DDevelopment & Design

OSGi Blueprint visualization

What is blueprint?Blueprint is a dependency injection framework for OSGi bundles. It could be written by hand or generated using Blueprint Maven Plugin. Blueprint file is only an XML describing beans, services and references. Each OSGi bundle could hav…

What is blueprint?

Blueprint is a dependency injection framework for OSGi bundles. It could be written by hand or generated using Blueprint Maven Plugin. Blueprint file is only an XML describing beans, services and references. Each OSGi bundle could have one or more blueprint files.

Blueprint files represent architecture of our bundle. Let’s visualize it using groovy script and graphviz available in my github repository and analyze.

Example generation

Pre: All you need is groovy and graphviz installed on your OS

I am working mostly with bundles with generated blueprint, so I will use blueprint file generated from Blueprint Maven Plugin tests as example. All examples are included in github repository.

Generation could be invoked by running run.sh script with given destination file prefix (png extension will be added to it) and path to blueprint file:

mkdir -p target

./run.sh target/fullBlueprint fullBlueprint.xml

Visualization is available here.

Separating domains

First if you look at the image, you see that some beans are grouped. You could easily extract such domains with tree roots: beanWithConfigurationProperties and beanWithCallbackMethods to separate blueprint files and bundles in future and generate images from them:

./run.sh target/beanWithCallbackMethods example/firstCut/beanWithCallbackMethods.xml
./run.sh target/beanWithConfigurationProperties example/firstCut/beanWithConfigurationProperties.xml
./run.sh target/otherStuff example/firstCut/otherStuff.xml

Now we have three, a bit cleaner, images: beanWithConfigurationProperties.png, beanWithCallbackMethods.png and otherStuff.png.

We also could generate image from more than one blueprint:

./run.sh target/joinFirstCut example/firstCut/otherStuff.xml example/firstCut/beanWithConfigurationProperties.xml example/firstCut/beanWithCallbackMethods.xml

And the result is here. The image contains beans grouped by file, but if you do not like it, you could force generation without such separation using option --no-group-by-file:

./run.sh target/joinFirstCutGrouped example/firstCut/otherStuff.xml example/firstCut/beanWithConfigurationProperties.xml example/firstCut/beanWithCallbackMethods.xml --no-group-by-file

It will generate image with all beans from all files.

Exclusion

Sometimes it is difficult to spot and extract other domains. It will be easier to do some experiments on blueprint. For example, bean my1 is a dependency for too many other beans. You could consider converting my1 bean to OSGi service and extracting it to another bundle.

Let’s exclude my1 bean from generation via -e option and see what happens:

./run.sh target/otherStuffWithoutMy example/firstCut/otherStuff.xml -e my1

Result is available here. Now we see, that tree with root bean myFactoryBeanAsService could be separated and my1 could be inject to it as osgi service in another bundle.

You could exclude more than one bean adding -e switch for each of them, e. g. -e my1 -e m2 -e myBean123.

Conclusion

Blueprint is great for dependency injection for OSGi bundles, but it is easy to create quite big context containing many domains. It is much easier to recognize or search for such domains using blueprint visualizer script.

 

YOUR CODE HRER

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DDevelopment & Design

Thought static method can’t be easy to mock, stub nor track? Wrong!

No matter why, no matter is it a good idea. Sometimes one just wants to check or it's necessary to be done. Mock a static method, woot? Impossibru!

In pure Java world it is still a struggle. But Groovy allows you to do that really simple. Well, not groovy alone, but with a great support of Spock.

Lets move on straight to the example. To catch some context we have an abstract for the example needs. A marketing project with a set of offers. One to many.

import spock.lang.Specification

class OfferFacadeSpec extends Specification {

    OfferFacade facade = new OfferFacade()

    def setup() {
        GroovyMock(Project, global: true)
    }

    def 'delegates an add offer call to the domain with proper params'() {
        given:
            Map params = [projId: projectId, name: offerName]

        when:
            Offer returnedOffer = facade.add(params)

        then:
            1 * Project.addOffer(projectId, _) >> { projId, offer -> offer }
            returnedOffer.name == params.name

        where:
            projectId | offerName
            1         | 'an Offer'
            15        | 'whasup!?'
            123       | 'doskonała oferta - kup teraz!'
    }
}
So we test a facade responsible for handling "add offer to the project" call triggered  somewhere in a GUI.
We want to ensure that static method Project.addOffer(long, Offer) will receive correct params when java.util.Map with user form input comes to the facade.add(params).
This is unit test, so how Project.addOffer() works is out of scope. Thus we want to stub it.

The most important is a GroovyMock(Project, global: true) statement.
What it does is modifing Project class to behave like a Spock's mock. 
GroovyMock() itself is a method inherited from Specification.  The global flag is necessary to enable mocking static methods.
However when one comes to the need of mocking static method, author of Spock Framework advice to consider redesigning of implementation. It's not a bad advice, I must say.

Another important thing are assertions at then: block. First one checks an interaction, if the Project.addOffer() method was called exactly once, with a 1st argument equal to the projectId and some other param (we don't have an object instance yet to assert anything about it).
Right shit operator leads us to the stub which replaces original method implementation by such statement.
As a good stub it does nothing. The original method definition has return type Offer. The stub needs to do the same. So an offer passed as the 2nd argument is just returned.
Thanks to this we can assert about name property if it's equal with the value from params. If no return was designed the name could be checked inside the stub Closure, prefixed with an assert keyword.

Worth of  mentioning is that if you want to track interactions of original static method implementation without replacing it, then you should try using GroovySpy instead of GroovyMock.

Unfortunately static methods declared at Java object can't be treated in such ways. Though regular mocks and whole goodness of Spock can be used to test pure Java code, which is awesome anyway :)No matter why, no matter is it a good idea. Sometimes one just wants to check or it's necessary to be done. Mock a static method, woot? Impossibru!

In pure Java world it is still a struggle. But Groovy allows you to do that really simple. Well, not groovy alone, but with a great support of Spock.

Lets move on straight to the example. To catch some context we have an abstract for the example needs. A marketing project with a set of offers. One to many.

import spock.lang.Specification

class OfferFacadeSpec extends Specification {

    OfferFacade facade = new OfferFacade()

    def setup() {
        GroovyMock(Project, global: true)
    }

    def 'delegates an add offer call to the domain with proper params'() {
        given:
            Map params = [projId: projectId, name: offerName]

        when:
            Offer returnedOffer = facade.add(params)

        then:
            1 * Project.addOffer(projectId, _) >> { projId, offer -> offer }
            returnedOffer.name == params.name

        where:
            projectId | offerName
            1         | 'an Offer'
            15        | 'whasup!?'
            123       | 'doskonała oferta - kup teraz!'
    }
}
So we test a facade responsible for handling "add offer to the project" call triggered  somewhere in a GUI.
We want to ensure that static method Project.addOffer(long, Offer) will receive correct params when java.util.Map with user form input comes to the facade.add(params).
This is unit test, so how Project.addOffer() works is out of scope. Thus we want to stub it.

The most important is a GroovyMock(Project, global: true) statement.
What it does is modifing Project class to behave like a Spock's mock. 
GroovyMock() itself is a method inherited from Specification.  The global flag is necessary to enable mocking static methods.
However when one comes to the need of mocking static method, author of Spock Framework advice to consider redesigning of implementation. It's not a bad advice, I must say.

Another important thing are assertions at then: block. First one checks an interaction, if the Project.addOffer() method was called exactly once, with a 1st argument equal to the projectId and some other param (we don't have an object instance yet to assert anything about it).
Right shit operator leads us to the stub which replaces original method implementation by such statement.
As a good stub it does nothing. The original method definition has return type Offer. The stub needs to do the same. So an offer passed as the 2nd argument is just returned.
Thanks to this we can assert about name property if it's equal with the value from params. If no return was designed the name could be checked inside the stub Closure, prefixed with an assert keyword.

Worth of  mentioning is that if you want to track interactions of original static method implementation without replacing it, then you should try using GroovySpy instead of GroovyMock.

Unfortunately static methods declared at Java object can't be treated in such ways. Though regular mocks and whole goodness of Spock can be used to test pure Java code, which is awesome anyway :)