DDevelopment & Design

Geecon 2011 – day 2

And now for part 2 of my visit to Geecon 2011!

1. Jim Webber “Revisiting SOA for the 21st century”

Now this was awesome! Jim Webber, a former ThoughtWorks employee, now Neo4j evangelist (in Neotechnology) described his views on how SOA should look – according to him. This was presented previously, on other occasions as his “Guerilla SOA” talk – generally he advocated for REST based services, loose contracts (stating that WSDLs are too verbose and code generation is evil).

Jim mentioned Martin Fowler’s article on integration databases but I couldn’t find it anywhere – thou the topic looks interesting. He also recommended BDD and exposing tests on the web for the end user to use them as early as possible.

One big point he made his case with was not relying on enterprise software. Simple tools can do much better job. He compared implementing Web Services security (Secured SOAP over HTTP over TCP IP) to REST based service accessed through HTTPS – basic and easily testable with tools like curl.

Great talk. One of the best!

2. Staffan Noteberg “Regex – the future programming”

I must confess, that this did not go too well. The whole talk was well prepared and laid out but it lacked depth. It was pretty basic introduction to regex. From the presentation’s subject I was rather prepared for some novel uses of regex – like for example: showing how to filter big volume of data with simple regex or sth.

But the talk was fun, Staffan is a good speaker. He is also an author of pomodoro technique book – I intend to read sth abut this technique and this may be a nice start

3. Bartosz Kowalewski “Is OSGI ready for wide adoption?”

If it comes to titles I tend to rely on them pretty heavily, however strange it may seem. This time I also did – and the whole talk did not give me a definitive answer to the stated question.

Sure, the presentation was informative, but it described some OSGI specific, quite low level stuff. Of course, if you want to use OSGI – even by leveraging application server with OSGI under the hood – you should know a fair bit about the technology itself. Even thou the AS does a good job of hiding OSGI container specifics from the developer, in case of problems it’s better to be well informed. All in all – the talk gave too little information for me.

4. Vaclav Pech “Pick low hanging fruit”

“Parallelism is not hard, multithreading is” – this was the key sentence of the presentation. The speaker showed how to introduce concurrency into normal java/groovy code by sprinkling it with concurrency powder. Easy enough! With GPars library he showed:

  • running processing tasks with thread pools
  • testing concurrent code
  • Fork/join Thread Pool – multiple thread queues (note to self: fork/join is good for hierarchical problems)
  • low-hanging fruits:
    • async calculations
    • fork/join
    • dataflow
    • parallel collection processing
  • Actors are great – use GPars or Akka, is sufficient to use @ActiveMethod and @ActiveObject annotations and Actors are usable in OO-world

Good talk, well received!

5. Anton Arhipov “Bytecode for discriminating developers”

Technical introduction to the world of bytecode, jvm specification details. I’ve drifted away to some other topics – really – can’t recall what this was all about.

6. Andreas Almiray “Polyglot Programming”

This was a nice talk covering Groovy, Scala and Closure. The whole point of it was to show how cool it is to play with emerging JVM languages. They are not only fun but also useful. What’s more, they bring freshness to java world, injecting it with some new paradigms and methodologies. It is easier to incorporate new ideas into younger JVM languages than to the mature Java.

7. Jim Webber “A pragmatic introduction to Neo4j”

And Jim Webber again, this time with some Neo4j evangelism. First came some taxonomy information on NoSQL databases (Not Only SQL) as a whole – than some specific examples of problems solvable with graph databases – and Neo4j is a graph database.

Main points of Jim’s talk were:

  • sharding a database is important for scalability
  • series data – should be OK to use Neo4j as their storage

Conclusion

These were all the sessions I attended. On Saturday there was a Hacker-garden, but neither I had time nor will to stay – the topics were very interesting and I’d definitely like to experience such an event, but after 2 days of continuous talks I was rather tired.

To sum up, 2011’s Geecon was a great experience, with lots of interesting talks and lots of new inspirations. Keep up the good work guys!

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DDevelopment & Design

Spock, Java and Maven

Few months ago I've came across Groovy - powerful language for JVM platform which combines the power of Java with abilities typical for scripting languages (dynamic typing, metaprogramming).

Together with Groovy I've discovered spock framework (https://code.google.com/p/spock/) - specification framework for Groovy (of course you can test Java classes too!). But spock is not only test/specification framework - it also contains powerful mocking tools.

Even though spock is dedicated for Groovy there is no problem with using it for Java classes tests. In this post I'm going to describe how to configure Maven project to build and run spock specifications together with traditional JUnit tests.


Firstly, we need to prepare pom.xml and add necessary dependencies and plugins.

Two obligatory libraries are:
<dependency>
    <groupid>org.spockframework</groupId>
    <artifactid>spock-core</artifactId>
    <version>0.7-groovy-2.0</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupid>org.codehaus.groovy</groupId>
    <artifactid>groovy-all</artifactId>
    <version>${groovy.version}</version>
    <scope>test</scope>
</dependency>
Where groovy.version is property defined in pom.xml for more convenient use and easy version change, just like this: 
<properties>
    <gmaven-plugin.version>1.4</gmaven-plugin.version>
    <groovy.version>2.1.5</groovy.version>
</properties>

I've added property for gmaven-plugin version for the same reason ;)

Besides these two dependencies, we can use few additional ones providing extra functionality:
  • cglib - for class mocking
  • objenesis - enables mocking classes without default constructor
To add them to the project put these lines in <dependencies> section of pom.xml:
<dependency>
    <groupid>cglib</groupId>
    <artifactid>cglib-nodep</artifactId>
    <version>3.0</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupid>org.objenesis</groupId>
    <artifactid>objenesis</artifactId>
    <version>1.3</version>
    <scope>test</scope>
</dependency>

And that's all for dependencies section. Now we will focus on plugins necessary to compile Groovy classes. We need to add gmaven-plugin with gmaven-runtime-2.0 dependency in plugins section:
<plugin>
    <groupid>org.codehaus.gmaven</groupId>
    <artifactid>gmaven-plugin</artifactId>
    <version>${gmaven-plugin.version}</version>
    <configuration>
        <providerselection>2.0</providerSelection>
    </configuration>
    <executions>
        <execution>
            <goals>
                <goal>compile</goal>
                <goal>testCompile</goal>
            </goals>
        </execution>
    </executions>
    <dependencies>
        <dependency>
            <groupid>org.codehaus.gmaven.runtime</groupId>
            <artifactid>gmaven-runtime-2.0</artifactId>
            <version>${gmaven-plugin.version}</version>
            <exclusions>
                <exclusion>
                    <groupid>org.codehaus.groovy</groupId>
                    <artifactid>groovy-all</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupid>org.codehaus.groovy</groupId>
            <artifactid>groovy-all</artifactId>
            <version>${groovy.version}</version>
        </dependency>
    </dependencies>
</plugin>

With these configuration we can use spock and write our first specifications. But there is one issue: default settings for maven-surefire plugin demand that test classes must end with "..Test" postfix, which is ok when we want to use such naming scheme for our spock tests. But if we want to name them like CommentSpec.groovy or whatever with "..Spec" ending (what in my opinion is much more readable) we need to make little change in surefire plugin configuration:
<plugin>
    <groupid>org.apache.maven.plugins</groupId>
    <artifactid>maven-surefire-plugin</artifactId>
    <version>2.15</version>
    <configuration>
        <includes>
            <include>**/*Test.java</include>
            <include>**/*Spec.java</include>
        </includes>
    </configuration>
</plugin>

As you can see there is a little trick ;) We add include directive for standard Java JUnit test ending with "..Test" postfix, but there is also an entry for spock test ending with "..Spec". And there is a trick: we must write "**/*Spec.java", not "**/*Spec.groovy", otherwise Maven will not run spock tests (which is strange and I've spent some time to figure out why Maven can't run my specs).

Little update: instead of "*.java" postfix for both types of tests we can write "*.class" what is in my opinion more readable and clean:
<include>**/*Test.class</include>
<include>**/*Spec.class</include>
(thanks to Tomek Pęksa for pointing this out!)

With such configuration, we can write either traditional JUnit test and put them in src/test/java directory or groovy spock specifications and place them in src/test/groovy. And both will work together just fine :) In one of my next posts I'll write something about using spock and its mocking abilities in practice, so stay in tune.