DDevelopment & Design

Tired of exporting your OSGI metatype to client manually?

Feel my pain

We use OSGi, but we don’t deploy our bundles further than testing environment. It is our client who deploys it to production. However, they rarely read the metatypes – as metatype files are hidden deep inside jars and their format is not very user-friendly (who wants to read XMLs?). This is why they don’t know how to configure the application.

Sharing metatypes

If you work with OSGi metatype files, you have to find some way of informing your client what configuration is necessary for your application. There are a few ways of sharing this information:

  • You can send configuration options by e-mail or Jira/Redmine/(paste your issue tracker here). However, this might cause a big mess, searching is horrible, and it becomes outdated faster than you can say I hate sending metatypes.
  • You can share your repository with the client so that they always have up-to-date XMLs. Nevertheless, XML files are difficult to read and are scattered across whole modules.
  • You can keep your configuration in some document (e.g. Markdown), providing easy access for the client, but you must remember to synchronize it every time you change metatype.

metatype-exporter-maven-plugin to the rescue!

Our new Maven plugin allows us to automatically generate Markdown file from metatype files. Just add the plugin and enjoy automatically generated configuration created without any effort. Sample configuration may look like below.

<project ...>

    ...

    <pluginRepositories>
        <pluginRepository>
            <id>touk</id>
            <url>https://philanthropist.touk.pl/nexus/content/repositories/releases</url>
            <!-- we are not on central, but we are going to be there soon -->
        </pluginRepository>
    </pluginRepositories>
    <build>
        <plugins>
            <plugin>
                <groupId>pl.touk.osgi</groupId>
                <artifactId>metatype-exporter-maven-plugin</artifactId>
                <version>@metatype-exporter-maven-plugin.version@</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>export</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <destination>${project.build.directory}/classes/documentation</destination>
                    <outputFileName>ConfigurationDescription.md</outputFileName>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

 

Markdown produced by this configuration may look like this:

# Properties name (theseAreProperties) for pid this.is.first.pid

Description goes here

| ID  | Name  | Required | Type    | Default value | Options                         | Description |
| --- | ----- | -------- | ------- | ------------- | ------------------------------- | ----------- |
| id1 | name1 | Yes      | String  |               |                                 | desc1       |
| id2 |       | No       | Long    | 123           |                                 | desc2       |
| id3 |       | Yes      | Integer |               | <ul><li>15</li><li>30</li></ul> |             |

# Properties name (secondProps) for pid this.is.second.pid

| ID  | Required | Type   |
| --- | -------- | ------ |
| id1 | Yes      | String |

Markdown files are great because many git repositories like Gitlab or Github render Markdown files nicely. You can view the above file here: https://gist.github.com/piotrekfus91/ba36404341664c48df19576350a2340f.

Definitely more readable, huh?

Change language if your client doesn’t speak English

If you want to change the language of generated files, just add a resource bundle named MarkdownBundle, change locale in plugin configuration and enjoy your custom language. English and Polish are available out of the box.

<project ...>

    ...

    <build>
        <plugins>
            <plugin>
                <groupId>pl.touk.osgi</groupId>
                <artifactId>metatype-exporter-maven-plugin</artifactId>
                <version>@metatype-exporter-maven-plugin.version@</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>export</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <language>de</language>
                    <country>DE</country>
                </configuration>
                <depenedencies>
                    <dependency>
                        <!-- maven coordinates of the jar with resource bundle -->
                    </dependency>
                <depenedencies>
            </plugin>
        </plugins>
    </build>
</project>

Resource bundle (for example MarkdownBundle_de.properties)

forPid=...
attributeHeaderId=...
attributeHeaderName=...
attributeHeaderDescription=...
attributeHeaderOptions=...
attributeHeaderType=...
attributeHeaderDefaultValue=...
attributeHeaderRequired=...
attributeRequiredTrue=...
attributeRequiredFalse=...

Summary

Our problem – client doesn’t know how to configure the application – was solved with our new Maven plugin. The sources may be found on https://github.com/TouK/metatype-exporter-maven-plugin.

What’s next?

We are planning to add other output formats or enable users to provide custom templates. If you have any suggestions for enhancements or found a bug, just let us know in a Github issue.

— Previous article

Using Kotlin extensions in Groovy

Next article —

Gerrit notifications via Rocket.Chat

You May Also Like
DDevelopment & Design

JCE keystore and untrusted sites

Recently at work I was in need of connecting to a web service exposed via HTTPS. I've been doing this from inside Servicemix 3.3.1, which may seem a bit inhibiting, but that was a requirement. Nevertheless I've been trying my luck with the included ser...Recently at work I was in need of connecting to a web service exposed via HTTPS. I've been doing this from inside Servicemix 3.3.1, which may seem a bit inhibiting, but that was a requirement. Nevertheless I've been trying my luck with the included ser...
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 :)