  We review the solution of the boundary CFTs that describe the symmetric
branes in the Nappi-Witten gravitational wave, namely D2 and S1 branes. The D2
branes are the twisted branes of the model while the S1 branes are the Cardy
branes. We present in both cases the bulk-boundary couplings and the boundary
three-point couplings and discuss the relation with branes in AdS3 and in S3.
We also discuss the analogy between the open string couplings in the H4 model
and the couplings for magnetized and intersecting branes.
