[Esip-discovery] Relating services to datasets served. Draft material for a DCP-3

Stephen Richard steve.richard at azgs.az.gov
Tue Sep 6 15:50:34 EDT 2011

If protocol is not expressed as an explicit attribute, a client has to parse
the URL to determine how to interact with the server (connection and request
sequence for ftp is different from http). The prefix on the url is
effectively the protocol attribute under the assumption that the scheme part
(before the ":") of a URL always uniquely defines the protocol at the
application layer in the standard OSI network stack framework.  Protocols
used by end user software (on top of OSI application layer) would be
specified by serviceType (if necessary). That can work and reduces the
number of attributes. How interesting is the use case of searching
specifically for links that use http or ftp? That would seem to be the only
reason to have an explicit protocol attribute. 

I shy away from using protocol as a link attribute based on the confusion
I've seen in use of  the protocol attribute in ISO19115 CI_OnlineResource
elements. The problem seems to be that there are various protocols operating
simultaneously at different network levels in almost any web operation.


>>> Here' s the gist of the proposal:
> >>
> >> href	the link URL
> >> type	MIME type of response. Specifies encoding and optionally the
> >> software application environment
> >> rel	URI from IANA rel vocabulary for consistency with IETF5988
> >> title	free text to label link in GUI
> >> esip:protocol	ftp, http, other. Default is http if attribute not
> >
> > I think we were looking for something a bit more specific here, like
"DAP" or
> "WMS".  ftp and http are unnecessary to specify, because they are in the
> itself.  Though if we use serviceType, then perhaps we do not
esip:protocol at
> all.
> Agree. Limit new attributes.
> >
> >
... DCP-1). The rest is supplemental information and background.
> >>
> >> steve
> >>
> >> Stephen M. Richard
> >> Arizona Geological Survey
> >> 416 W. Congress St., #100
> >> Tucson, Arizona, 85701   USA
> >> phone: 520 209-4127
> >> AZGS Main: (520) 770-3500.  FAX: (520) 770-3505
> >> email: steve.richard at azgs.az.gov

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