Proposal for server agnostic OID4VC handlers and adding fastify support

[sloops77]

Fastify is a http server that is maintained by some of the members of the core Nodejs team and is increasing in popularity. It is more focused on perforamnce and scalability and we have chosen it for our existing servers here.

We are exploring using Credo for OID4VC credential endpoints but would like to integrate those endpoints into our existing fastify-based servers, not express. We would like to propose therefore extracting out the server-agnostic code from the routers into handlers. The handlers would expect a requestContext (containing the agentContext, issuer & verifier), and could return json or throw exceptions. The routers would be retained for express implementation.

This would enable us to create equivalent routers for fastify, and we would be happy to contribute those if there were interest from the OWF for them.

WDYT?

[TimoGlastra]

I like the idea. I do think quite some complexity will be involved in defining an abstract http interface for Credo.

I think it makes sense to reuse the native web Request/Response interfaces.

We should also make these interfaces available for DIDComm, so it's possible to use the interface for all features of the framework.

Maybe you can come up with a design, and we could discuss it further? I think it would be great if you could also contribute your fastify adapter so it could be used by others