I could have made good use of earlier. (Note the weird publishing spot.)

    "Predicting Class Testability using Object-Oriented Metrics"
        Magiel Bruntink, Arie van Deursen
        September 2004
        Proceedings of the Source Code Analysis and Manipulation, Fourth IEEE
        International Workshop on (SCAM'04) - Volume 00 SCAM '04

Magiel Bruntinks "Testability of Object Oriented Systems: a Metrics based approach" (dissertation, 2003) is pretty nice as well.

We talked about two basic models of testability, which were kind-of based on Binders categories of fault and conformance directed testing. A model of testability that focuses on fault directed testing is that of Jeffrey Voas. He has published alot, I found this article to be the most accessible:

"Software Testability: The New Verification"
    IEEE Software may 1995
    Jeffrey M. Voas, Keith W. Miller

There are a couple of others worth checking out, this one is ok:

"Factors that affect software testability"
     Voas Jeffrey M.
    October 1991          
    Technical Report
    Publisher: NASA Langley Technical Report Server (available via acm)

Stefan Jungmayr has published alot an+d has focused on dependencies and metrics, this short article sums up alot of his work. Both this and more can be found on www.testability.de/E_index.html:

    "Testability and unit testing"
        Stefan Jungmayr

His dissertation is lengthy, there is some useful stuff there. His clear definitions of dependencies are a good contribution.

Books

If you want a good and accessible text that does cover a lot of the issues we talked about, I really have found good use for Feathers "WELC" book. I recommend it to anyone learning behavior driven or test first design as well.

    "Working effectively with legacy code"
        Prentice Hall, 2004
        Michael Feathers

Chapters addressing test construction factors: Chapter nine and ten talks about controllability and a little about observability. Other chapters talk about design and abstraction, notably chapter 17. Great book on the subject of testing object oriented code, one of the best IMHO.

There's also Binders enormous book, which is not mentioned that often, so I'll mention it. The parts I've read are excellent, but it's quite enormous. He should have split it into several.

    "Testing Object-Oriented Systems: Models, Patterns, and Tools"
        Addison-Wesley 1999
        Robert V Binder

Testing general

I brought up some stuff (the testing periods, etc) from an old article that is really nice, and highly recommended, well worth a read. Short easy read that has many insights, although it is a bit historical.

    The growth of software testing
        D. Gelperin, B. Hetzel
        June 1988, Communications of the ACM,  Volume 31 Issue 6

This is an old classic and still very amusing read, could use another font:
    "In defense of program testing or Correctness proofs considered harmful"
        Andrew S Tannenbaum et al
        ACM SIGPLAN Notices Volume 11 ,  Issue 5  (May 1976)

OO

I mentioned the study on core OO concepts:

    "The quarks of object-oriented development"
        Deborah J. Armstrong        
        Communications of the ACM  archive, February 2006

TOOP - Testable object oriented programming

There has actually been some work on what testable object oriented programming might mean. What I've read has not been terribly interesting, but here is one I read anyway:

    "On testable object-oriented programming"
        Y Wang, et al
        ACM SIGSOFT Software Engineering Notes, July 1997

At the latest AgileØresund meeting we had the usual mix of new and old people representing both devs/techleads and project managers. I (again) wanted to talk about team morale. Being a consultant I get to move between company cultures quite often, which allows me to more easily see and experience differences among them. Having worked for some of the larger traditional companies in Sweden, this is a most fascinating aspect. It is fun to reason about how the company culture has been devised and/or emerged, and what the logic behind it is - what must have been the benefits the leaders saw when promoting some values inside the organization? Morale in a team comes both from the context - from "upwards" if you like - and from within the team. A team needs a vision in order to believe in the work they do. If you do not think that the work you do will matter to anyone at all, then you are not likely to invest heavily in the work. From within the team, a breach of morale will spread: If someone looses faith in the project, that may spread and will at the least affect the others.

I think there is a junction where these things meet; how we express our faith and passion can become a heuristic that is then expected - a mindless rule that the team has to work overtime at some point, that the team has to do this and that. (Well, blindly following rules is almost never good, nothing new there.) This junction is basically where acting and appearances are more important than actual results. Acting and appearances are naturally very important, but are not directly related to the results.

Anyway, Chris mentioned this post from Kathy Sierra (I don't read her blog regularly anymore myself) that talks about the target of passion - company or work. I really see a connection to her post.

Roy blogs about testability in the language. I definitely think that the language could cater testability, much like it connects with other development needs. For example, in .NET there is the obsolete attribute which we may decorate a method with, which causes the compiler to issue a warning if someone compiles code that uses that method.

Likewise, I have for some time wondered if using an attribute indicating that a method is for testing purposes only would be useful. I think so.

Anyway, thanks for this Roy! It's amazing to see how quickly that debate springs up again! I am doing a workshop on testability and encapsulation and this is definitely inspiring, I almost thought that everyone had already gone past the encapsulation debate and that I wouldn't get anyone to discuss it with - but here is proof that it is not so again!

Hopefully we'll get even more perspectives.

There was a project called the Netron project a while  back, that offered a nice graphing library and several related libraries. I used to check the blog regularly, to see progress, and so on. I stopped for a year or more, but not so long ago, I ventured to do so again. I got really suprised, and went to do some checking. Check this adress, you may be surprised to:

http://netron.sourceforge.net/

Don't read on until you've checked it!

Checked it?

Were you surprised? I sure was. If you did not bother to check it, the sourceforge project page has been emptied of all contents (don't know if the source was ever hosted there though, here is someone saying that the CVS repos were removed, which would be very odd indeed). The project homepage link instantly redirects you to an ordering page for a graphing product "Go Diagram". Basically, an ordering page on sourceforge! Odd!

In summary, Netron was an open source project that did not use a well known license, but thelicense was a "use anyway you want" type of thing. It appears to be affiliated with this go diagram commercial venture, but there is no indication of how or why. I don't think there is anything wrong about that, per se. These things feel strange to me, though:

• The redirect from sourceforge to the order page.
• Not leaving a trace of the OS project - after you have accepted donations to the open source project. Check out the thankyou note to "Axel" at the end of this page.

It looks strange, and not pretty. If I had to call it by the looks of things, someone went commercial with the stuff and (perhaps even as insiduously as being part of some agreement?) removed all content they had control over, everywhere (sourceforge, codeproject articles, etc).

Other people have written about this, I wanted to note my own findings here. Do note this posting. There is a resurrection project for the source here, and much of the previously available documentation is hosted here. You can of course browse the archived versions of the homepage, archived codeproject article, and blog. It is strange, isn't it?

(Photo: Tony Richards, Herford)