[[Clause_Requirements]]
== Requirements

=== Status Quo

There is currently no way for a service provider to advertise which services 
are available at an endpoint and do so in a way that is compatible with the
investments already made implementing OGC web service.  This is especially 
true for OGC catalogues which must be aware of every single endpoint that is
offered in order to be able to harvest the service metadata and make it
discoverable.

Furthermore, the associations that can be discovered between OGC services the,
content they offer and other OGC and non-OGC resources is very limited.
Currently, a client can interrogate an OGC web service's capabilities document
to discover what content it offers and perhaps and association to a metadata
document describing the content.

The inability to discover what OGC web services are available at an endpoint
and discover the rich associations that link OGC web services to the content 
that the offer and to other OGC and non-OGC resources significantly restricts
the usefulness of OGC cataogues and especially of CSW-ebRIM catalogue which
has the ability to capture all this information. 

=== Requirements Statement

In order to address the shortcomings of the status quo the following
requirements must be satisfied

. a means of advertising which OGC web services are available at an endpoint must be provided

. the means of discovering which OGC web services are available at an endpoint
should be compatible with the already significant software development
investment made implementing OGC web services (i.e. code reuse)

. a method must be provided that allows a OGC web services to be interrogated
to discover associations between the service, the content it offers and other
OGC and non-OGC resources

. the method of discovering associations should also provide a light-weight
query capability so the associations between specific resources or of a
specific association type can be requested

. the means of identifying resource must take into account that OGC resource
are typically identified by two pieces of information; the base URL of the
service offering the resource and a local identifier for the resource

. an extension package must to be defined for the CSW-ebRIM catalogue to
support rich discovery by allowing the catalogue to automatically harvest
services and their associations available at an endpoint