As many of you know, JAX-RS 2 is one of the most important parts of Java EE 7. One key enhancement in JAX-RS 2 that doesn't seem to get much attention is it's integration with Bean Validation 1.1 (specifically method validation). The key significance of the enhancement is that it allows for highly declarative data validation for edge client interfaces (in fact the method validation feature introduced in Bean Validation 1.1 is valuable for WebSocket or local/EJB services for this same reason). Bhakti Mehta explains JAX-RS 2 and Bean Validation 1.1 integration well inthis blog post. In addition to covering JAX-RS 2, she also discusses how Bean Validation can be used with JAX-RS 1.1. You should also check out the following excellent video by celebrated Java champion Adam Bean showing JAX-RS 2 and Bean Validation 1.1 in action using live coding with NetBeans and GlassFish:

The documentation for Jersey, the JAX-RS 2 reference implementation included in GlassFish and WebLogic, also has anexcellent section on the new feature.