In addition to the FAQ below, see also the EMF Validation Framework Developer Guide documentation included in the EMF Validation SDK.
Newbie / General
Does EMF Validation 1.x work with J2SE 1.4?
Yes and no. The core EMF Validation framework works with EMF 2.2 or higher and J2SE 1.4.
However, if you need the OCL extensions in the org.eclipse.emf.validation.ocl plug-in, the requirements are different.