Subscribers:V1 message format:

When service node receives a message, it verifies the signature and updates its Subscribers list (as a SOC / feed?). This is the format it expects:

{
overlay: <###>,
senderAddress: <Gnosis Address> ,
addSubscriptions: [ 
  resourceId: <string>,
],
removeSubscriptions: [
  resourceId: <string>,
],
signature: <hex>
}

TweetListener:V1 and TweetForwarder:V1 message formats:

When the service node gets a message at TweetForwarder:V1, it forwards the message to each node in its subscribers list which are listening in their own neighborhoods on the TweetListener:V1 subscription

{
    content: <string>,
    user: <string>,
    date: <date>
    etc...
}