This is one of many protocol behaviors described in ActivityPub.

Identifier

urn:uuid:4d1c969c-46ac-4e27-8ec9-7ff7ef25c47d

Content

The body of the POST request MUST contain a single Activity (which MAY contain embedded objects), or a single non-Activity object which will be wrapped in a Create activity by the server.

Origin

prefix The request MUST be authenticated with the credentials of the user to whom the outbox belongs.

The body of the POST request MUST contain a single Activity (which MAY contain embedded objects), or a single non-Activity object which will be wrapped in a Create activity by the server.
 
suffix Example 11: Submitting an Activity to the Outbox

https://www.w3.org/TR/activitypub/

JSON

{
  "id": "urn:uuid:4d1c969c-46ac-4e27-8ec9-7ff7ef25c47d",
  "type": "Behavior",
  "uuid": "4d1c969c-46ac-4e27-8ec9-7ff7ef25c47d",
  "content": "The body of the POST request MUST contain a single Activity (which MAY contain embedded objects), or a single non-Activity object which will be wrapped in a Create activity by the server.\n",
  "context": [
    "https://www.w3.org/TR/activitypub/",
    {
      "name": "Client to server interaction"
    },
    {
      "name": "clients posting Activities to an actor's outbox"
    }
  ],
  "origin": {
    "source": "https://www.w3.org/TR/activitypub/",
    "section": {
      "id": "https://www.w3.org/TR/activitypub/#x6-client-to-server-interactions",
      "branch": [
        6
      ]
    },
    "selector": {
      "type": "TextQuoteSelector",
      "prefix": "The request MUST be authenticated with the credentials of the user to whom the outbox belongs.\n",
      "exact": "The body of the POST request MUST contain a single Activity (which MAY contain embedded objects), or a single non-Activity object which will be wrapped in a Create activity by the server.\n",
      "suffix": "Example 11: Submitting an Activity to the Outbox\n"
    }
  },
  "@context": [
    "https://www.w3.org/ns/activitystreams",
    "https://socialweb.coop/ns/testing/context.json"
  ]
}