Category Archives: Extreme Programming

A canonical Repository test

There are only so many ways to test that your persistence layer is implemented correctly or that you’re using an ORM correctly. Here’s my canonical tests for a repository (Java-version):

Very simple. The samplePerson test helper generates actually random people:

If your data has relationships with other entities, you may want to include those as well:

A simple and easy way to simplify your Repository testing.

(The tests use FEST assert 2 for the syntax. Look at FluentAssertions for a similar API in .NET)

(Yes, this is what some people would call an integration test. Personally, I can’t be bothered with this sort of classifications)

Posted in Code, English, Extreme Programming, Java, Unit testing | 5 Comments

Better Scrum sprint planning – look to the demo

After having worked with Scrum for a number of years, I still witness sprint reviews where the team’s demonstration of the product is confusing and the value produced in the sprint is unclear. The demo may consist of just a bunch of different functions and screens without any meaning. Or maybe the team is just talking about what happens behind the curtains in the database. Or maybe the demo just doesn’t display the value that the team was supposed to give to the stakeholders. Most teams have okay demos most of the time, but every now and then, it’s a complete train wreck.

If you’ve experienced a sprint like this, you probably noticed some problems from the very beginning. The sprint planning may have been chaotic and the work during the sprint may have felt purposeless. Chances are that the team was most of the time discussing technical terms that didn’t make much sense to the product owner.

If your team learns to be clear about the sprint goal, you can avoid anemic demos, unstructured planning and undirected work. “But wait”, you may say, “we had a sprint goal and our demo still sucked”. You may think you have a clear sprint goal, but very few teams know what a sprint goal looks like. You may have one, but you might have gotten there by accident.

Here is what a sprint goal looks like: At the end of this period of time, we will demonstrate something to our stakeholders. What we will demonstrate will tell a compelling story that demonstrates real value. We can create the first draft plan of what the demo will look like already at the sprint planning, and we can use this description both to verify our understanding and plan our work.

Let’s say that the product owner says “the goal for the next sprint is to verify the payment solution.” What would a plan for this sprint look like?

At a sprint planning meeting, after the product owner has described the goal, the team plans its work. Then they come back to the product owner to verify that their plan matches the goal. This is what a good plan may sound like: “We will set up so that all users on the web site has a random set of items in their shopping cart. Then we will go to the checkout page. Here, we will see that the shopping cart is displayed in a reasonable way. When we click the payment button, the user will be redirected to the test site for payment provider. We’ll input credit card details and pay. The user will be redirected back to the web site and the web site will display the success or the failure of the payment. We’ll also show the order along with the payment status in a early mockup of the order list page”

The product owner may agree to this sprint plan. If the team knows their technologies well, it is now easy to break this down into tasks, such as “create a shopping cart model”, “display shopping cart page”, “retrieve the payment status from the payment provider” and “store the payment status in the database”.

This demo script will guide the team both during the construction and during the actual sprint review. During the construction a team member is now in a position to solve the sprint goal in the simplest way possible. By focusing on how the team will demonstrate value instead of what technical tasks may or may not be required (e.g. “construct a new order facade service” – whatever that may mean!) we can dramatically cut down on wasteful and convoluted design.

Agile methods emphasize “adapting to change over following a plan”. The same holds true for a demo script. The purpose of the script is not to create a perfect plan (which is of limited value), but to get a clear picture of what we need to create and how we will demonstrate that we have indeed delivered real value.

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If you’re an architect, knowledge is your enemy

When a software architect gets a good idea or learns something new, he has a problem. The main job of the architect is to ensure that the right information in present inside the heads of the people who should build the application. Every new piece of information in the architect’s head represents a broader gap between his brain and that of the rest of the team.

The classical ways of adressing this gap is for the architect to write huge documents or sets of wiki pages. When they realize that there’s not sufficient time set aside in the project schedule for the developers to read all this information, the architect may present the material to developers who sit and nod their heads. But what did they really understand?

Instead of the read-listen-and-nod approach, I prefer an approach that I sometimes call “dragging the information throught the heads of the team and looking at what comes out in the other end.” I provide as little processed information as possible, but instead give the team a structured workshop to uncover and structure the information by asking me or business stakeholders. The outcomes of the workshop should be some tanglible results presented by the team. This result is always different from what I had in mind. Sometimes the difference shows a critical misunderstanding, which allows me to go more in depth in this area. Sometimes the difference represents a trivial misunderstanding or difference in opinion and the architect has the difficult task of accepting a small disgreement without distracting the team. Sometimes, the team has discovered something much smarter than the original idea of the architect.

I find it most useful to do workshops in small groups of three people per group. Each group should produce something that they can show to the whole team afterwards. Here are some examples of workshops that I run:

  • Divide in groups of three with the users/business and the developers represented in each group. Each group should discuss and fill in a template for the vision of the product being created: “For some user who performs some business function the name of system is a type of system which gives a capability related to the task. Unlike most interesting alternative our solution has an important advantage“. The groups get 10 minutes before a debrief with the whole team.
  • Each group then brainstorms a list of users, consumers and others affected by the system and write these on sticky notes. This should be about 20-30 roles. The whole team decides on a few interesting users and the groups then write down for some these: What characterizes the user, what tasks do they perform and what do they value?
  • Based on the list of tasks that stakeholders perform, we create a sketch of a usage flow. I like to refine the documented usage flow with a small task group which takes a few hours to prepare a description of the flow of interaction between the system and external actors
  • Groups of three go through the usage flow to come up with Actors (users and systems), Domain concepts (classes) or Containers (deployment diagram) mentioned or implied in the usage flow and write these on sticky notes. After showing the Actors, Concepts or Containers to the whole group, each workgroup then organizes these on flipcharts to create a Context Model, a Domain Model and a Deployment Model.

Many of these workshops can also be run with distributed groups over video conference and screen sharing.

I like to collect all of these artifacts (vision, users, usage flow, context model, domain model and deployment model) in a PowerPoint presentation so it can be easily showed by the team to external stakeholders. Sometimes someone on the team feel that photographed flipcharts with sticky notes are too informal and decide to draw something in Visio or another fancy tool. This is just a plus.

By asking the team to produce something and present it, rather than explaining the architecture to the team, I ensure that the information is really in their heads and not just my fooling myself by my own understanding.

Posted in English, Extreme Programming, Non-technical, Software Development | 3 Comments

The Rainbow Sprint Plan

Do you ever feel it’s hard to get real progress in a sprint towards the business goal? Do you feel the feedback from a iteration picks on all the details you didn’t mean to cover this sprint? Do you feel like sprint planning meetings are dragging out? Then a Rainbow Sprint Plan may be for you.

Here is an example of a Rainbow Sprint plan:

  1. A customer wants cheap vacations
  2. The customer signs up for daily or weekly notifications of special flight offers
  3. Periodically the System checks which customers should get notifications
  4. The System checks for offers that matches the customer’s travel preference by looking up flights with the travel provider system
  5. The System notifies customer of any matching offers via SMS

    1. Variation: The System notifies customer of any matching offers via email
  6. The customer accepts the offer via SMS
  7. The System books the tickets on behalf of the customer
  8. The system confirms the booking by sending an SMS to the customer
  9. The customer can at any point see their active offers and accepted offers on the system website
  10. The customer enjoys a cheap vacation!

What you can see from this plan:

Use case overview: The plan gives a high-level picture of the next release. We can see how the work we are doing is fitting together and how it ends up satisfying a customer need. This is a requirement technique that is basically Use Cases as per Alistair Cockburn’s “Writing Effective Use Cases“. I’ve been writing use cases at this level for the last three years and found it to be a good way to understand requirements. The trick of good use cases is to stay at a the right level. In this example, each step is some interaction between the system and a user or the system and another system. How this communication is handled is something I find best to leave for an individual sprint.

Iterative completion: Each step has a color code:

  • Black: The team hasn’t started looking into this
  • Red: We have made something, but it’s a dummy version just to show something
  • Orange: We have made something, but we expect lots of work remaining
  • Yellow: We’re almost done, we’re ready to receive feedback
  • Green: Development is complete, we have done reasonable verification and documentation

So the plan accepts that we revisit a feature. As we get closer to the next release, things will move further and further into the rainbow. But we can choose whether we want to get everything to orange first, or whether we will leave some things at red (or even black) while bringing other steps all the way to green.

Demonstration script: When we get to the end of the sprint and demonstrate what we’ve created, this plan gives a pretty good idea of what the demo will look like: We will sign up the customer to a dummy signup page (red), we will register some flights in another dummy page (red), trigger the actual scheduling code (orange), then we will see that an SMS is received on an actual phone (yellow). Then we will simulate an SMS response (orange), see that they system made some communication to a dummy system (red), and send “ok” back as an SMS to the customer (orange). This will focus the team around a shared vision of what to do in this sprint.

I have been thinking in terms of a Rainbow Plan in my last projects, but I’ve never used the term before. I think the plan addresses three of the most common problems that I see in Scrum implementations:

  • The team doesn’t see where it’s going, because user stories are too fine grained to get the big picture. User story mapping and use cases address this, and rainbow plans put it into a sprint-context
  • The team dives into technical details during sprint planning. With rainbow plans, the sprint plan becomes the demo plan which coincides with the requirements.
  • The project has a purely incremental approach, where each feature should be completed in a single sprint. This means that it’s hard to keep the big picture and the product owner is forced to look for even small bugs in everything that’s done in a sprint. With rainbow plans, the team agrees on the completeness of each feature.

May you always become more goal oriented and productive in your sprints.

Posted in English, Extreme Programming, Non-technical, Software Development | Leave a comment

Teaser: Bare-knuckle SOA

I’m working on this idea, and I don’t know if it appeals to you guys. I’d like your input on whether this is something to explore further.

Here’s the deal: I’ve encountered teams who, when working with SOA technologies have been dragged into the mud by the sheer complexity of their tools. I’ve only seen this in Java, but I’ve heard from some C# developers that they recognize the phenomenon there as well. I’d like to explore an alternative approach.

This approach requires more hard work than adding a WSDL (web service definition language. Hocus pocus) file to your project and automatically generating stuff. But it comes with added understanding and increased testability. In the end, I’ve experienced that this has made me able to complete my tasks quicker, despite the extra manual labor.

The purpose of this blog post (and if you like it, it’s expansions) is to explore a more bare-bones approach to SOA in general and to web services specifically. I’m illustrating these principles by using a concrete example: Let users be notified when their currency drops below a threshold relative to the US dollar. In order to make the service technologically interesting, I will be using the IP address of the subscriber to determine their currency.

Step 1: Create your active services by mocking external interactions

Mocking the activity of your own services can help you construct the interfaces that define your interaction with external services.


public class CurrencyPublisherTest {

    private SubscriptionRepository subscriptionRepository = mock(SubscriptionRepository.class);
    private EmailService emailService = mock(EmailService.class);
    private CurrencyPublisher publisher = new CurrencyPublisher();
    private CurrencyService currencyService = mock(CurrencyService.class);
    private GeolocationService geolocationService = mock(GeolocationService.class);

    public void shouldPublishCurrency() throws Exception {
        Subscription subscription = TestDataFactory.randomSubscription();
        String location = TestDataFactory.randomCountry();
        String currency = TestDataFactory.randomCurrency();
        double exchangeRate = subscription.getLowLimit() * 0.9;





        verify(emailService).publishCurrencyAlert(subscription, currency, exchangeRate);

    public void setupPublisher() {

Spoiler: I’ve recently started using random test data generation for my tests with great effect.

The Publisher has a number of Services that it uses. Let us focus on one service for now: The GeoLocationService.

Step 2: Create a test and a stub for each service – starting with GeoLocationService

The top level test shows what we need from each external service. Informed by this and reading (yeah!) the WSDL for a service, we can test drive a stub for a service. In this example, we actually run the test using HTTP by starting Jetty embedded inside the test.


public class GeolocationServiceStubHttpTest {

    public void shouldAnswerCountry() throws Exception {
        GeolocationServiceStub stub = new GeolocationServiceStub();
        stub.addLocation("", "Norway");

        Server server = new Server(0);
        ServletContextHandler context = new ServletContextHandler();
        context.addServlet(new ServletHolder(stub), "/GeoService");

        String url = "http://localhost:" + server.getConnectors()[0].getLocalPort();

        GeolocationService wsClient = new GeolocationServiceWsClient(url + "/GeoService");
        String location = wsClient.getCountryByIp("");


Validate and create the XML payload

This is the first “bare-knuckled” bit. Here, I create the XML payload without using a framework (the groovy “$”-syntax is courtesy of the JOOX library, a thin wrapper on top of the built-in JAXP classes):

I add the XSD (more hocus pocus) for the actual service to the project and code to validate the message. Then I start building the XML payload by following the validation errors.


public class GeolocationServiceWsClient implements GeolocationService {

    private Validator validator;
    private UrlSoapEndpoint endpoint;

    public GeolocationServiceWsClient(String url) throws Exception {
        this.endpoint = new UrlSoapEndpoint(url);
        validator = createValidator();

    public String getCountryByIp(String ipAddress) throws Exception {
        Element request = createGeoIpRequest(ipAddress);
        Document soapRequest = createSoapEnvelope(request);
        Document soapResponse = endpoint.postRequest(getSOAPAction(), soapRequest);
        return parseGeoIpResponse(soapResponse);

    private void validateXml(Document soapMessage) throws Exception {

    protected Validator createValidator() throws SAXException {
        SchemaFactory schemaFactory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
        Schema schema = schemaFactory.newSchema(new Source[] {
              new StreamSource(getClass().getResource("/geoipservice.xsd").toExternalForm()),
              new StreamSource(getClass().getResource("/soap.xsd").toExternalForm()),
        return schema.newValidator();

    private Document createSoapEnvelope(Element request) throws Exception {
        return $("S:Envelope",
                $("S:Body", request)).document();

    private Element createGeoIpRequest(String ipAddress) throws Exception {
        return $("wsx:GetGeoIP", $("wsx:IPAddress", ipAddress)).get(0);

    private String parseGeoIpResponse(Element response) {
        // TODO
        return null;

    private Source toXmlSource(Document document) throws Exception {
        return new StreamSource(new StringReader($(document).toString()));

In this example, I get a little help (and a little pain) from the JOOX library for XML manipulation in Java. As XML libaries for Java are insane, I’m giving up with the checked exceptions, too.

Spoiler: I’m generally very unhappy with the handling of namespaces, validation, XPath and checked exceptions in all XML libraries that I’ve found so far. So I’m thinking about creating my own.

Of course, you can use the same approach with classes that are automatically generated from the XSD, but I’m not convinced that it really would help much.

Stream the XML over HTTP

Java’s built in HttpURLConnection is a clunky, but serviceable way to get the XML to the server (As long as you’re not doing advanced HTTP authentication).


public class UrlSoapEndpoint {

    private final String url;

    public UrlSoapEndpoint(String url) {
        this.url = url;

    public Document postRequest(String soapAction, Document soapRequest) throws Exception {
        URL httpUrl = new URL(url);
        HttpURLConnection connection = (HttpURLConnection) httpUrl.openConnection();
        connection.addRequestProperty("SOAPAction", soapAction);
        connection.addRequestProperty("Content-Type", "text/xml");

        int responseCode = connection.getResponseCode();
        if (responseCode != 200) {
            throw new RuntimeException("Something went terribly wrong: " + connection.getResponseMessage());
        return $(connection.getInputStream()).document();

Spoiler: This code should be expanded with logging and error handling and the validation should be moved into a decorator. By taking control of the HTTP handling, we can solve most of what people buy an ESB to solve.

Create the stub and parse the XML

The stub uses xpath to find the location in the request. It generates the response in much the same way as the ws client generated the request (not shown).

Spoiler: The stubs can be expanded to have a web page that lets me test my system without real integration to any external service.

Validate and parse the response

The ws client can now validate that the response from the stub complies with the XSD and parse the response. Again, this done using XPath. I’m not showing the code, as it’s just more of the same.

The real thing!

The code now verifies that the XML payload conforms to the XSD. This means that the ws client should now be usable with the real thing. Let’s write a separate test to check it:

Yay! It works! Actually, it failed the first time I tried it, as I didn’t have the correct country name for the IP address that I tested with.

This sort of point-to-point integration test is slower and less robust than my other unit tests. However, I don’t find make too big of a deal out of that fact. I filter the test from my Infinitest config and I don’t care much beyond that.

Fleshing out all the services

The SubscriptionRepository, CurrencyService and EmailService need to be fleshed out in the same way as the GeolocationService. However, since we know that we only need very specific interaction with each of these services, we don’t need to worry about everything that could possibly be sent or received as part of the SOAP services. As long as we can do the job that the business logic (CurrencyPublisher) needs, we’re good to go!

Demonstration and value chain testing

If we create web UI for the stubs, we can now demonstrate the whole value chain of this service to our customers. In my SOA projects, some of the services we depend on will only come online late in the project. In this case, we can use our stubs to show that our service works.

Spoiler: As I get tired of verifying that the manual value chain test works, I may end up creating a test that uses WebDriver to set up the stubs and verify that the test ran okay, just like I would in the manual test.

Taking the gloves off when fighting in an SOA arena

In this article, I’ve showed and hinted at more than half a dozen techniques to work with tests, http, xml and validation that don’t involve frameworks, ESBs or code generation. The approach gives the programmer 100% control over their place in the SOA ecosystem. Each of the areas have a lot more depth to explore. Let me know if you’d like to see it be explored.

Oh, and I’d also like ideas for better web services to use, as the Geolocated currency email is pretty hokey.

Posted in Code, English, Extreme Programming, Java | 9 Comments

Use Scrum even if you don’t want to be Agile

An “Agile” project is one that actively seeks to incorporate changes as the project progresses, rather than assuming that the plans from the beginning of the project will work for the whole project duration. Not all organizations want to adopt “agile” as their project metaphor. And some organizations that do adopt methods such as Scrum do it without becoming as “agile” as Scrum promises. Instead of criticizing these organizations of “agile heresy”, I would instead like to offer some useful experience from Scrum, even if the word “agile” doesn’t appeal to you.

Track your progress with small, well-defined milestones: The Product backlog of Scrum is essentially an ordered list of work items. Good backlog elements are either completed or not completed. Partially completed milestones are not counted. A more Agile project will let the product backlog change throughout the project, while a more rigid project may set down the whole backlog at the beginning of the project.

Using a product backlog that is complete ‘up front’ makes your project less agile, but using a product backlog lets you track progress better than most traditional project plans.

Demonstrate progress to stakeholders: The earlier a project gets feedback on the work it has completed, the better it is able to anticipate and deal with misunderstandings. The expectations of stakeholders is often misunderstood until everyone can actually see what is being constructed. Scrum requires Sprint reviews at regular intervals of a couple of weeks to demonstrate progress. A project with less communication with the stakeholders may have fewer and less regular reviews, but every review you do have will reduce your risk.

Communicate daily within the team: Just as there will be misunderstanding between the project and the stakeholders about the proper outcomes, there will be misunderstandings within the team about the proper strategies to complete the project. Scrum requires a daily standup meeting to enforce communication within the team. Other teams may be geographically distributed, dislike the ritual of the standing meeting or work on non-overlapping tasks and decide that they need less communication.

Regardless of the form or frequency of communication within the team, the project should evaluate whether they are making repeated mistakes because of lack of shared knowledge and awareness. And whether their rituals waste or preserve the time of the team.

Make decision making explicit: In Scrum, the decisions about what the team should work on rests with a single individual: The Project owner. Many organizations cannot invest the authority that this role implies with a single individual, or cannot find an individual with both the business understanding and the technical knowledge to make confident evaluations.

Regardless of whether the authority rests with a single individual, a project needs to make decisions about what it should create and in what order. Identifying who needs to be involved in these decisions will make the project run more smoothly.

You don’t need to “drink the Agile cool aid” to benefit from the experience of Scrum over the last 20 years. And many projects that profess being Agile just be using the rituals from Scrum within an old mindset. You will not get the same benefits from Scrum as a truly agile team, but that doesn’t mean it’s not right for you.

Posted in English, Extreme Programming, Software Development | 8 Comments

What is a “commitment” anyway?

I hate giving promises for things I can’t control. I can promise that I will attend a party or that I will set aside time to help you with your problem. I cannot promise that the party will be fun or that your problem will be solved. Giving promises on effort is honest, giving promises on outcomes is dishonest.

A team that commits to an estimate is promising something they cannot control. A team that is blamed for giving an estimate that is too low can easily avoid that particular mistake next time around. And given the law that work expands to fill available time, the estimate will never be too high. The result is cost spiraling up.

What if we assumed that estimates would never be particularly reliable. And if we assumed that forcing a team to commit to an estimate is unreasonable behavior? How would we act in a world where that’s true?

Let’s imagine we live in a world where the product owner cannot ask for an estimate. What can the product owner do instead?

The product owner can say “stop working on this story if you’ve spend more than 40 hours. Or if you think you will end up spending more than 40 hours.”

Such a limit can be viewed as a budget.

The product owner can make a bet on how many user stories the team will complete by looking at what they have done before. If the consequence of the betting wrong are severe, the product owner can be cautious about the number of user stories. (Bonus question: Is the team is a better or worse position to know the consequences of betting wrong?)

Such a bet can be viewed as a forecast.

The team, on the other hand can commit to working according to the agreed-upon rules. They can commit to do things in the order set by the product owner. They can commit to doing the best job they can within the time budget the product owner has allocated.

We commit to effort, not to outcomes.

Posted in English, Extreme Programming, Software Development | 13 Comments

How to GROW a user story

As a user, I can add social security number, so patient logs have social security numbers

As a developer, how would you react if you were given this user story? Would you throw it back in the face of the product owner, or would you try and understand it?

How about the following dialogue?

  • Developer: “What are we hoping to achieve with this story?”
  • Customer: “We hope that the patient logs will have social security numbers. Duh.”
  • Developer: “Sorry, I was unclear: What problem do you experience now that we don’t have the social security number?”
  • Customer: “Oh! We need the social security number when we bill the customer.”
  • Developer: “I see. So what happens now?”
  • Customer: “Well, since the patient has left the hospital, the billing department has to phone or send postal mail to get the information. That’s a lot of work.”
  • Developer: “What places in the application can we add this information?”
  • Customer: “We’ll add it to the patient journal.”
  • Developer: “Who updates the patient journal, and when?”
  • Customer: “Whops. The doctor updated the journal after the patient has left. We better add it when secretary checks the patient out. So that would be in the appointment system”
  • Developer: “What other places could we enter this information?”
  • Customer: “Well, we could have a field for the social security number when the patient first requests the appointment”
  • Developer: “So, we have considered two options: The appointment system at checkout or the appointment system when the appointment is booked. What other ways could we get the same information?”
  • Customer: “We could collect it from the governmental web service, I suppose.”
  • Developer: “What would you like us to try first?”
  • Customer: “Since the patient normally fills in the appointment request themselves, let’s try that out first.”
  • Developer: “Let’s see if I get you correctly….”

In order to have the required information to send an invoice, as the billing department, I want the patient to enter their social security number when they request an appointment

What you’ve just witnessed is a series of questions that can be organized like this:

  • Goal: What are we hoping to achieve? How will the user story change the world?
  • Reality: How are things working now?
  • Options: What else could we do instead? In addition?
  • Will: What will we do? What is our plan of action

The GROW mnemonic is a tool from professional coaching. That is: Talking to people about the problems and ambitions in their professional and private lives. It helps guide a novice coach through a coaching conversation and focus on the problems of the person being coached. Or, in this case: On the business value we want to achieve.

At the end of the day, as a developer you will be judged not on whether you followed the orders you were given, but whether you understood and delivered what was really needed. By asking your users, your product owner or your domain expert what they really, really want (Goal), it will be easier for you achieve. And if you don’t have access to the relevant people, these questions can still help you guide your thinking about the requirements.

You can read more about the GROW model at and many other websites devoted to helping people get to the best of their ability.

A big thank you goes to Antti Kirjavainen for suggesting the patient journal example and for coaching me in the process of writing this article.

Posted in English, Extreme Programming, Software Development | 2 Comments

The Architecture Spike Kata

Do you know how to apply coding practices the technology stack that you use on a daily basis? Do you know how the technology stack works? For many programmers, it’s easy enough to use test-driven development with a trivial example, but it can be very hard to know how to apply it to the problems you face every day in your job.

Java web+database applications are usually filled to the brim with technologies. Many of these are hard to test and many of these may not add value. In order to explore TDD and Java applications, I practiced the Java EE Spike Kata in 2010. Here’s a video of me and Anders Karlsen doing this kata at JavaZone 2010.

A similar approach is likely useful for programmers using any technology. Therefore, I give you: The rules of the Architecture Spike Kata.

The problem

Create a web application that lets users register a Person with names and search for people. The Person objects should be saved in a data store that is similar to the technology you use daily (probably a relational database). The goal is to get a spike working as quickly as possible, so in the first iteration, the Person entity should probably only contain one field. You can add more fields and refactor the application later.

The rules

The most important rules are Robert Martin‘s three rules of Test-driven development:

  • No code without test (that is, the code should never do something that isn’t required in order to get a test to pass)
  • Only enough test to get to red (that is, the tests should run, give an error message and that error message should correct)
  • Only enough code to get to green (that is, the tests should run and not give an error)
  • (My addition: Refactor on green without adding functionality)

Secondly, application should be driven from the outside in. That is, your first test should be a top-level acceptance test that tests through http and html. It’s okay to comment out or @Ignore this test after it has run red for the first time.

Lastly, you should not introduce any technology before the pain of not doing so is blinding. The first time you do the kata in a language, don’t use a web framework beyond the language minimum (in Java, this means Servlets, in node.js it’s require('http'), in Ruby it means Rack). Don’t use a Object-Relational Mapping framework. Don’t use a dependency injection framework. Most definitely don’t use an application generator like Rails scaffold, Spring Roo or Lift. These frameworks can be real time savers, but this kata is about understanding how the underlying technology works.

As a second iteration, use the technologies you use on a daily basis, but this time set up from scratch. For example, if your project uses Hibernate, try configuring the session factory by hand. By using frameworks in simplest way possible, you’ll both learn more about what they bring to the table and how to use them properly. For complex technology like Hibernate, there’s no substitute for deeper understanding.

What to expect

So far, I’ve only done the Architecture Spike Kata in Java. But on the other hand, I’ve done it around 50 times together with more than ten other developers. I’ve written about how to get started with the Java EE Spike Kata (in Norwegian) on my blog before.

This is what I’ve learned about working with web applications in Java:

  • Most Java web frameworks seem to harm more than they help
  • Hibernate is a bitch to set up, but once it’s working, it saves a lot of hassle
  • Using TDD with Hibernate helped me understand how to use Hibernate more effectively
  • I’ve stopped using dependency injection frameworks (but kept on using dependency injection as a pattern)
  • I have learned several ways to test web applications and database access independently and integrated
  • I no longer have to expend mental energy to write tests for full stack application

The first time I write this kata with another developer, it takes around 3 to 5 hours, depending on the experience level of my pair. After running through it a few times, most developers can complete the task in less than an hour.

We get better through practice, and the Architecture Spike Kata is a way to practice TDD with the technologies that you use daily and get a better understanding of what’s going on.

Posted in English, Extreme Programming, Java, Software Development | 1 Comment

How to start a Coding Dojo

I recently attended the XP Days Ukraine conference in a rainy, but beautiful and Christmas-decorated Kiev. I conducted a coding dojo and gave a talk where I demonstrated pair programming live together with Dima Mindra. After the talk, I got a few questions about how to run a Coding Dojo.

This article is meant as a guide to anyone wanting to start up a Coding Dojo, whether it’s in Kiev (Mikail/Aleksey), in Odessa (I’m looking at you, Dima!) or anywhere else in the world.

A Coding Dojo is a place to learn and have fun while programming

Quite simply, a Dojo is a gathering of programmers who come together to have fun and learn while programming. It’s always hands-on and it’s always social. In Oslo there are about 300 people who have signed up their interest. We meet on average once per month, usually in a bar. There is anywhere from 5 to 25 people who attend any given meeting.

Alternatively, a Coding Dojo can be used to describe a single event for a company or team that wants to train their developers in a hands-on and engaging way.

Coding Dojo Style #1: Many programmers, one problem

In the martial art Aikido, “Randori” means that multiple people are attacking the same person. In the Coding Dojo, “Randori” means that multiple programmers are attacking the same problem.

In order to organize a randori-style dojo, you need a computer with a development environment, a projector, a place to meet, a facilitator and 4-10 programmers who attend. Here is one way to carry out a Randori Style Coding Dojo:

  • If the group is new to test-driven development, the facilitator demonstrates the red-green-refactor cycle with a simple example (no more than 10 minutes)
  • The facilitator introduces the programming problem (kata) to solve. The Prime Factors kata is a good first kata for a group
  • The faciliator invites a partner to join him at the keyboard. The facilitator writes a first test, makes sure it runs red and invites someone else from the group to take his place.
  • Each pair works on the problem for 5-10 minutes, the facilitator then makes sure that one person in the pair is switched out with someone in the audience.
  • After about 45-60 minutes of working on the problem, call a break and review what’s happened. Personally, I’ve had success with asking everyone to name one thing that they learned, one thing that surprised them, and one thing they want to change about the way they work.
  • After the review, the group can work on another kata (problem), try the same problem again or use another exercise form

The biggest barrier for most people to participate in a Coding Dojo is that most programmers have never programmed live in front of anyone else. This feels extremely awkward and vulnerable at first. As a facilitator, your most important job is to help everyone feel at ease at whatever level they are.

Coding Dojo Style #2: Pairs working in parallel

Some people report that a Randori-style dojo can feel slow and constrained. As an alternative, I sometimes use the CyberDojo software, created by Jon Jagger. For a CyberDojo style dojo, you need a place to meet, a computer with a projector and internet access, a facilitator and 6-30 programmers with their own laptops with a web-browser and internet access. Here is how I usually carry out a CyberDojo style Coding Dojo:

  • The group forms pairs of programmers
  • The facilitator sets up a CyberDojo on (It may be smart to send a quick tweet to Jon to make sure he’s not planning to restart the server at this time)
  • All the pairs work in the fashion the group has agreed to work for 30-60 minutes
  • After the coding session, the facilitator uses the CyberDojo dashboard as a focus for discussions of programming habits

If you’re thinking about facilitating a Cyber Dojo, just go to, try creating a dojo and solve a kata. You can do this on your own now!

Coding Dojo Style #3: Working under stress

Extreme startup is a workshop based around a server that will ask questions of the software running on the computer of each participating pair. As the pairs answer questions correctly, they are awarded points. I usually run an Extreme Startup session after having run a strict TDD Coding Dojo. In the Extreme Startup, teams can work any way they want.

The Extreme Startup software is developed by Matt Wynne and Richard Chatley. There are several forks, including mine, which tries to maximize the stress.

In order to run an Extreme Startup workshop, you need a place to meet, a computer with a projector and the Extreme Startup software, a facilitator and 6-30 programmers with their own laptops with a development environment of their choice. All the computers need to be on a shared network so they can communicate using TCP/IP.

  • The group form pairs. If someone wants to work solo, or in bigger groups, that is okay, too
  • The facilitator starts the Extreme Startup software in warmup mode
  • The facilitator demonstrates how to get started (I use this collection of starting points in a number of languages)
  • The teams work for around 30 minutes until (almost) everybody have been able to get a web server running and registered on their computer
  • The facilitator starts the Extreme Startup software in real mode
  • All the teams reregister their servers. All hell breaks lose as they try to implement the questions as fast as they can
  • After the teams have worked for another 60 minutes, the facilitator breaks off the competition. Ask the teams on the top to describe how they worked

If you’re thinking about facilitating an Extreme startup, download my or Richard Chatley’s version of the software to your computer. The README file explains how to get it running. Then download Steria’s collection of starting point to your computer. Use the ruby/sinatra_for_dummies starting point to create a solution. Let me know of your experiences when trying out the software, so I can improve the README.

You can do this by yourself now!

Start a coding dojo

A coding dojo is a great way to build your professional network, become a better programmer, and to have fun! I hope this article can help you get started.

Posted in Communities, English, Extreme Programming, Pair programming | 7 Comments