How to post a new toot to all followers

[markcellus]

I'm attempting to make a post to Mastodon using my own server via ActivityPub protocol. Per the "The message" section of the How to implement a basic ActivityPub Server docs, it says https://www.w3.org/ns/activitystreams#Public needs to be added to the to field. Is that all that's required? Or does the Activity need to specify each of my followers (ids) in order for my followers to see it? Thanks for any information that is provided!

[markcellus]

Ah, answered my own question. Essentially, I'll need to make a POST request to all inboxes of followers using the activity, per ActivityPub Delivery docs:

An activity is delivered to its targets (which are actors) by first looking up the targets' inboxes and then posting the activity to those inboxes.

@Gargron Would doing this without the https://www.w3.org/ns/activitystreams#Public still result in all followers seeing the new toot in their feeds? If so, what does Mastodon use the https://www.w3.org/ns/activitystreams#Public in the to field for? Thanks for any information!

[nightpool]

@markcellus the to and cc fields are used to determine the visibility of the post. having https://www.w3.org/ns/activitystreams#Public in the to or cc field marks your post as public, which means it can be displayed in hashtags, search, the federated timeline, other users can boost it, etc. if you don't include a to or cc property and just send your posts to someone's inbox directly, then only those people would be able to read it. does that make sense?

Additionally, Mastodon supports the idea of "shared inbox" delivery (7.1.3), which means that you only need to POST the activity only once per server, to the sharedInbox for that server. In that case, you'd want to use the ID of the followers collection that you've set up on your actor in the to field, so that Mastodon knows that it's a post to your followers. (along with as:Public if it's a public post)

[markcellus]

Yes, this makes a lot of sense @nightpool! Thank you. I'll use the shared inbox delivery method then, which is great. So if I understand correctly, with all irrelevant keys omitted, the Create activity object would have the following to value to post publicly and to followers on mastodon.social?:

// ie. POST to https://mastodon.social/inbox 
{
    to: [
        'https://www.w3.org/ns/activitystreams#Public', 
        <actor_id_of_follower1>, 
        <actor_id_of_follower2>, 
       // ...actor ids of all other followers here
    ]
}