Re: Libraries for working with STC?

Hi.
Three weeks ago I sent message quoted below.

>
> On 21 Jul 2008, at 17:28, Noel Winstanley wrote:
>> Hi,
>> In voexplorer, I'd like to present resource coverage information
>> in an astronomer-friendly manner. The coverage of a service is
>> described in a registry resource by a block of STC/x.
>>
>> Does anyone know of a library / xslt / webservice that can convert
>> STC/x into something (such as STC/s) that is more readable?
>>
>> I'd hoped to find an xslt stylesheet that converted from STC/x to
>> STC/c (to my mind, surely is required by the standard to define
>> the equivalence of the two representations), but I've had no luck
>> so far.
>>

I think I should feed back to the lists what I've found:

Well, I've not managed to find a solution for the problem described above (I need a library or service I can call from a Java desktop application).

In fact, no-one replied to my request on-list.

Off-list, I was informed of two pieces of software that process STC:

• Starlink AST (http://www.starlink.ac.uk/ast ) is a C library for coordinate conversion which implements an early draft of STC. AFAIK, there's no plans to support the STC standard.
• The Footprint Service at http://voservices.net/footprint/ allows the user to upload a STC description and then download it in different formats. However, this functionality doesn't seem to be programmatically callable as a webservice. I've asked whether the implementation could be open-sourced or shared in some way, but haven't yet heard back.

Off-list, I also received a number of very negative responses. Typical quotes include:

> Welcome to VO world, where just spec exists and
> nobody cares about implementing them.

and

> Hah! You'll be lucky. STC/anything wasn't distinguished by
> multiple implementations. It was distinguished by having no
> complete implementations at all. That's what standards are for, eh?

Other replies were even more emphatically pessimistic.

So, I'm hardly encouraged! Now, I could dive down the rabbit hole and try to implement my solution from scratch - but I'm surprised that there's been so little implementation of STC so far, considering the central place it takes in the IVOA standards (as re-emphasized in sect 3.4 of the 2008 IVOA roadmap).

Considering the negative replies, I'm wondering whether there's some technical / software engineering barriers to implementing STC parsers and transformers. Can anyone else share their experience of even _attempting_ to work with STC?

Finally, I spotted in the 2008 IVOA roadmap (section 2.4) that one of the activities for the DM workgroup this year is to

> 1) Improve and facilitate the uptake of the existing IVOA
> specifications: STC,
> Characterisation and Spectrum data models.
> * Develop a library for STC classes
>

Which sounds like an excellent idea. Could I ask who it is that's working on this, and what the planned implementation language and functionality is to be? If it looks like it'll solve the problem described in my original email, I"d be glad to assist.

cheers
Noel Winstanley

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Senior Developer, AstroGrid Project.
University of Manchester