The hard problems in distributed computing

The hard problems in distributed computing are not the
problems of how to get things on and off the wire.
The hard problems in distributed computing concern dealing
with partial failure and the lack of a central resource manager.
The hard problems in distributed computing concern
insuring adequate performance and dealing with problems
of concurrency.
The hard problems have to do with differences in memory access paradigms between local and distributed entities. People attempting to write distributed applications quickly discover that they are spending all of
their efforts in these areas and not on the communications
protocol programming interface.