Registering SSA services

[Doug Tody]

Hi All -

We just concluded a registry/DAL telecon discussion on how to register
both the existing old/prototype SSA services, and new SSA services,
using the new registry (a major registry upgrade is in progress now and
this is the version we will want to use to register new SSA services).
What we came up with as a strawman plan is as follows:

    o   For the "prototype" spectrum services, which have a very
        different interface from SSA V1.0, we can merely register
        a working draft standard to identify these services, and
        use the identifier for this as the value of the StandardID
        attribute for these services.  These services will have no
        actual service-specific capability metadata, but that is the
        case currently as well.

    o   For SSA V1.0 and V1.1 we can (if we get it done in time for
        the registry update and SSA PR completion) develop a common
        SSA extension schema to be used for both versions.

        The version number will be used to differentiate between the
        two SSA service versions, otherwise they will be the same
        from the registry point of view.  In effect, the V1.1 schema
        will be able to describe V1.0 services.

        Since for V1.0 there is no getCapabilities operation,
        the capability metadata may be blank or have only default
        values.  In some cases a registry Web interface might be
        used to manually enter some of the metadata when a service
        is registered.

        For SSA V1.1 there will be a getCapabilities operation, and
        this will be used to automatically populate and maintain the
        service metadata in the registry.  getCapabilities will return,
        within a simple XML container defined by SSA, the SSA-defined
        "Capability" element for the service instance.  When the
        registry calls getCapability it will extract this capability
        element and update the contents in the VOResource instance
        for the service; no other resource metadata will be affected.

With the new registry, a client application should be able to search
for compatible services using a wildcard pattern match on the value
of the "StandardID' element.  By naming the standard identifiers
carefully we should be able to define and control how a client can
search for either prototype or standard SSA services (for V1.1 we
should probably mention this directly in the SSA specification).

It may also be possible to search on the actual capability metadata,
e.g., to find only services with certain capabilities.

        - Doug