  A message oriented software scheme is used for the SPring-8 beamline control.
In the early stage, we developed customized control programs for each beamline.
As the number of beamlines increased, however, it became necessary to introduce
a general software scheme that cloud handle the control sequence for every
beamline. We developed a new server program, Command Interpreter (CI), as a
software framework. The CI interprets a high-level compound message issued from
client programs and decomposes it to a set of primitive control messages. The
message are sent to the VME computers afterwards. For flexibility, the
operation sequences specific to the individual baemline component are
standardized and defined in the interface definition files. Using the CI, the
response time overhead is reduced to 26% and the XAFS measurement time also
decreases by about 50%.
