in that case, he is really wierd,
vignesh Thamarai, please explain what have you understood so far in this program,
I am afraid i have not heard of classes such as PDU, PDUv1, BERInputStream, BER,etc.
If you quote your sources maybe we could help.
all i can say is that this represents a messaging service that reads from some kind of stream (using some kind of encoding, decoding)