Why is DITP a stream oriented protocol ?

 ... because it reduces communication latency and memory requirement.

Communication latency:
In a message oriented protocol the sender has to fully encode the message before it can be sent, and the receiver must receive the whole message before he can start decoding and processing it. The receiver has thus to wait for the whole message to be generated, sent and received before doing anything.

With a stream oriented protocol the communication process is pipelined. The sender encodes and sends a first chunk of the message allowing the receiver to start decoding and processing it, while the sender encodes and sends the next chunk of the message. The sender and the receiver then work in parallel and not in sequence.

Manual data split is possible with message oriented protocol but at the price of a significant complexity increase of user code, and such splitting can become very tricky when dealing with object aggregates.

Memory requirement:
A message oriented protocol requires that the sender and the receiver hold an encoded copy of the full message. This puts the memory management system under stress because these memory blocks have a short life span, they are of varying size and they are sometime big.

With a stream oriented protocol, the memory requirement is limited to the storage of the encoded message chunk, and this even if the message size is huge. The buffer holding a message chunk can also be easily recycled because it is of a fixed size.


DITP has thus been designed to be a stream oriented protocol, while most inter-object communication protocols are classically message oriented (i.e. CORBA, RMI, ICE). SOAP is the only inter-object communication protocol I know that is stream oriented. It thus benefits from the reduced latency and small memory requirement; but these benefits are spoilt by the ASCII and xml encoding.