[evla-sw-discuss] Notes from Scripting Walk-through Meeting

[Kevin Ryan]

Some notes from Kevin.

1)
> The Antenna object sets up ... stuff in the correlator front-end - the
> station board.

Antennas do not know about correlators, they are antennas.  If they
contained correlators then they would know about them, but they don't.
Likewise, correlators do not contain antennas.

The Array contains both antennas and correlators (and other things
like weather stations) so that is the logical place to broker
information and control between those things, I think.

2) I believe that much of what is contained in Barry's control
scripts should actually reside in the control systems themselves
(i.e. the correlator controller, antenna controller, array
controller, etc.).  Here is why:

I do not like the notion of the observing scripts having to know
about such things as software objects and how hardware control is
implemented.

These should be observing scripts not 'control' scripts.  They should
contain *what* the system should do and *when* it should be done.
Nothing more.  The control systems (which know more about the thing
they are controlling then anyone else) will take care of carrying out
the orders.

If the observe script contains only what/when data, it can be used by
any system.  This is the idea behind Brent's Virtual Correlator and
our RadioTelescopeInterface which will supply the list of available
'whats'.  Our Antenna Class implements this interface and from it
will extend the VlaAntenna, EvlaAntenna, VlbaAntenna and NmaAntenna
for now and maybe more types later.

An Observing system that can talk to a RadioTelescopeInterface will
be compatible with any of these antennas.

In summary - keep hardware and software details out of the observe
layer, that is what the control systems are for.

3)  A while back Jim U. spoke about Fred Lo's desire to make our
systems easier to use so that more people will use them.  The
scripts are the user's interface to our systems.  As such, this
first cut of scripts are too complex.

I agree with Rich that the observe scripts should be data only and
in a standardized markup language format such as XML - simplifying
things for the user.

Kevin

P.S.  I am not advocating 'dumbing' down operation of the system
to the point that it is useless.  Expert users should still be
able to tweek the smallest, most hidden control parameter.  It's
just that those who don't want to tweek it should not have to.