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Version: v9.0.x

Implementing the LightClientModule interface

Status method​

Status must return the status of the client.

  • An Active status indicates that clients are allowed to process packets.
  • A Frozen status indicates that misbehaviour was detected in the counterparty chain and the client is not allowed to be used.
  • An Expired status indicates that a client is not allowed to be used because it was not updated for longer than the trusting period.
  • An Unknown status indicates that there was an error in determining the status of a client.

All possible Status types can be found here.

This field is returned in the response of the gRPC ibc.core.client.v1.Query/ClientStatus endpoint.

TimestampAtHeight method​

TimestampAtHeight must return the timestamp for the consensus state associated with the provided height. This value is used to facilitate timeouts by checking the packet timeout timestamp against the returned value.

LatestHeight method​

LatestHeight should return the latest block height that the client state represents.

Initialize method​

Clients must validate the initial consensus state, and set the initial client state and consensus state in the provided client store. Clients may also store any necessary client-specific metadata.

Initialize is called when a client is created.

UpdateState method​

UpdateState updates and stores as necessary any associated information for an IBC client, such as the ClientState and corresponding ConsensusState. See section UpdateState for more information.

UpdateStateOnMisbehaviour method​

UpdateStateOnMisbehaviour should perform appropriate state changes on a client state given that misbehaviour has been detected and verified. See section UpdateStateOnMisbehaviour for more information.

VerifyMembership method​

VerifyMembership must verify the existence of a value at a given commitment path at the specified height. For more information about membership proofs see the Existence and non-existence proofs section.

VerifyNonMembership method​

VerifyNonMembership must verify the absence of a value at a given commitment path at a specified height. For more information about non-membership proofs see the Existence and non-existence proofs section.

VerifyClientMessage method​

VerifyClientMessage must verify a ClientMessage. A ClientMessage could be a Header, Misbehaviour, or batch update. It must handle each type of ClientMessage appropriately. Calls to CheckForMisbehaviour, UpdateState, and UpdateStateOnMisbehaviour will assume that the content of the ClientMessage has been verified and can be trusted. An error should be returned if the ClientMessage fails to verify. See section VerifyClientMessage for more information.

CheckForMisbehaviour method​

Checks for evidence of a misbehaviour in Header or Misbehaviour type. It assumes the ClientMessage has already been verified. See section CheckForMisbehaviour for more information.

RecoverClient method​

RecoverClient is used to recover an expired or frozen client by updating the client with the state of a substitute client. The method must verify that the provided substitute may be used to update the subject client. See section Implementing RecoverClient for more information.

VerifyUpgradeAndUpdateState method​

VerifyUpgradeAndUpdateState provides a path to upgrading clients given an upgraded ClientState, upgraded ConsensusState and proofs for each. See section Implementing VerifyUpgradeAndUpdateState for more information.