format=metadata in SSAP

[Patrick Dowler]

On 7.7.2005 01:18, Markus Dolensky wrote:
> Igor Chilingarian wrote:
> > 2) question to DAL WG: is there a way to distinguish between mandatory,
> > optional, and service-specific parameters on the level of format=metadata
> > response?
> 
> For the time being the recommended convention is to put mandatory + 
> optional (=reserved) parameter names in uppercase and service defined 
> once in lowercase. It is NOT valid to introduce service specific 
> parameter names by just changing the case of a reserved name.

Since the mandatory params are in the spec and all services will be compliant
at least with the mandatory ones (right? :-) the application already knows what
they are and that they will work. 

Similarly, the app knows what the list of optional params is and can check for
their presence. Anything else is service-specific.

That is, if we have the sets M (mandatory/spec), O (optional/spec) and
a service gives back P (params), then

M intersect P gives the available mandatory params (better be == M!)
O intersect P gives the available optional params (could be smaller than O)
P - (M union O) gives the service specific params

So, do we really need a way to tag this in the doc? I don't think so...

<note type="half-baked">
If the document returned from an SSA service had an application-specific
schema (ssa_result.xsd, say) then mandatory and optional params would
naturally be tags and service-specific params would have to be written in
some generic fashion where the param name was 'content' rather than a tag
or attribute name. In that case, one could easily differentiate. Also, this part
of the schema would also describe valid SSA queries... for the web service
days ahead.
</note>

-- 
Patrick Dowler
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