Relaying of Handshake Messages

This section describes the configuration and commands that can be used to start the relayer and relay both handshake and packets for connections and channels.

The start Command

To relay packets and handshake messages configure the mode section of the configuration file like so:

[global]
log_level = 'info'

[mode]

[mode.clients]
enabled = true
# ...

[mode.connections]
enabled = true

[mode.channels]
enabled = true

[mode.packets]
enabled = true
# ...

Then start hermes using the start command:

hermes start

The relayer sends handshake and packet transactions triggered by IBC events.

Completing Channel Handshakes

After the relayer is started using the start command, it scans the chain state and will resume the handshake for any channels or connections that are not in open state. It then listens to IBC events emitted by any of the configured chains.

Assuming the events are coming from a source chain, the relayer determines the destination chain and builds the handshake messages based on these events. These are then sent to the destination chain.

In addition to the events described in Packet Relaying, the following IBC events may be handled:

  • Channels (if mode.channels.enabled=true):

    • chan_open_init: the relayer builds a MsgChannelOpenTry message
    • chan_open_try: the relayer builds a MsgChannelOpenAck message
    • chan_open_ack: the relayer builds a MsgChannelOpenConfirm message
    • chan_open_confirm: no message is sent out, channel opening is finished
  • Connections (if mode.connections.enabled=true):

    • conn_open_init: the relayer builds a MsgConnOpenTry message
    • conn_open_try: the relayer builds a MsgConnOpenAck message
    • conn_open_ack: the relayer builds a MsgConnOpenConfirm message
    • conn_open_confirm: no message is sent out, connection opening is finished