[webservices] New FDSN web services and retirement of deprecated services

[Chad Trabant]

Hello web services users,

We are pleased to announce that the IRIS DMC has implemented the International Federation of Digital Seismograph Networks (FDSN) versions of our core web services that support access to time series data, related metadata and event parameters.  The equivalent DMC services are now deprecated and will be retired, read more on that below.

The FDSN service specification defines an internationally recognized, standard interface.  Programs that access data via these FDSN web services should also be compatible with any other data center implementing FDSN interfaces.  There are a few, clearly marked IRIS extensions to the functionality that may not be implemented elsewhere.

These are an evolutionary step forward for DMC services and improve on what they are replacing in important ways.  For example, the time series web service now supports wildcards, and much more flexibility in selection style (supporting both GET and POST submissions and comma separated lists for channel name fields).


The fdsnws-dataselect service returns selected time series in miniSEED format:
http://service.iris.edu/fdsnws/dataselect/1/

The fdsnws-station service returns selected station metadata in FDSN StationXML and text formats:
http://service.iris.edu/fdsnws/station/1/

The fdsnws-event service returns selected event parameters in QuakeML and text formats:
http://service.iris.edu/fdsnws/event/1/

Our FDSN web services are available from a dedicated host name with new web documentation:
http://service.iris.edu/

Comments, feedback and questions are welcome.


== Transitioning clients to the FDSN services

The DMC has converted it's Perl-based Fetch scripts to use these new services, the latest version may be downloaded from here:

http://service.iris.edu/clients/

The transition of the IRIS Java Web Services library and the irisFetch.m for MATLAB are currently in progress.


== Deprecation of equivalent IRIS services

With the release of our FDSN services we are deprecating the equivalent services.

These services will be turned off in approximately 6 months:

ws-bulkdataselect (www.iris.edu/ws/bulkdataselect)
ws-dataselect (www.iris.edu/ws/dataselect)
ws-station (www.iris.edu/ws/bulkdataselect) 
ws-event (www.iris.edu/ws/event) 


== Differences between FDSN and the services they are replacing

The FDSN web services return HTTP status code 204 to indicate "No data" as opposed to status code 404 used by the services they are replacing.  The behavior of returning a 404 can be restored by including the 'nodata=404' parameter and value in the request.

fdsnws-dataselect is a combination of the capabilities of ws-bulkdataselect and ws-dataselect:
 1) enhancement: the network, station, location and channel selections may be comma-separated lists (e.g. BHE,BHN)
 2) enhancement: the network, station, location and channel selections may contain * and ? wildcards
 3) should be a drop-in replacement for ws-bulkdataselect (accepts the same requests via POST).
 4) a near complete replacement for ws-dataselect (accepts GET requests with parameters) except that it does not support the 'ref' parameter and does not support caching in the internal ICAB system.

fdsnws-station is equivalent to ws-station with these important changes:
 1) the XML output is returned as FDSN StationXML, a different schema
 2) new 'matchtimeseries' parameter to limit results to channels with high probability of data at the DMC
 3) the 'output' parameter name is changed to 'format'

The FDSN StationXML schema (http://www.fdsn.org/xml/station/) is generally equivalent to the XML format previously used but it is a distinctly different schema that cannot be parsed with the same software parsing the XML from ws-station.

fdsnws-event is equivalent to ws-event with these differences:
 1) the FDSN service returns event depths in meters to conform to QuakeML 1.2 (the ws-event service used kilometers)
 2) the 'output' parameter name is changed to 'format'
 3) only a single catalog can be selected per-request, the default catalog is 'NEIC PDE'
 4) in addition to the default order of descending results, the 'orderby' parameter can be 'time-asc' or 'magnitude-asc' to set the order to ascending.

IRIS Web Services team





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