Custom HTTP headers of TAP-VAMDC

“TAP-VAMDC” is the working title for the emerging data-access services that return data in XSAMS format. To provide the easily-accessible statistics of the response document, several custom HTTP headers were defined. They are reported for both HTTP HEAD and HTTP GET queries to the TAP-VAMDC sync endpoint.

Statistics

The following headers represent document statistics, all should be integer numbers.

• VAMDC-COUNT-SPECIES

  Total count of the atomic Ion and Molecule records with distinct SpecieID attribute.

• VAMDC-COUNT-ATOMS

  Count of the atomic Ion records with distinct SpecieID attribute.

• VAMDC-COUNT-MOLECULES

  Count of the Molecule records with distinct SpecieID attribute.

• VAMDC-COUNT-SOURCES

  Count of distinct Source records

• VAMDC-COUNT-STATES

  Count of distinct State records, both AtomicState and MolecularState combined

• VAMDC-COUNT-COLLISIONS

  Count of the CollisionalTransition elements of the Processes branch of XSAMS.

• VAMDC-COUNT-RADIATIVE

  Count of the RadiativeTransition elements of the Processes branch of XSAMS.

• VAMDC-COUNT-NONRADIATIVE

  Count of the NonRadiativeTransition elements of the Processes branch of XSAMS.

With a reasonable database layout the nodes should easily be able to gather these numbers by running COUNT queries on their corresponding tables.

Volume limitation

A TAP-XSAMS service can limit the amount of data it returns via the synchronous interface, for example to prevent the fetching of the whole database or for performance reasons. The service may then fill the HTTP-header of the response with the field VAMDC-TRUNCATED that indicates the percentage

VAMDC-TRUNCATED: 2.9 %

Document size estimate

VAMDC-APPROX-SIZE HTTP header is intended to provide the estimation of the size of the response document. It should return an integer value, representing estimate uncompressed document size in megabytes.