IBC Channel functionality

[adizere]

Context

IBC Channels build on top of IBC connection. Channels provide exactly-once and optional ordering semantics for message delivery in IBC.

Further reading

ICS04: ics-004-channel-and-packet-semantics
ICS05 ics-005-port-allocation
TLA+ spec for ICS04 packet handlers: ICS04PacketHandlers.tla as part of IBC Core TLA+ spec

Dependencies

The implementation of Channel depends on:

• ICS02: ics-002-client-semantics
• ICS03: ics-003-connection-semantics
• ICS05 ics-005-port-allocation

For complete implementation & acceptance:

• ICS26: ics-026-routing-module
• ICS18: ics-018-relayer-algorithms
• model-based testing (MBT) harness

Acceptance criteria

Component	Functionality	Criteria	Status
Module	Channel Open Handshake Handlers	Impl & unit tests	[X]
Module	Channel Open Handshake Handlers	MBT tests	[ ]
Module	Channel Open Handshake Handlers	TLA+ spec	[X]
Module	Channel Close Handshake Handlers	Impl & unit tests	[X]
Module	Channel Close Handshake Handlers	MBT tests	[ ]
Module	Channel Close Handshake Handlers	TLA+ spec	[X]
Module	Port allocation & authentication	Impl & unit tests	[ ]
Module	Packet (Send, Recv, Ack, Timeout) Handlers	Impl & unit tests	under review
Module	Packet (Send, Recv, Ack, Timeout) Handlers	MBT tests	[ ]
Module	Packet (Send, Recv, Ack, Timeout) Handlers	TLA+ spec	[ ]
Module	Verification methods for all ICS04 functionality	Impl & mock tests	[ ]
CLI	Channel handshake	Impl & end-to-end tests	[X]
CLI	Packet relaying commands (send, recv)	Impl & end-to-end tests	[X]
CLI	Packet relaying with delay	Impl & end-to-end tests	under review
CLI	Automatic Packet relaying (Relayer start)	Impl & end-to-end tests	[ ]

Related issues

The following ongoing issues provide a more fine-grained perspective on the different parts of IBC client functionality:

• Handler for Packets (ICS 004) Handler for Packets (ICS 004) cosmos/ibc-rs#101
• Reactive relayer architecture for packets relaying and channel/connection handshakes Reactive relayer architecture for packets relaying and channel/connection handshakes #764
• Relay for all paths defined in the configuration Relay for all paths defined in the configuration #748
• Rework ibc::ics04_channel::events module Rework ibc::ics04_channel::events module cosmos/ibc-rs#86
• Add CI test for the relayer loop Add CI test for the relayer loop #708
• Implement MBT for ICS04 Channel handlers Implement MBT for ICS04 Channel handlers cosmos/ibc-rs#30
• Implement packet delay in packet relaying Implement packet delay in packet relaying #640