Apps Messaging - Twin track?

[Mike Fitzpatrick]

I've posted some use cases I don't think PLASTIC solves on the
twiki at

 http://www.ivoa.net/twiki/bin/view/IVOA/ApplicationsMessagingUseCases

To be honest, with painful contortions I could probably do each of these
(and will likely think of others) but that isn't the point here.  I'll
include the
text here for easier rebuttal.

-Mike

Use-Cases Not Handled (Eleganty) by PLASTIC

1)  I have some legacy Fortran code that does the world's greatest N-body
    simulation of globular cluster evolution.  I would like to plot the
    evolution at each iteration using VOPlot.

    Missing Concept:  Language support for legacy environments not directly
        supporting XML-RPC or RMI.

2)  I have code that computes a deblended spectral profile of an eclipsing
    binary.  I would like to plot the spectrum, zoom in on a particular
    line and overplot my best fit to that feature by sending the data from
    my fit (without writing an intermediate file).

    Missing Concept:  A data payload with the message instead of a simple
        file reference.

3)  I have an instrument simulator (I *really* do) that creates an
    observation sequence by triggering an action in a "head" process that
    then cascades to multiple processes controlling different areas of a
    detector.  As each process completes it should send a 'done' message
    back to the head node, when all replies are received the trigger process
    is given a 'done' to complete the observation.  Procs in the chain all
    know only a 'start' and 'done' message but messages are broadcast based
    on the type of work they do.  (Note the same example could apply in a
    pipeline or distributed workflow).

    Missing Concept:  The idea of "message groups", i.e. apps can identify
        themselves as belonging to a special-interest 'group' rather than
        simply as having some functionality or handling some data type.
        Messages can be broadcast only to this group,  apps can enroll in
        any group but ignore specific messages they cannot handle (e.g.
        subscribe to the 'plot' group but reject a request to plot a
        spectrum on a wavelength scale).

4)  a) I want to display a 2-D image to any application capable of rendering
       it on the screen for me.
    b) I want to do the same but only if the app can accept a URL insstead
       of a local file name,
    c) I want to display an image to a specific frame/plane of the
       app so I can load it for an animation/blinking.
    d) I want to display an image to a specific region of the image display
       window (e.g. as part of a detector mosaic)

    Missing Concept:  Ability to query and/or exploit specific capabilities
        of an application.

5)  I want to sent all connected apps a message to "cd" to a specific
    directory so that subsequent file references will have them see the
    same files my app sees.

    Missing Concept:  "Context Messages" to create a unified view of the
        desktop between all applications.

6)  I want to invoke a task on an app with a command shell environment.  The
    app requires some method to invoke a task and optional arguments.  It may
    or may not return a response message other that a status, it may also
    produce a new data product that can be referenced later by name.

    Missing Concept:  Well, ...IRAF