Using the Atom Publishing Protocol, also known as AtomPub, you can add members to the Communities access control list, and make updates to the list.
Adding a community member programmatically
To add a member to the access control list of a community, send an Atom entry document containing the new member to the access control list feed. You can only add one member per post.
Retrieving a community member programmatically
To retrieve a member from the access control list for a application, use the edit link found in the member entry in the ACL list feed.
Updating community members
To update a member in the access control list for an application, send a replacement member entry document in Atom format to the existing ACL node's edit web address.
Deleting community members programmatically
To remove a member from the acl list for an application, use the HTTP DELETE method.