Harder than implementing RSS. Less hard than writing Linux from scratch. Where it lays in the middle depends a shitload on your requirements. How much you want to federate (a blog post VS conversations for instance), do you try for exact compatibility with existing services VS using a different activity type, is it one way or bidirectional, how does it need to scale, etc. I don’t know of a generic library you can use so you’d need to read and understand the spec.
Harder than implementing RSS. Less hard than writing Linux from scratch. Where it lays in the middle depends a shitload on your requirements. How much you want to federate (a blog post VS conversations for instance), do you try for exact compatibility with existing services VS using a different activity type, is it one way or bidirectional, how does it need to scale, etc.
I don’t know of a generic library you can use so you’d need to read and understand the spec.