Software Developer and Architect

2 minute read

First steps: failure for multi module maven project

Following the tutorial here for maven projects. This suggests the following:

<plugin>
    <groupId>com.buschmais.jqassistant</groupId>
    <artifactId>jqassistant-maven-plugin</artifactId>
    <version>1.9.0</version>
    <executions>
        <execution>
            <goals>
                <goal>scan</goal>
                <goal>analyze</goal>
            </goals>
            <configuration>
                <warnOnSeverity>MINOR</warnOnSeverity>
                <failOnSeverity>MAJOR</failOnSeverity>
            </configuration>
        </execution>
    </executions>
</plugin>

This works well for a single module maven projects. Since I used it on a multi module project, you will face problems. JQAssistant tries to hold the running Neo4J database open, to access it more performantly. This seems to have some problems in my situation.

Success for multi module maven project

Note: If there are extensions to the module reactor ( annotation processors and stuff ), there are problems holding open the Neu4j database.

The solution is to configure jqassistant to close and open the database for each module by configuring storeLifecycle to MODULE.

<plugin>
    <groupId>com.buschmais.jqassistant</groupId>
    <artifactId>jqassistant-maven-plugin</artifactId>
    <version>1.9.0</version>
    <configuration>
        <storeLifecycle>MODULE</storeLifecycle>
    </configuration>
    <executions>
        <execution>
            <goals>
                <goal>scan</goal>
                <goal>analyze</goal>
            </goals>
            <configuration>
                <warnOnSeverity>MINOR</warnOnSeverity>
                <failOnSeverity>MAJOR</failOnSeverity>
            </configuration>
        </execution>
    </executions>
</plugin>

Maven profile

I configure all that stuff into a maven profile, to keep it all together. Since there is no magic in this here the profile without any comment and plugins configured.

<profile>
    <id>process-jqassistant</id>
    <build>
        <plugins>
            <plugin>
                <groupId>com.buschmais.jqassistant</groupId>
                <artifactId>jqassistant-maven-plugin</artifactId>
                <version>1.9.0</version>
                ...
            </plugin>
        </plugins>
    </build>
</profile>

Start the server

After your local Neo4j database is generated you can start a local server with jqassistant:server to start a Neo4j server. The Neo4j browser can be started via http://localhost:7474.

first simple Cypher queries

To request a single class you match its name within the pattern.

MATCH (my:Java:Class {name:'MyClass'})
RETURN my

or filter it in the where clause.

MATCH (my:Java:Class)
WHERE my.name='MyClass'
RETURN my

But be sure what you are doning. The latter could result in a complete node list scan.

Now we want to return its children as well. The optional match seems to be something like a left join in SQL.

MATCH (my:Java:Class {name:'MyClass'})
OPTIONAL MATCH (p:Java)<-[:DEPENDS_ON]-(my)
RETURN my, p

Reseting styling

When you have a bunch of colors assigned to labels, you will find, that you cannot unset a color for a label. Using the following as a query, you can reset all the styling.

:style reset

Dashboard is a very good start

Using the standard dashboard you are getting some basic values from your fresh generated Neo4j database. By the way you started this using: http://localhost:7474/jqassistant/dashboard.

<plugin>
    <groupId>com.buschmais.jqassistant</groupId>
    <artifactId>jqassistant-maven-plugin</artifactId>
    <version>1.9.0</version>
    <configuration>
        <storeLifecycle>MODULE</storeLifecycle>
        <scanIncludes>
            <scanInclude>
                <path>${project.basedir}/.git</path>
            </scanInclude>
        </scanIncludes>
        <groups>
            <group>jqassistant-dashboard:Default</group>
            <!-- Insert your own group references here -->
        </groups>
    </configuration>
    <executions>
        <execution>
            <goals>
                <goal>scan</goal>
                <goal>analyze</goal>
            </goals>
            <configuration>
                <warnOnSeverity>MINOR</warnOnSeverity>
                <failOnSeverity>MAJOR</failOnSeverity>
            </configuration>
        </execution>
    </executions>
    <dependencies>
        <dependency>
            <groupId>de.kontext-e.jqassistant.plugin</groupId>
            <artifactId>jqassistant.plugin.git</artifactId>
            <version>1.8.0</version>
        </dependency>
        <dependency>
            <groupId>org.jqassistant.contrib.plugin</groupId>
            <artifactId>jqassistant-dashboard-plugin</artifactId>
            <version>1.9.0</version>
        </dependency>
    </dependencies>
</plugin>

virtual nodes and relations

https://neo4j.com/labs/apoc/4.1/virtual/

Some commands create nodes and relationships but you only want to display this stuff. Thats for you.

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