Is it possible to create a new post activity by reference?

[markcellus]

I'm attempting to post a new message to Mastodon via ActivityPub protocol. Per "The Message" section of the How to implement a basic ActivityPub server docs, it shows the Create Activity with an object that contains the Note contents in the object.content field.

However, I've already stored the note content on my blog at a proper URI (id). Is it possible to just link the new Create Activity to the post URI that is already available (maybe by omitting object.content and using object.url instead)? Or is the object.content required?

Just trying to avoid having a duplicate of my post on Mastodon. 😅

Thanks for any information!

[trwnh]

However, I've already stored the note content on my blog at a proper URI (id). Is it possible to just link the new Create Activity to the post URI that is already available

Does the URI accept the ActivityStreams profile and return a Note object in JSON-LD? If so, then yes, you can refer to it with a Create activity where object is just a bare IRI, I'm fairly sure

[markcellus]

Ah I see. Right now, the URI would just lead to the formatted HTML page of the blog entry. So it sounds like I'd have to make a new, separate URI that responds with the Note object in JSON-LD and just set object to that?

[trwnh]

Yes, but it can be the same URI if you set up your HTTP server to respond to Accept: application/ld+json; profile="https://www.w3.org/ns/activitystreams" properly. See https://www.w3.org/TR/activitypub/#retrieving-objects for more information

[markcellus]

Ah that's even better than what I was thinking! This is very helpful. Thank you so much 🥇