Within Apache Tomcat, a realm is (cite) a "database" of usernames and passwords that identify valid users of a web application (or set of web applications), plus an enumeration of the list of roles associated with each valid user. Learn more about them in the Realm Configuration HOW-TO from the Tomcat website.
In order to use Apache Directory Server (ApacheDS) as a realm, the straight forward approach is to use the JNDIRealm shipped with Tomcat. It can handle arbitrary LDAP servers, among them ApacheDS.
Because ApacheDS is 100% pure Java and embeddable, there is another option: Implement the Realm interface from Apache Tomcat and run within Tomcat. There are (at least) two interesting things about this approach:
While the first point promises some performance advantages, which are irrelevant in most situations (because LDAP servers like ApacheDS are optimized for read operations anyway), the second reason makes this approach a good option for development environments.
The current implementation of the realm has started as a proof of concept, but already works quite well. You can find the sources here:
It is not an official artifact of Apache Directory yet. Although if some people are interested, it soon can be. In the meantime, there are no official releases etc.
After checking out the sources from subversion,
builds a jar file which contains the Realm class. In order to use it, one has to copy it to the Tomcat server lib directory, along with the required ApacheDS and dependency jars.
Activation in Tomcat server.xml is simply
<Realm className="org.apache.directory.tomcatrealm.EmbeddedApacheDsRealm" />
within the context the realm is intended to act.
When Tomcat starts up, ApacheDS starts as well and opens an LDAP port which defaults to 10389. You can use any LDAP client to connect to the embedded ApacheDS. We recommend Apache Directory Studio for this tasks.
Within the realm definition in Tomcats server.xml, you can add some attributes to configure ApacheDS:
<Realm className="org.apache.directory.tomcatrealm.EmbeddedApacheDsRealm" ldapPort="389" userSearchBase="ou=users,ou=system" groupSearchBase="ou=users,ou=system" />
Feel free to check it out and provide feedback. Further discussions about whether we provide this as official artifact will be on the dev-list of Apache Directory project.