EXHIBIT 2
JOINT FILING AGREEMENT
The undersigned hereby agree to the joint filing of the Schedule 13D to which this Agreement is attached.
Dated: March 9, 2012
| DISCOVERY GROUP I, LLC | |||
| for itself and as general partner of | |||
| DISCOVERY EQUITY PARTNERS, L.P. | |||
| By | Michael R. Murphy* | ||
| Michael R. Murphy | |||
| Managing Member | |||
| Daniel J. Donoghue* | |||
| Daniel J. Donoghue | |||
| Michael R. Murphy* | |||
| Michael R. Murphy | |||
| *By: | /s/ Mark Buckley | ||
| Mark Buckley | |||
| Attorney-in-Fact for Daniel J. Donoghue | |||
| Attorney-in-Fact for Michael R. Murphy | |||