Could it be that this was an intermittent failure? If I try to click the link you provided, I can successfully download the pom file:
https://repository.jboss.org/nexus/content/groups/public//org/drools/drools-api/5.2.0-alpha1/drools-api-5.2.0-alpha1.pom
Does this work for you?
And if you retry now, do you still have the same problem?
If you run the maven build successfully, it should download all the dependencies.
You can run mvn eclipse:eclipse to generate eclipse project files for all the different modules. That should allow you to simply import these projects into Eclipse and they should all compile without errors then (as long as you set the M2_REPO classpath variable to your maven repository folder).
Kris