Review use of OpenID Provider and Issuer terms

[csarven]

I understand that the terms "provider" and "issuer" are brought forward from other specs and the context in which they are used matters. The Solid-OIDC spec may further benefit from reviewing the terms and where they are used, whether they are used interchangeably or in very specific context (e.g., roles, in code). For example, the section OIDC Issuer Discovery ( #oidc-issuer-discovery ) includes both "provider" and "issuer". There may be other instances in the document where that clarification can help.

[elf-pavlik]

The issuer terminology comes from https://openid.net/specs/openid-connect-discovery-1_0.html#IssuerDiscovery

2. OpenID Provider Issuer Discovery

OpenID Provider Issuer discovery is the process of determining the location of the OpenID Provider.

Issuer discovery is OPTIONAL; if a Relying Party knows the OP's Issuer location through an out-of-band mechanism, it can skip this step and proceed to Section 4.
[...]

Rel Type	URI
OpenID Connect Issuer	http://openid.net/specs/connect/1.0/issuer

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OP also is referenced as iss in the ID Token.

We can review the current use of those terms and see if something can be improved.

I would think of it in those lines

• oidc:Provider a rdfs:Class - names the type of OP
• oidc:issuer a rdf:Property - names the relation between the user and the OP