Rational for implementation as service

[domwoe]

Hi @iamtxena,

nice work! Alternatively to defining an 'EidasService' you could have also added a new public key/verification Method type to the DID document. What are the reasons that the implementation introduces a new service type?

One reason I could think of is that x509 certificates/chains can be large. The service makes it clear that the certificate/chain has to be fetched from another location. In JSON-LD world nodes can either be embedded or linked to, so adding a linked to a verificationMethod is technically valid, but I'm not sure how processors would be configured in practice.

Thanks!