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Busy Programmers Guide on Where to Buy eBooks

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Every Programmer needs to read books. Usually you would get some packages from Amazon (or your favorite retailer) and read through them. Now with devices like the Kindle and iPad (and Nook and…) things will change. No more carrying around a couple of hundred pages of paper. Only some Megabytes on Gigabytes of storage. The displays nowadays are good enough and the battery is not a problem for the most part.

Now the tricky part, you want your books in a format which you can read on many devices. The obvious candidates are:

How to Detect if Your Server Is Down When Making jQuery Ajax Calls

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If you developed an ajax rich web application, maybe even a single page interface, you want to make sure that the user gets notified if the server is not reachable anymore. This happens either if the it goes down or the client loses its network connection. Depending on your code the application can run for a while and the user is confused about missing interactivity.

So how do you detect this? jQuery offers an error callback if something with the call goes wrong.

Lightweight Web Prototyping for the Framework Loving (Java) Developer

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A couple of month ago I had an idea for a small web app. But what does it take to do it ? Do you start with the back end or the front end (read server or client side) ? Typically I would start at the back end, get the domain right and then see how I can fit the UI in. If a programmer starts this way you end with the typical ‘the programmer did the GUI’ scenario. That’s not really what I wanted. Don’t think too much about the domain, just see what the needs of the end user are and get the UI done (right).

How We Switched From Subversion to Git

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So I heard about these strange distributed version control systems like over a year ago. I used it in my own little projects and everything went smoothly and I really liked it. The idea also caught on at work and my team started a using Git in a fresh project last summer. We did not had so much problems since you can use Git very much like a central vcs like Subversion if you want to.

Still, for all other code, we used Subversion. We believe in agile and feature branches, so that’s what we do a lot. Every story has its own branch. If one story touches multiple code bases, that means multiple merge down/copy up’s.
At some point, in preparation for a sprint review, we found that code had disappeared from the trunk. Everything seems to work perfectly, just this feature was missing. Usually you would think if code was deleted, there would be at least one test failing and telling you that something is missing. But no, typing one wrong version number during merge down/copy up cut out the story very cleanly. Once we found the problem we could merged it back in from the not yet deleted feature branch. Overall we managed to work with Subversion but it was a growing pain since we knew there was something better.

There are several advantages of distributed version control system which you all might have heard of already so I won’t go in to detail of this (of course there is also one major disadvantage: complexity). The main advantages for me are:

5 Code Metrics You Need to Watch

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Developing software ain’t easy.

How do you know how you are doing ?

You could start collecting metrics about your code. These can give you some indication how maintainable and reliable it is.

The metric which come to mind to the most people is code coverage. Some people say it must be near 100%, other say 80% is a good number. At the end it can’t tell you if you are doing great or good. The only thing you might read from it is that a low number indicates a potential problem.

Name Your Objects Right

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No Name

Whenever you create an object you have to find a meaningful name.

While renaming later in modern IDE’s is no problem at all you should not pick the first name which comes to your mind.

Imagine you have an external fraud detection web service and it will return a ‘hit’ or ‘miss’. How do you name this object? HitOrMiss maybe (since this is the representation you get from the webservice) ? It might describe the problem at hand. If you go with this name it will dripple down through all layers. The domain model, the dto’s, services and more will now reference to this object (and create their own derivates for it). Your colleagues which code up other parts of the system will refer to it and create their own variants of the name (like structure for web pages). The wrong name is now all over your code.

So much for refactoring in your IDE. You will never catch all the places automatically where the wrong name was used.

While it seemed lost time discussing the ‘right’ name for 5 minutes in the beginning it saves you much more time afterwards. Of course you might get also confused a couple of weeks later remembering what this thing really does and what it is used for.

Make sure you take time in naming your objects. A wrong decision can do some harm to your code. The later it turns out that the name was not correct the much more expensive it becomes to correct this mistake. If you are not really sure how to name it, talk to your colleagues and discuss the name. A second opinion can not hurt.

Maybe FraudDetectionResult would have been a better choice.

One Year of Blogging

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© Mrs Logic @ flickr

One year ago I started to blog again. Time for a little recap.

Why did I do it ?

I use this blog to write down my own thoughts about software and development. This is for my own reference but also it is a little way to give something back to the world wide community in return for all the useful stuff I do read on the net.

I noticed how this also made me a better programmer. Try it out by yourself. Having a professional blog is also a good way for Personal branding.

Stats for the last 12 months

I love number so here they are:

About 15.000 unique visitors About 20.000 pageviews

Traffic

20.64 % Direct Traffic 36.34 % Referring Sites 42.44 % Search Engines

Highest page views on one day: the Selenium 2 post, 620 pageviews (ok, this was big link of the day at dzone.com).

Countries

I had visitors from 120 countries.

3362 visitors from United States 2090 visitors from Germany 776 visitors from United Kingdom

Top posts

GeoLocation with HTML5 2670 pageviews JSF 2 and maven 2607 pageviews Selenium 2 and Concordion vs. Cucumber each 1566 pageviews

I have 142 RSS subscribed readers.

All in all, not too shaby ;-).

Thanks

Thanks to everybody for reading my thoughts. Thanks for the comments and hints.

I’m looking forward to the next year. It is going to be a great one.

What’s Your Preferred Development Infrastructure Stack?

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In Response to Matt Raible’s question about my preferred development stack.

Source control

In my own development project I switched to Git some time ago. I was using svn and before that cvs for a couple of years. Git just makes it easy to try out small ideas very quickly without reverting the code. We will introduce Git at work pretty soon (I hope).

The Atlassian cloud

I was using Confluence as a Wiki in my open source project and my current employer Hypoport uses it as well. Bug tracking is pretty much a task of Jira. Those two integrate very nicely. You can have ping backs in your Jira Ticket from Confluence, so you see all related files. I would love to use FishEye but I’m not sure how to justify the costs and what the added value is in our case.

The Code

I’m pretty much sold to Jetbrains IntelliJ Idea. I’m using it for 5 years now. With it comes Teamcity. It’s a very nice continuous integration tool where the biggest plus (among other things) is the delayed (and pre tested) checkin. No more late night checkins which break the master. We just rolled out the latest version which has a much nicer Git integration (so we can make the switch).

So it comes down to:

The List

  • Source control: Git
  • Wiki: Atlassian Confluence
  • Continuous Integration: Jetbrains Teamcity
  • Bugtracker: Atlassian Jira

We are about to use Sonar for code analysis and development over time, but this is just in the beginning.

What’s yours ?

Using Selenium2 for Web Testing (and Not Selenium IDE)

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Selenium IDE

Selenium is well know for automatic testing web pages. It does support many browsers, operating systems and languages. A Selenium IDE exists to aid you creating automated tests.

Selenium

It is possible to write extensions in JavaScript to have data driven tests. If you organize your selenium tests in a way that you split the pages and forms in components, you can load up new data for the tests (written in xml) to fill out forms differently for each use case. The Selenium IDE will be of a great help here since you start develop the tests in the IDE and later ‘just’ parametrize the pages. With a couple of more javascript magic you can run these as well in Selenium Remote Control (Selenium RC for short). This even works for running the tests in continuous integration systems like Hudson or Teamcity.

Great Stuff.

The problem.

The drawback coding up your tests with the Selenium IDE is: HTML.

You will end up with some test suites including many test scenarios. It will be one big ball of

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<tr>
  <td>type</td>
  <td>accountnumber:Value</td>
  <td>82892892811</td>
</tr>
<tr>
  <td>type</td>
  <td>accountAmount:Value</td>
  <td>2345.33</td>
</tr>

You will build components and you will end up with GotoIf and Label statements. Back to Basic programming from the 80ties. Without more javascript extensions you also can’t reuse combinations of scenarios.

While this works pretty ok: I’m a programmer and do have a problem with the quality of the produced code. It’s easy to mess up. It’s not safe for refactoring. To extend functionality you need to have javascript knowledge. Depending on your company profile (e.g. java shop) , this might be a problem. Having a dedicated tester on the team certainly helps to overcome these obstacles, but if everybody in the team just once in a while looks into the Selenium IDE tests, the quality and the reliability of the code will not improve. Not to mention all the copy and paste. Been there, done that.

Selenium 2

A much nicer approach for me would be something like this:

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WebDriver driver  = new FirefoxDriver();
AppWebTest test = new AppWebTest(driver, "http://myapp.com/login");
LoggedInUser user = test.login("user", "password");
Account account = user.createNewAccount("DemoAccount");
account.addPerson(PersonFactory.createPersonWithNoIncome());
...
account.verify();

This would log in a user, creates an account and assigns a person to it. Everybody could read and understand it. Furthermore you can easily reuse components and logic. I would imagine that creating a DSL, matchers and finders is everything one would need to have a very nice test scenario.

All that is already possible with Selenium 1 and the language bindings (more or less).

Just with the release of the first alpha of Selenium 2 mid december 2009 it became just a little bit easier.

Selenium 2 is the combined effort of Google’s Webdriver and Selenium. Webdriver tries to tackle Seleniums problems with Javascript and the security model as well as the complex Selenium RC API.

Selenium is written in JavaScript which causes a significant weakness: browsers impose a pretty strict security model on any JavaScript that they execute in order to protect a user from malicious scripts. … Additionally, being a mature product, the API for Selenium RC has grown over time, and as it has done so it has become harder to understand how best to use it. For example, it’s not immediately obvious whether you should be using “type” instead of “typeKeys” to enter text into a form control. Although it’s a question of aesthetics, some find the large API intimidating and difficult to navigate.

Webdriver does not use JavaScript to control the web browser but uses native controls, e.g. an extension for Firefox or the native automation extensions of IE. Furthermore it introduces an object based API instead of following Seleniums directory based approach.

So given the above example the login method would look something like this:

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 public LoggedInUser login(String userName, String password) {
    driver.get(url);
    driver.findElement(By.id("user")).sendKeys(userName);
    driver.findElement(By.id("password")).sendKeys(password);
    driver.findElement(By.id("login")).click();

    LoggedInUser user = new LoggedInUser(driver);

    WebElement startPage = driver.findElement(By.id("startPage"));

    assertThat(startPage().getText()).isEqualTo("Start");
    return user;
  }

You can take this to any level. It took me just a few hours to model the above use case with componentized input elements.

With a bit more abstraction addPerson looks something like the following code. Whatever is needed to add a person to an account will be replayed. This is what Selenium IDE would normally do.

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public void addPerson(Person person) {
    jumpToAccountOverView();
    clickOnLink("menu:Overview");
    clickOnLink("table_personTable:link_newPerson");

    inputGuiElement(person.getTitle());
    inputGuiElement(person.getLastName());
...
    clickSave();

And now for the best part. You don’t really need a real web browser. Selenium 2 supports 4 WebDriver:

  • Firefox
  • Chrome
  • Internet Explorer (on Windows)
  • HtmlUnit

HtmlUnit

With enabled JavaScript on HtmlUnit (it uses Rhino, so not all JavaScript tricks might work, could be a drawback depending on your scenario) I can run my test as TestNG or JUnit test case. No need for a Selenium RC anymore. No browsers running locally or on remote machine listing to ports to execute tests and transmitting results back.

It is very useful to have the Selenium RC take screen shots during it’s run. Selenium 2 can’t do this right now (and with HtmlUnit never can). But by simply integrating some logging in the components and elements and you know right away where things went wrong. Developing with the Selenium IDE might seem like a must, but during the work on my prototype all I needed was Firebug and a XPath Searcher. I did not miss it at all. To do integration tests you could test all components independently and one at a time. Once these work, chain them together and let them run as unit tests. Did I mention HtmlUnit is fast ?

Conclusion

I barely dug into the webdriver code, I played around with it for a couple of hours and I’m sure there more is stuff (and bugs) to find. Given that Selenium 2 is in alpha 1 stage right now I expect very nice things coming out of it. It certainly looks like the way to go.

Another strong contender is Canoo WebTest. I will have a look at this one in another post.

Update Ajax and HtmlUnit 1/5/2010

It does not seem to work. You need a real browser to get dynamically content re-rendered through Ajax.

A method waiting for an id to be rendered (or timeout after x seconds) could look like this:

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  public void waitForElementOrTimeout(String idToWaitFor, int timeout) {
    long end = System.currentTimeMillis() + timeout * 1000;
    RenderedWebElement resultsDiv = null;
    while (System.currentTimeMillis() < end) {
      try {
        resultsDiv = (RenderedWebElement) driver.findElement(By.id(idToWaitFor));
      }
      catch (NoSuchElementException e) {
        // 
      }
      if (resultsDiv != null &amp;&amp; resultsDiv.isDisplayed()) {
        break;
      }
    }
    assertThat(resultsDiv).isNotNull();
  }

This will either find the element specified or throw an assertion (updated example from the selenium 2 page).

Story Based Daily Stand-up Meeting

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© royskeane@flickr

We are agile. We do Scrum. We do daily Stand-ups.

A couple of weeks ago we changed our daily stand-up meeting. Our Scrum master came up with the idea to not go around the whole team and everybody talks about what he has done, what he will do and what the impediments are but to make it story based.

Usually after a break down everybody was working on one story, saw the task cards and made sure he did the things he was supposed to do. But this is not enough. You need to have an overview of the whole story (and the sprint). Only with that knowledge you can make sure you will meet the commitment.

So what we started to do is a stand-up meeting based on stories. Every story has a story owner. This is either the person who first started on this story or somebody who is expert in the field worked on. Every morning he is giving a review of how ‘his’ story is progressing, where the problems are and how he could need help. Depending on the priority he gets everything he needs. After presenting the status to the whole team every team member involved gives a smiley on how he feels about the story and the sprint. This way everybody knows what the situation is and how the sprint is progressing.

We found this very effective and it gives every team member a much better feeling about our commitment.

You should try it too.