Dmitriy,
Although having invoke() was really important for us, implementing invoke() does not look trivial (need to think about real multi-lingual and cross-platform design) and we do not have time to implement it on the first phase. Currently thin client protocol does not support it so we would have to design it ourselves. Still we will need invoke and transactions on the next phases and really appreciate if community would design something to support it in the binary protocol.
