Throughout this book, you will notice references to properties which
can be used in a POM file. Sibling dependencies in a
multi-project build can be referenced using the
${project.groupId} and
${project.version} properties and any part of the
POM can be referenced by prefixing the variable name
with "project.". Environment variables and Java System properties can be
referenced, as well as values from your
~/.m2/settings.xml file. What you haven't seen yet is
an enumeration of the possible property values and some discussion about
how they can be used to help you create portable builds. This chapter
provides such an enumeration.
If you've been using property references in your
POM, you should also know that Maven has a feature
called Resource Filtering which allows you to replace property references
in any resource files stored under
src/main/resources. By default this feature is
disabled to prevent accidental replacement of property references. This
feature can be used to target builds toward a specific platform and to
externalize important build variables to properties files,
POMs, or profiles. This chapter introduces the resource
filtering feature and provides a brief discussion of how it can be used to
create portable enterprise builds.
