Reply

To post a reply to a note, post an activity with verb "post" and an object with objectType "comment" and its "inReplyTo" property set to an object representing to original object.

{
    "verb": "post",
    "object": {
        "objectType": "comment",
        "content": "Hello, back!",
        "inReplyTo": {
            "id": "https://pump.example/api/note/XFRadkfr1_2kfkf",
            "objectType": "note"
        }
    }
}

You must include the id and objectType on the inReplyTo property; everything else is ignored.

Comment or note?

Should a reply be a comment or a note? If the reply is meant to stand on its own, and begin a new conversation, you can make it a "note". However, most replies should be "comments". If you're unsure, make it a "comment".

A good comparison might be blog comments versus "pingback" blog posts.