Implement storage description resource discovery

[csarven]

https://solidproject.org/ED/protocol#server-storage-description details the discovery of the storage description resource.

Servers MUST include the Link header field with rel="http://www.w3.org/ns/solid/terms#storageDescription" targeting the URI of the storage description resource in the response of HTTP GET, HEAD and OPTIONS requests targeting a resource in a storage.

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solid/specification#355 (comment) shows how an application (e.g., https://dokie.li/ ) makes use of such resource to discover the features of the storage. Some common use cases are mentioned in solid/specification#355 (comment)

[sumeetkolekarr]

Can I take this issue?

[csarven]

@sumeetkolekarr Please do!

lib/header.js may be one of the places where you want to look into. For example, I've done something like this:

addLink(res, 'https://csarven.localhost:8443/storage-description', 'http://www.w3.org/ns/solid/terms#storageDescription')

Essentially you may want to start with any non-auxiliary resource (i.e., with the exception of resources referred by describedby or acl) to have a storageDescription relation to the description resource that the storage also refers to. (Another way of saying that is that the storage root, e.g., / has link header relations for http://www.w3.org/ns/solid/terms#storageDescription and describedby and they both link to the same resource e.g., https://csarven.localhost:8443/storage-description - they can potentially be different resources, but there is no strong argument to have them separate at this time, so I suggest keeping it simple. If I'm not mistaken, NSS's describedby for the root container / is /.meta, so all containers and non-containers in the storage can simply do this:

addLink(res, 'https://csarven.localhost:8443/.meta', 'http://www.w3.org/ns/solid/terms#storageDescription')

Happy to support further if you have any questions.

[sumeetkolekarr]

Kindly Assign me and I will work on it right away!

[bourgeoa]

@sumeetkolekarr branch issue#1805 has been created

[sumeetkolekarr]

@bourgeoa Perfectly noted!