Displaying VOEvents in Aladin through Plastic

[Alasdair Allan]

Just as a heads up for those of to whom this is new, the following  
comes out of a discussion John Taylor and I had at the VOTech DSRP  
meeting in Sorrento last week. For those of you on the VOEvent list,  
information about Plastic can be found at http:// 
plastic.sourceforge.net/

Thomas Boch wrote:
> John Taylor let me know you had some interest in using Aladin to  
> display
> VOEvents through a Plastic message. I am interested in knowing more
> about this ... Do you have a well-defined use case ? What kind of
> message should Aladin support to let you perform what you have in  
> mind ?
> This could be also discussed on the plastic-devs mailing-list.

The use case for pushing VOEvent messages via Plastic is two-fold, at  
least as far as I've got at the moment...

Firstly to inject a "hand-built" message into the VOEvent Network via  
a Broker or Relay. Secondly for the user's client software  
(recieveing a message from the network) to "hand" the message onto  
local display applications.

An event message is (almost always) include at the very least an RA  
and Dec inside the <WhereWhen> element. Additionally it could contain  
references to retrievable (or embedded) data products such as finding  
charts, actual data, spectra, light curves, or other tabular data.

In Aladin's case, at the basic level, I'd like it to consume a  
VOEvent message and plot the RA & Dec as a point. Yes, I could just  
push a ivo://votech.org/sky/pointAtCoords message to Aladin, but I'd  
like the option for more to be done...

Perhaps in future Aladin, or another display app, could parse the  
message and display all the applicable data products, e.g. retrieve  
and plot up a data image and the superimpose and error circle and co- 
ordinates of the event?

So I'd like to propose a,

ivo://votech.org/voevent/handleEvent

Arguments: xml: String
Returns: void

Where we pass a VOEvent XML message as a (escaped?) String into the  
Plastic application, which then returns a void.

What the application then does with this message is (of course) up to  
it!

Cheers,
Al.