IoC stands for inversion of control. There are several implementations for this like:
 * Spring
 * Seam
 * and lots of others

Spring probably the most used one. Seam is coming up. Spring is chosen because it has a good track record and the team knows it. 

For the persistence layer, two types of configuration styles can be used
 * jpa style (at this moment not possible to use Hibernate search)
 * hibernate style  (possible to use Hibernate Search)
For the reasons mentioned the Spring configuration in Hibernate style is chosen.