The Holy Java

Building the right thing, building it right, fast

Archive for January, 2012

Most interesting links of January ’12

Posted by Jakub Holý on January 31, 2012

Recommended Readings

  • Jeff Sutherland: Powerful Strategy for Defect Prevention: Improve the Quality of Your Product – “A classic paper from IBM shows how they systematically reduced defects by analyzing root cause. The cost of implementing this practice is less than the cost of fixing defects that you will have if you do not implement it so it should always be implemented.” – categorize defects by type, severity, component, when introduced; 80% of them will originate in 20% of the code; apply prioritized automated testing (solve always the largest problem first). “In three months, one of our venture companies cut a 4-6 week deployment cycle to 2 weeks with only 120 tests.”
  • Ebook draft: Beheading the Software Beast – Relentless restructurings with The Mikado Method (foreword by T. Poppendieck) – the book introduces the Mikado Method for organized, always-staying-green (large-scale) refactorings, especially useful for legacy systems, shows it on a real-world example (30 pages!), discusses various application restructuring techniques, provides practical guidelines for dealing with different sizes of refactorings and teams, discusses in depth technical debt and more. To sum it up in three words: Check it out!
  • Daily Routine of a 4 Hour Programmer (well, it’s actually about 4h of focused programming + some hours of the rest) – a very interesting reading with some inspiring ideas. We should all find some time to follow up the field, to reflect on our day and learn from it (kaizen)
  • The Agile Testing Quadrants – understanding the different types of tests, their purpose and relation by slicing them by the axis “business facing x technology facing” and the axis “supporting the team x critiquing the product” => unit tests x functional tests x exploratory testing x performance testing (and other). It helps to understand what should be automated, what needs to be manual and helps not to forget all the dimensions of testing.
  • Adam Bien: Can stateful Java EE apps scale? – What does “stateless” really mean? “Stateless only means, that the entire state is stored in the database and has to synchronized on every request.” “I start the development of non-trivial (>CRUD) applications with Gateway / PDOs [JH: stateful EJBs exposing JPA entities] and measure the performance and memory consumption continuously.” Some general tips: Don’t split your web server and servlet container, don’t use session replication.
  • Brian Tarbox: Just-In-Time Logging – How to remove 90% of worthless logs while still getting detailed logs for cases that matters – the solution is to (1) only add logs for a particular “transaction” with the system into a runtime structure and (2) flush it to the log only if the transaction fails or st. else significant happens with it. The blog also proposes a possible implementation in detail.
  • DZone’s Top 10 NoSQL Articles of 2011
  • DZone’s Top 5 DevOps Articles of 2011
  • Test Driven Infrastructure with Vagrant, Puppet and Guard – this is interesting for me for I’m using Vagrant and Puppet on my project to create and share development environments or their parts and applying test-first approach to it seems interesting as do also the tools, rspec-puppet, cucumber-puppet and Guard (events triggered by file changes) and referenced articels.
  • 5+1 Sonar Plugins you must not miss (2012 version) – Timeline Plugin (with Google Visualization Annotated TimeLine), Useless Code Plugin, SIG Maintainability Model Plugin (metrics Analysability, Changeability, Stability, Testability), Quality Index Plugin (1-number health indicator), Technical Debt Plugin

Links to Keep

Clojure Corner

  • ClojureScript One Guide – “ClojureScript One shows you how to use ClojureScript to build single-page, single-language applications in a productive, effective and fun way.”
  • Asynchronous workflows in Clojure - true asynchronous (non-blocking) network access in Clojure with Netty/the Lamina project.
  • Clojure 2011 Year in Review – a list with important events in the Clojure sphere with links to details – C. 1.3.0, ClojureScript, logic programming with core.logic, clojure-contrib restructuring, birth of 4Clojure and Avout.
  • Clojure Atlas – interesting project (alpha version) presenting Clojure documentation in the form of interactive graph of related concepts and functions; it’s far from perfection but I like the concept and consider paying those ~ $25 for the 1.3.0 version when its out (however, the demo is free and it might become open-sourced in 2012)

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Troubleshooting Jersey REST Server and Client

Posted by Jakub Holý on January 31, 2012

The logging in Jersey, the reference JAX-RS implementation, is little sub-optimal. For example if it cannot find a method producing the expected MIME type then it will return “Unsupported mime type” to the client but won’t log anything (which mime type was requested, which mime types are actually available, …).  Debugging it isn’t exactly easy either, so what to do?

Well, I don’t know the ultimate solution but want to share few tips.

Read the rest of this entry »

Posted in Languages | Tagged: , , | 1 Comment »

How to Create Maintainable Acceptance Tests

Posted by Jakub Holý on January 18, 2012

This post summarizes what I’ve learned from various sources about making acceptance or black-box tests maintainable. This topic is of great interest to me because I believe in the benefits that acceptance tests can bring (such as living documentation) but I’m also very much aware that it is all too easy to create an unmaintainable monster whose weight eventually crushes you. So the question is how to navigate the minefield to get to the golden apple?

The key elements that contribute to the maintainability of acceptance tests are:

  1. Aligned business, software, and test models => small change in business requires only a similarly small change in the software and a small change in tests (Gojko Adzic explains that very well in his JavaZone 2012 talk Long-term value of acceptance tests)
    • The key to gaining the alignment is to use business language in all the three models from the very start, building them around business concepts and relationships
  2. Testing under the surface level, if possible
    • Prefer to test your application via the service layer or at worst the servlet layer; only test on the UI level if you really have to and only as little as possible for UI is much more brittle (and also difficult to test)
    • The more you want to test the more you have to pay for it in the terms of maintenance effort. Usually you decide so that you cover the part(s) of the application where the most risk is – the best thing is to do cost-benefit evaluation.
  3. Isolating tests from implementation by layers of test abstraction
    • Top layer: Acceptance tests should only describe “what” is tested and never “how” to test it. You must avoid writing scripts instead of specifications.
    • Layer 2: Instrumentation – right below the acceptance test is an instrumentation layer, which extracts input/output data from the test and defines how to perform the test via a high-level API, provided by the next level (we could say a test DSL) such as “logInUser(X); openAccountPage();”
    • Layer 3: High-level test DSL: This layer contains all the implementation details and exposes to the higher layer high-level primitives that it can use to compose the tests without depending on implementation details (ex.: logInUser may use HtmlUnit to load a page, fill a form, post it). See the PageObject example below.

(And of course many, if not all, of the rules for creating maintainable unit tests apply as well.)

Read the rest of this entry »

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Visualize Maven Project Dependencies with dependency:tree and Dot Diagram Output

Posted by Jakub Holý on January 13, 2012

The dependency:tree goal of the Maven plugin dependency supports various graphical outputs from the version 2.4 up. This is how you would create a diagram showing all dependencies in the com.example group in the dot format:

mvn dependency:tree -Dincludes=com.example -DappendOutput=true -DoutputType=dot -DoutputFile=/path/to/output.gv

(The output is just a text file with the extension Graphviz gv.)

To actually produce an image from the dot file you can use one of dot renderers, f.ex. this online dot renderer (paste into the right text box, press enter).

You could also generate the output f.ex. in the graphml format & visualize it in Eclipse.

Note: Thanks to the reader Not Relevant for pointing out the right extension and a typo.

Posted in Tools | Tagged: | 4 Comments »

Key Lessons from the Specification by Example Course, Day 1

Posted by Jakub Holý on January 9, 2012

I’m taking part in a course of Specification by Example, lead by Gojko Adzic. Here I want to summarize the key things I’ve learned in the first day of this entertaining and fruitful course thanks to both Gojko and my co-participants.

If you haven’t heard about Specification by Example (SbE) before (really?!), then you need know that its main concern is ensuring that you build the right thing (complimentary to building the thing right), which is achieved by specifying functionality collaboratively with business users, testers, and developers, clarifying and nailing them with key examples, and finally, where it is worth the effort, automating checks of those examples to get not only automated acceptance tests but, more importantly, a “living documentation” of what the system does that never gets out of date. Best to read the key ideas described by Gojko himself or the SbE Wikipedia page. Read the rest of this entry »

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Posted by Jakub Holý on January 9, 2012

Some guy from uCertify, which offers preparation kits for various programming exams in Java and other areas, asked me to review their PrepKit service. I hadn’t really the time to do so but I’m sure it’s awsome,  and it even work on Macs. So if you want to prepare for an exam, you might consider them.

I’m very thankful for them for teaching me to never promise anything I’m not really commited to do.

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Annual Blogging Report 2011

Posted by Jakub Holý on January 1, 2012

The stats helper monkeys prepared a 2011 annual report for this blog.

Here’s an excerpt:

Madison Square Garden can seat 20,000 people for a concert. This blog was viewed about 62 000 times in 2011. If it were a concert at Madison Square Garden, it would take about 3 sold-out performances for that many people to see it.

Click here to see the complete report.

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