Data Types

Here are the data types used by Ames, as defined in lull.hoon.


+$ address @uxaddress

Opaque atomic transport address to or from Unix. For Ames over UDP, it will encode the IP address and port.


+$ verb ?(%snd %rcv %odd %msg %ges %for %rot)

Verbosity flag for Ames. Use with |ames-verb %flag1 %flag2 ... and turn off with |ames-verb.

  • %snd - Sending packets.
  • %rcv - Receiving packets.
  • %odd - Unusual events.
  • %msg - Message-level events.
  • %ges - Congestion control.
  • %for - Packet forwarding.
  • %rot - Routing attempts.


+$ blob @uxblob

Raw atom to or from Unix, representing a packet.


+$ error [tag=@tas =tang]

Tagged diagnostic trace.


+$ lane (each @pC address)

Ship transport address; either opaque $address or galaxy. The runtime knows how to look up galaxies, so we don't need to know their transport addresses.


+$ plea [vane=@tas =path payload=*]

Application-level message, as a %pass.

  • vane - Destination vane on remote ship.
  • path - Internal route on the receiving ship.
  • payload - Semantic message contents.


+$ spar [=ship =path]

Instead of a fully qualifying scry path, Ames infers rift and life based on the ship.


+$ bone @udbone

Message flow index - mapped to ducts in the $ossuary.

The first bone is 0. They increment by 4, since each flow includes a bit for each message determining forward vs. backward and a second bit for whether the message is on the normal flow or the associated diagnostic flow (for naxplanations).

The least significant bit of a bone is:

  • 1 if "forward", i.e. we send %pleas on this flow.
  • 0 if "backward", i.e. we receive %pleas on this flow.

The second-least significant bit is 1 if the bone is a naxplanation bone, and 0 otherwise. Only naxplanation messages can be sent on a naxplanation bone, as %boons.


+$ fragment @uwfragment

A message fragment.


+$ fragment-num @udfragmentnum

Message fragment count.


+$ message-blob @udmessageblob

Unfragmented message blob.


+$ message-num @udmessagenum

Message count.


+$ public-key @uwpublickey

A peer's public key.


+$ symmetric-key @uwsymmetrickey

A symmetric key for encrypting messages to a peer. This is produced by performing an elliptic curve Diffie-Hellman using our private key and the peer's public key.


+$ ack
$% [%ok ~]
[%nack ~]
[%naxplanation =error]

A message acknowledgement.

  • %ok - Positive acknowledgement.
  • %nack - Negative acknowledgement.
  • %naxplanation - Nack trace.


+$ ship-state
$% [%alien alien-agenda]
[%known peer-state]

All Ames knows about a peer.

  • %alien - No PKI data, so enqueue actions to perform once we learn it.
  • %known - We know their life and public keys, so we have a channel.


+$ alien-agenda
$: messages=(list [=duct =plea])
packets=(set =blob)
heeds=(set duct)
keens=(jug path duct)

What to do when Ames learns a peer's life and keys.

  • messages - $pleas local vanes have asked Ames to send.
  • packets - Packets we've tried to send.
  • heeds - Local tracking requests; passed through into $peer-state.
  • keens - Subscribers to remote scry paths.


+$ peer-state
$: $: =symmetric-key
route=(unit [direct=? =lane])
snd=(map bone message-pump-state)
rcv=(map bone message-sink-state)
nax=(set [=bone =message-num])
heeds=(set duct)
closing=(set bone)
corked=(set bone)
keens=(map path keen-state)

State for a peer with known life and keys.

  • route - Transport-layer destination for packets to the peer.
  • qos - Quality of service; connection status to the peer.
  • ossuary - $bone to duct mapper.
  • snd - Per-bone message pumps to send messages as fragments.
  • rcv - Per-bone message sinks to assemble messages from fragments.
  • nax - Unprocessed nacks (negative acknowledgments).
  • heeds - Listeners for %clog notifications.
  • closing: Bones closed on the sender side.
  • corked: Bones closed on both sender and receiver.
  • keens: Remote scry state.


+$ keen-state
$: wan=((mop @ud want) lte) :: request packets, sent
nex=(list want) :: request packets, unsent
hav=(list have) :: response packets, backward
next-wake=(unit @da)
listeners=(set duct)

Remote scry state for a peer.

  • wan: Request packets, sent.
  • nex: Request packets, unsent.
  • hav: Response packets, backwards.
  • num-fragments: Total fragment count.
  • num-received: Fragments received.
  • next-wake: Retry timing.
  • listeners: Ducts waiting for a response.
  • metrics: Stats.


+$ want
$: fra=@ud

Remote scry request fragment.


+$ have
$: fra=@ud

Remote scry response fragment.


+$ meow
$: sig=@ux

Remote scry response fragment data.

  • sig: signature.
  • num: number of fragments.
  • dat: contents.


+$ peep
$: =path

Remote scry fragment request.


+$ wail
$% [%0 peep]

Tagged remote scry request fragment.


+$ roar
(tale:pki:jael (pair path (unit (cask))))

Remote scry response message.

A tale:pki:jael is a:

++ tale :: urbit-signed *
|$ [typ] :: payload mold
$: dat=typ :: data
syg=(map ship (pair life oath)) :: signatures
== ::

Therefore, a $roar looks like:

> *roar:ames
[dat=[p=/ q=~] syg=~]

In dat, for the (pair path (unit (cask))), the path is the remote scry path and the (unit (cask)) contains the value, or is null if there's no value at this path and will never be one (equivalent to the [~ ~] case of a local scry).


+$ purr
$: peep

Response packet payload.


+$ qos
$~ [%unborn *@da]
[?(%live %dead %unborn) last-contact=@da]

Quality of service; how is the connection to a peer doing?

  • %live - Peer is ok.
  • %dead - Peer is not responding.
  • %unborn - Peer is sunken.
  • last-contact - Last time Ames heard from the peer, or if %unborn, the time when we first started tracking then.


+$ ossuary
$: =next=bone
by-duct=(map duct bone)
by-bone=(map bone duct)

$bone to duct mapping, next is the next bone to map to a duct.


+$ message-pump-state
$: current=_`message-num`1
unsent-messages=(qeu message-blob)
unsent-fragments=(list static-fragment)
queued-message-acks=(map message-num ack)

Persistent state for a |message-pump.

  • current- Sequence number of earliest message sent or being sent.
  • next - Sequence number of next message to send.
  • unsent-messages - Messages to be sent after current message.
  • unsent-fragments - Fragments of current message waiting for sending.
  • queued-message-acks - Future message acks to be applied after current.
  • packet-pump-state - State of corresponding |packet-pump.


+$ static-fragment
$: =message-num

A packet; a fragment of a message and metadata.


+$ packet-pump-state
$: next-wake=(unit @da)
live=(tree [live-packet-key live-packet-val])

Persistent state for a |packet-pump.

  • next-wake - Last timer we've set, or null.
  • live - Packets in flight; sent but not yet acked.
  • metrics - Congestion control information.


+$ pump-metrics
$: rto=_~s1

Congestion control state for a |packet-pump.

  • rto - Retransmission timeout.
  • rtt - Roundtrip time estimate, low-passed using EWMA.
  • rttvar - Mean deviation of rtt, also low-passed with EWMA.
  • num-live - How many packets sent, awaiting ack.
  • ssthresh - Slow-start threshold.
  • cwnd - Congestion window; max unacked packets.


+$ live-packet
$: key=live-packet-key

A packet in flight, as tracked in the $packet-pump-state.


+$ live-packet-key
$: =message-num

Identifier of a packet in flight.


+$ live-packet-val
$: packet-state

Content and metadata about a packet in flight.


+$ packet-state
$: last-sent=@da

Sending statistics about a packet in flight.


+$ message-sink-state
$: last-acked=message-num
pending-vane-ack=(qeu [=message-num message=*])
live-messages=(map message-num partial-rcv-message)
nax=(set message-num)

State of a |message-sink to assemble received messages.

  • last-acked - Highest $message-num Ames has fully acknowledged.
  • last-heard - Highest message-num Ames has heard all fragments for.
  • pending-vane-ack - Heard but not processed by local vane.
  • live-messages - Partially received messages.


+$ partial-rcv-message
$: num-fragments=fragment-num
fragments=(map fragment-num fragment)

A message for which Ames has received some fragments.

  • num-fragments - Total number of fragments in the message.
  • num-received - How many fragments Ames has received so far.
  • fragments - The received fragments themselves.