a metadata config that adds entity attributes

[Tom Scavo]

I'm trying to develop a rather complex metadata configuration at the
SP. I haven't tested any of this yet but I wanted to ask if I'm on the
right track.

The MetadataProvider I have in mind has two <MetadataFilter> elements
and one <DiscoveryFilter> element (in that order). The first
<MetadataFilter> *adds* an entity attribute while the second
<MetadataFilter> filters away all entity descriptors that do not have
a special entity attribute. Finally, the <DiscoveryFilter> customizes
the discovery UI based on three entity attributes, one of which was
the entity attribute added at the beginning of the process.

Am I on the right track here? Thanks in advance. Tom

<!-- add a custom entity attribute to a particular entity descriptor -->
<MetadataFilter type="EntityAttributes">
    <saml:Attribute
            Name="http://macedir.org/entity-category-support"
            NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri">
        <saml:AttributeValue>http://example.org/category/research-and-scholarship</saml:AttributeValue>
    </saml:Attribute>
    <Entity>https://identityprovider.anl.gov/idp/shibboleth</Entity>
</MetadataFilter>

<!-- consume only InCommon metadata -->
<MetadataFilter type="Whitelist" matcher="EntityAttributes">
    <saml:Attribute
            Name="http://macedir.org/entity-category"
            NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri">
        <saml:AttributeValue>http://id.incommon.org/category/registered-by-incommon</saml:AttributeValue>
    </saml:Attribute>
</MetadataFilter>

<!-- expose all R&S IdPs on the discovery interface -->
<DiscoveryFilter type="Whitelist" matcher="EntityAttributes">
    <saml:Attribute
            Name="http://macedir.org/entity-category-support"
            NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri">
        <saml:AttributeValue>http://id.incommon.org/category/research-and-scholarship</saml:AttributeValue>
    </saml:Attribute>
    <saml:Attribute
            Name="http://macedir.org/entity-category-support"
            NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri">
        <saml:AttributeValue>http://refeds.org/category/research-and-scholarship</saml:AttributeValue>
    </saml:Attribute>
    <saml:Attribute
            Name="http://macedir.org/entity-category-support"
            NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri">
        <saml:AttributeValue>http://example.org/category/research-and-scholarship</saml:AttributeValue>
    </saml:Attribute>
</DiscoveryFilter>