VODataService

VODataService is a XML Schema that extends the core VOResource schema to describe data collections and services that provide access to data. It forms the basis for extension schemas that describe support for standard IVOA protocols.

Working Draft Schema

VODataService-v1.0.xsd

Features

VODataService defines the follow extensions of the generic Resource type:

• DataCollection: describes a collection of data which can include a mix of images, catalogs, spectra and any other type of data. A collection description may include a description of coverage on the sky and in time and frequency, and it may include a description of the component catalogs.
• DataService: This is an extension of the Service Resource type that represents a service that provides access to data. One can describe the data's coverage on the sky and in time and frequency and its association with facilities and instruments.
• CatalogService: This is an extension of the DataService type to describe a service that provides access to data, and specifically interacts with or returns information in a tabular form. In addition to the DataService metadata, one may also describe the strucuture of the tables.
• STCStandard: This resource extension is used to define standard coordinate systems using STC.

It also defines an extension of the generic Interface type:

• ParamHTTP: this describes a service interface in the form an HTTP Get URL and comprised of a base URL and a set of arguments made up of key=value parameters. In this extension, it is possible to describe the input parameters supported by the service.

Some samples

• collection.xml
• catalog.xml
• stc.xml

Proposed Changes

These changes were proposed in Cambridge and were motivated by recent development work on the Simple Spectral Access (SSA) Protocol. The presentation here reflects the feedback provided during the Registry Working Group Session in Cambridge.

1. Add an optional <testArgs> to the ParamHTTP Interface type
   • Definition: a formatted set of arguments that, when applied to the access URL, can be used to test the service.
   • this mechanism is useful regardless of whether the service complies with a standard or not.
   • the format is a string such that when concatonated after the access URL, it produces a legal URL.
   • the arguments should be chosen such that the resulting query returns a legal, non-empty result.
2. Add an optional <rights> element to the DataService Resource type. DROPPED
   • This proposal has been dropped. When proposed, this was thought to be missing from DataService; however, it is included in the definition of the more general Service Resource type.
3. Add an optional <dataset> element to the DataService and DataCollection Resource types. DROPPED
   • provides a listing of Dataset identifiers that are available for use as input to the service
   • This proposal is being dropped as it does not address the original intended use of dataset IDs within SSA.

This change was motivated by recent work on TAP and VOSI.

1. Add extra elements to describe use of tables and databases.
   • Extra types are RelationalSchema, Function, RelationalJoin.
   • Two possible schema: one with mandatory nesting table in schema in catalog; one with the structure partially flattened.
   • XML schema with deeper nesting
   • XML schema partially flattened
   • The flatter schema allows all resources that validated against VODataService 1.0 to validate against VODataService 1.1.