Channel

Subprotocol name: ripple-channel.

For an explanation of this subprotocol, see Advertisements.

Channel List Request

{

    "type": "channel-list-request",
    "request-id": (integer)

}

Channel List

{

    "type": "channel-list",
    "request-id": (integer)
    "body": [
        (channel data structures)
    ]

}

Channel Data Structure

(string)

Channel Subscribe

{

    "type": "channel-subscribe",
    "body": [
        (channel data structures)
    ]

}

Channel Unsubscribe

{

    "type": "channel-unsubscribe",
    "body": [
        (channel data structures)
    ]

}

Channel Ad

{

    "type": "channel-ad",
    "from": [
        (list of nodes on the sending host that are potential intermediaries 
        to the ad's source for interested nodes on the receiving host)
    ]
    "body": {
        "content": (URI),
        "source": (Ripple ID),
        "channels": [
            (channel data structures)
        ]
        ("min-amount": (decimal),
        "units": (URI),)
        ("onion": (routing onion data structure),)
    }

}

Notes:

content URI should be HTTP-accessible and contain the content of the ad, so hosts don't have to transfer the same ad content over and over
URI also acts as ID for the ad
To save bandwidth, a host is not required to send the same channel-ad to a node (on another host) more than once. (Same means same URI.)
Perhaps there needs to be a way to address channel-ad to multiple nodes on the same host simultaneously in a single message...?