This plugin uses the Graphviz library to render .dot files into images.
The most basic usage of the plugin is to simply wire it into your POM and run the dot goal:
<plugins>
<plugin>
<groupId>us.bryon</groupId>
<artifactId>graphviz-maven-plugin</artifactId>
<version>1.0</version>
<executions>
<execution>
<goals>
<goal>dot</goal>
</goals>
</execution>
</executions>
</plugin>
...
</plugins>
If you put a .dot file into src/main/dot (let's say, src/main/dot/foo.dot):
graph { foo--bar }
It will turn that into target/graphviz/foo.png:

The dotml goal is very similar - the only difference is that it expects src/main/dotml to contain XML files in the DOTML format.
For all the features and options, read the documents for the graphviz:dot and graphviz:dotml mojos.
graphviz-maven-plugin is licensed under the New BSD License.
This product includes DOTML developed by Martin Loetzsch (http://www.martin-loetzsch.de/DOTML). Use of DOTML is governed by this license.