Add capabilities property

[phillmac]

Define what optional functions are actually implemented in this controller, e.g. grant / revoke as a public static property

[shamb0t]

@phillmac Thanks for opening a PR. Can you elaborate on what you're trying to accomplish?

Also note that none of the access controllers currently support key revocation

[phillmac]

Basically from the api standpoint, I have no visibility into the grant / revoke functions that are actually present on a given controller. It'd be useful to have the ability to report for e.g. If this controller has grant implemented.

[shamb0t]

@phillmac could the same be achieved by calling the capability of interest in a try-catch block in the http-api? Not all access-controllers are required to adhere to those capabilities, and if others are added wouldn't it require listing them all in the interface?

[phillmac]

@shamb0t If the functions were just purely undefined and generated errors that'd be great, because the error would be feedback that the api call failed.
Currently the functions defined in the access-controller-interface silently return and to all apearances the api call suceeded.
See orbitdb-archive/orbit-db-http-api#20

[phillmac]

As you said there would be some interface overhead in maintaining a list of what controllers have what functions. A better solution would be very welcome!

[shamb0t]

@phillmac ah yes ofc they are already in the interface....hmm perhaps a quick fix could be changing grant and revoke in the interface to return false instead of a noop? That way if its not overridden as in the ipfs-access-controller case it will return false

[phillmac]

That'd be a lot better. I'll make another pr and close this one?

[shamb0t]

@phillmac that would be great!