Introduction

Here is an example. Read on for the break down.

<?xml version="1.0"?>

<architecture>

    <configuration>

        <sources no-packages="ignore">
            <source not-found="ignore">core\target\classes</source>
            <source not-found="ignore">util\target\classes</source>
            <source not-found="ignore">parent-pom\target\classes</source>
            <source not-found="ignore">web\target\classes</source>
        </sources>

        <cyclicalDependency test="true"/>

    </configuration>


    <rules>

        <rule id="dao">

            <comment>
                The dao interface package should rely on nothing.
            </comment>

            <packages>
                <package>
                    com.seventytwomiles.pagerank.core.dao
                </package>
                <package>
                    com.seventytwomiles.pagerank.core.dao.hibernate
                </package>
            </packages>

            <violations>
                <violation>
                    com.seventytwomiles.pagerank.core.services
                </violation>
                <violation>
                    com.seventytwomiles.pagerank.core.builder
                </violation>
                <violation>
                    com.seventytwomiles.pagerank.util
                </violation>
            </violations>
        </rule>

        <rule id="strategy">

            <comment>
                Strategies should be as pluggable as possible
            </comment>

            <packages>
                <package>
                    com.seventytwomiles.pagerank.serviceproviders.startegies
                </package>
            </packages>


            <violations>
                <violation>
                    com.seventytwomiles.pagerank.core.services
                </violation>
                <violation>
                    com.seventytwomiles.pagerank.core.dao.hibernate
                </violation>
            </violations>
        </rule>

        <rule id="model">

            <comment>
                Model should remain competely isolated
            </comment>

            <packages>
                <package>
                    com.seventytwomiles.pagerank.core.model
                </package>
            </packages>

            <violations>
                <violation>
                    com.seventytwomiles.pagerank.core.dao
                </violation>
                <violation>
                    com.seventytwomiles.pagerank.core.dao.hibernate
                </violation>
                <violation>
                    com.seventytwomiles.pagerank.core.services
                </violation>
                <violation>
                    com.seventytwomiles.pagerank.core.strategy
                </violation>
                <violation>
                    com.seventytwomiles.pagerank.core.builder
                </violation>
                <violation>
                    com.seventytwomiles.pagerank.util
                </violation>
            </violations>
        </rule>

    </rules>

</architecture>

Breakdown

Configuration

Sources

<sources no-packages="ignore">
    <source not-found="ignore">core\target\classes</source>
    <source not-found="ignore">util\target\classes</source>
    <source not-found="ignore">parent-pom\target\classes</source>
    <source not-found="ignore">web\target\classes</source>
</sources>

Sources are the directories that JDepend will analyze. The Jdepend docs call these sources, but in reality you want to point to your complied classes.

<sources no-packages="ignore">

Valid no-packages values are ignore and exception.

• ignore will continue on when the source directory does not exist
• exception will throw a SourceNotFoundException when the directory does not exit.

<source not-found="ignore">core/target/classes</source>

Sources can be a relative path or an absolute path. Valid not-found values are ignore and exception.

• ignore will continue when no packages exist, but nothing will be tested. Not recommended.
• exception will throw a RuntimeException: No packages found when no packages are found in the given sources.

Cyclic Dependency Test

<cyclicalDependency test="true"/>

Easy as true or false to indicate weather you want this test to run or not. When this test runs and fails, a CyclicRedundencyException is thrown.

Rules

Rules define a package, and then go on to list each package that would be considered a violation to depend on. An id is used to refer to the rule when something goes wrong, and a comment may be entered in order to document the rule for future developers (or even for yourself for that matter)

<rule id="dao">

    <comment>
        The dao interface package should rely on nothing.
    </comment>

    <packages>
        <package>
            com.seventytwomiles.pagerank.core.dao
        </package>
        <package>
            com.seventytwomiles.pagerank.core.dao.hibernate
        </package>
    </packages>

    <violations>
        <violation>
            com.seventytwomiles.pagerank.core.services
        </violation>
        <violation>
            com.seventytwomiles.pagerank.core.builder
        </violation>
        <violation>
            com.seventytwomiles.pagerank.util
        </violation>
    </violations>
</rule>

ids can not be duplicated, but packages can. If you want to break up violations for the same package you can do that.

You can add more than one package to a rule. For example ..dao and ..dao.hibernate packages are probably going to be the same, so you can define them in a single rule. This is a change from the version 1 releases

You can not add a violation that is identical to the package. This is because, in reality, if you have a class that uses a class in the same package, no imports are defined, and therefor this situation can not be tested. If you try this, you will get an IllegalRuleException

Conclusion

Thats all there is to it. You can define as many rules as you would like, and cyclicalDependency is not required at all.