Understanding Active Channels

The Interchain Accounts module uses ORDERED channels to maintain the order of transactions when sending packets from a controller to a host chain. A limitation when using ORDERED channels is that when a packet times out the channel will be closed.

In the case of a channel closing, a controller chain needs to be able to regain access to the interchain account registered on this channel. Active Channels enable this functionality. Future versions of the ICS-27 protocol and the Interchain Accounts module will likely use a new channel type that provides ordering of packets without the channel closing on timing out, thus removing the need for Active Channels entirely.

When an Interchain Account is registered using the RegisterInterchainAccount API, a new channel is created on a particular port. During the OnChanOpenAck and OnChanOpenConfirm steps (controller & host chain) the Active Channel for this interchain account is stored in state.

It is possible to create a new channel using the same controller chain portID if the previously set Active Channel is now in a CLOSED state. This channel creation can be initialized programmatically by sending a new MsgChannelOpenInit message like so:

msg := channeltypes.NewMsgChannelOpenInit(portID, string(versionBytes), channeltypes.ORDERED, []string{connectionID}, icatypes.PortID, icatypes.ModuleName)
handler := k.msgRouter.Handler(msg)

Alternatively, any relayer operator may initiate a new channel handshake for this interchain account once the previously set Active Channel is in a CLOSED state. This is done by initiating the channel handshake on the controller chain using the same portID associated with the interchain account in question.

It is important to note that once a channel has been opened for a given Interchain Account, new channels can not be opened for this account until the currently set Active Channel is set to CLOSED.