The DAIS CORBA API...

Some interesting but long reading ahead :-)

The OMG (managers of CORBA and UML) has a couple of CORBA specs that
are relevant to the Orocos project. One of these is the ``Data
Acquisition from Industrial Systems''. I cite from the report on
<http://cgi.omg.org/cgi-bin/doc?dtc/01-07-03.pdf>:

``The purpose of the DAIS API is to support efficient real time
transfer of large amounts of data from an industrial process to a wide
range of clients. It supports discovery of parameters and update of
parameter values. The DAIS is intended for on-line data transfer and
cannot be used to configure servers implementing the API.''
It doesn't support configuration, but it does support browsing of
unknown device interfaces.

The DAIS specs describe many things that are directly applicable to
robotics. For example, they discuss five communication patternsi (p.
4-21 and following in the DAIS specs):

- 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.
- 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.
Events and alarms are also supported. So, it could be worthwhile to
just copy these IDL interfaces?!

DAIS tries to be as OPC compliant as possible. OPC (`OLE for Process
Control', <http://www.opcfoundation.org/>) is a Microsoft-centric
project: `` The OPC Specification is a non-proprietary technical
specification that defines a set of standard interfaces based upon
Microsofts OLE/COM technology. The application of the OPC standard
interface makes possible interoperability between automation/control
applications, field systems/devices and business/office
applications.''

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