Summary off-list discussion on communication..

This is a short summary of an ongoing off-list discussion about the
design and implementation of the communication needs in Orocos:

- Anders Oreback and Christian Schlegel started implementing the basic
  communication patterns that we think would be necessary in Orocos.
  Basically, this means: send and receive, synchronous or asynchronous
  with callbacks/notifications.
- The development will follow concurrent routes and we will likely see
  two different (reference) implementations to be considered by the
  community.
  Takis in Leuven is (partly) following up these evolutions, but for
  the rest nobody has yet given any feedback.
- CORBA is an important factor in the discussions, especially because
  the version 3.0 specifications have made CORBA a lot more attractive
  (because simpler).
- The OMG group (the guys behind CORBA and UML standardization) hosts
  some developments in ``Manufacturing'' (and other domains), and one
  relevant development is the DAIS (Data Acquisition from Industrial
  Systems, <http://www.omg.org/cgi-bin/doc?dtc/01-09-03.pdf>), in
  which the following communication primitives are specified (completely
  with detailed CORBA model) on page 4-21:
   Read data: 
    - Synchronous read where the data is received at return from the
      sync_read() method. 
    - Asynchronous read where the data is returned at the Callback object.
    - Subscription where data is sent spontaneously by the server at
      the callback object. 
   Write data:
    - Synchronous write returning to the client once the all written
      data has reached the devices.
    - Asynchronous write returning when the data is received by the
      DAIS server. A callback on Callback is sent by the server once
      the written data has reached the devices.
  It could be worthwhile to follow an ongoing develompent in a very
  related domain, where a lot of manpower has already been devoted to
  the same problem as what we deal with in Orocos: data exchange between
  distributed components.
  The DAIS also specifies ``events and alarms''.

Herman

-- 
K.U.Leuven, Mechanical Engineering, Robotics Research Group
<http://www.mech.kuleuven.ac.be/~bruyninc>  +32 16 322480