Integration

/ app.go

/ Register the AppModule for the fee middleware module
ModuleBasics = module.NewBasicManager(
    ...
    ibcfee.AppModuleBasic{
},
    ...
)

...

/ Add module account permissions for the fee middleware module
maccPerms = map[string][]string{
    ...
    ibcfeetypes.ModuleName:            nil,
}

...

/ Add fee middleware Keeper
type App struct {
    ...

    IBCFeeKeeper ibcfeekeeper.Keeper

    ...
}

...

/ Create store keys
    keys := sdk.NewKVStoreKeys(
    ...
    ibcfeetypes.StoreKey,
    ...
)

...

app.IBCFeeKeeper = ibcfeekeeper.NewKeeper(
	appCodec, keys[ibcfeetypes.StoreKey],
	app.IBCKeeper.ChannelKeeper, / may be replaced with IBC middleware
	app.IBCKeeper.ChannelKeeper,
	&app.IBCKeeper.PortKeeper, app.AccountKeeper, app.BankKeeper,
)

/ See the section below for configuring an application stack with the fee middleware module

...

/ Register fee middleware AppModule
app.moduleManager = module.NewManager(
    ...
    ibcfee.NewAppModule(app.IBCFeeKeeper),
)

...

/ Add fee middleware to begin blocker logic
app.moduleManager.SetOrderBeginBlockers(
    ...
    ibcfeetypes.ModuleName,
    ...
)

/ Add fee middleware to end blocker logic
app.moduleManager.SetOrderEndBlockers(
    ...
    ibcfeetypes.ModuleName,
    ...
)

/ Add fee middleware to init genesis logic
app.moduleManager.SetOrderInitGenesis(
    ...
    ibcfeetypes.ModuleName,
    ...
)

/ Create Transfer Stack
/ SendPacket, since it is originating from the application to core IBC:
/ transferKeeper.SendPacket -> fee.SendPacket -> channel.SendPacket

/ RecvPacket, message that originates from core IBC and goes down to app, the flow is the other way
/ channel.RecvPacket -> fee.OnRecvPacket -> transfer.OnRecvPacket

/ transfer stack contains (from top to bottom):
/ - IBC Fee Middleware
/ - Transfer

/ create IBC module from bottom to top of stack
var transferStack porttypes.IBCModule
transferStack = transfer.NewIBCModule(app.TransferKeeper)

transferStack = ibcfee.NewIBCMiddleware(transferStack, app.IBCFeeKeeper)

/ Add transfer stack to IBC Router
ibcRouter.AddRoute(ibctransfertypes.ModuleName, transferStack)

/ Create Interchain Accounts Stack
/ SendPacket, since it is originating from the application to core IBC:
/ icaAuthModuleKeeper.SendTx -> icaController.SendPacket -> fee.SendPacket -> channel.SendPacket

/ initialize ICA module with mock module as the authentication module on the controller side
var icaControllerStack porttypes.IBCModule
icaControllerStack = ibcmock.NewIBCModule(&mockModule, ibcmock.NewMockIBCApp("", scopedICAMockKeeper))

app.ICAAuthModule = icaControllerStack.(ibcmock.IBCModule)

icaControllerStack = icacontroller.NewIBCMiddleware(icaControllerStack, app.ICAControllerKeeper)

icaControllerStack = ibcfee.NewIBCMiddleware(icaControllerStack, app.IBCFeeKeeper)

/ RecvPacket, message that originates from core IBC and goes down to app, the flow is:
/ channel.RecvPacket -> fee.OnRecvPacket -> icaHost.OnRecvPacket

var icaHostStack porttypes.IBCModule
icaHostStack = icahost.NewIBCModule(app.ICAHostKeeper)

icaHostStack = ibcfee.NewIBCMiddleware(icaHostStack, app.IBCFeeKeeper)

/ Add authentication module, controller and host to IBC router
ibcRouter.
    / the ICA Controller middleware needs to be explicitly added to the IBC Router because the
    / ICA controller module owns the port capability for ICA. The ICA authentication module
    / owns the channel capability.
    AddRoute(ibcmock.ModuleName+icacontrollertypes.SubModuleName, icaControllerStack) / ica with mock auth module stack route to ica (top level of middleware stack)

AddRoute(icacontrollertypes.SubModuleName, icaControllerStack).
    AddRoute(icahosttypes.SubModuleName, icaHostStack).