Re: [dxwg] Service vs endpoint (#1242)

> I'd argue that the only services that makes sense to include as 'first class citizens' (geospatial or not) are processing services.

This was discussed at some length during the development of DCAT2. The key points are:

1. The simplest download service - which just gets a file from a file-system - might not merit a service description much beyond 'conforms to HTTP v1.1'. However, there is a rich spectrum beyond that. At the very least, even if the data is coming from a static datastore, there is usually a query mechanism to select an extract from the whole, both in terms of which records are retrieved, and which properties (columns). And a data service usually provides at least a method to project the result according to some 'schema' described in the request. Then there may be re-sampling, or coordinate transformation, or other processing as well. 

The client needs a way to find out about these options - selection/query operations, parameter ranges, response schema and format options - so there is a service description somewhere (maybe implied by the standard that it conforms to). 

2. Some services are tightly bound to a single datastore, some not. But even a processing service that can connect to multiple data sources is also initialized with (i.e. bound to) some 'data' - for example coordinate transformation parameters, or coefficients used in some other numeric. 

So I don't think it is so clear where the boundary between 'download' and 'processing' is. 

Every service we are interested in in the DCAT context delivers 'data'. Sometimes this is retrieved from a static(-ish) store. Sometimes generated on-the-fly somehow. But the client machine doesn't know and doesn't care what happens behind the interface. That's why, after an initial discussion about a small taxonomy of service-types, we decided to just have a single class `dcat:DataService`. 


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Received on Monday, 6 July 2020 02:21:04 UTC