Safe Haskell	Safe-Inferred
Language	Haskell2010

Capnp.Rpc.Membrane

Description

Membranes are common in object-capability design. Think of it like a proxy on steroids: a membrane inserts itself in front of another capability, and can intercept and modify method calls. Unlike a simple proxy though, the membrane will also be applied to any objects returned by method calls, or passed in arguments, transitively, so it can sit in front of entire object graphs.

Synopsis

enclose :: (IsClient c, MonadSTM m) => Supervisor -> c -> Policy -> m c
exclude :: (IsClient c, MonadSTM m) => Supervisor -> c -> Policy -> m c
type Policy = Call -> STM Action
data Action
- = Handle UntypedMethodHandler
- | Forward
data Direction
- = In
- | Out
data Call = Call {
- direction :: Direction
- interfaceId :: Word64
- methodId :: Word16
- target :: Client
}

Documentation

enclose :: (IsClient c, MonadSTM m) => Supervisor -> c -> Policy -> m c Source #

enclose sup cap policy wraps cap in a membrane whose behavior is goverend by policy.

exclude :: (IsClient c, MonadSTM m) => Supervisor -> c -> Policy -> m c Source #

exclude is like enclose, except that the capability is treated as being *outside* of a membrane that wraps the rest of the world.

type Policy = Call -> STM Action Source #

A Policy decides what to do when a call crosses the membrane.

data Action Source #

An action indicates what to do with an incoming method call.

Constructors

Handle UntypedMethodHandler	Handle the method using the provided method handler, instead of letting it through the membrane. Arguments and return values will not be wrapped/unwraped, so be careful when delegating to objects inside the membrane.
Forward	Forward the method call on to its original destination, wrapping and unwrapping arguments & return values as normal.

data Direction Source #

A Direction indicates which direction a method call is traveling: into or out of the membrane.

Constructors

In
Out

Instances

Instances details

Read Direction Source #
Instance details Defined in Capnp.Rpc.Membrane Methods readsPrec :: Int -> ReadS Direction # readList :: ReadS [Direction] # readPrec :: ReadPrec Direction # readListPrec :: ReadPrec [Direction] #
Show Direction Source #
Instance details Defined in Capnp.Rpc.Membrane Methods showsPrec :: Int -> Direction -> ShowS # show :: Direction -> String # showList :: [Direction] -> ShowS #
Eq Direction Source #
Instance details Defined in Capnp.Rpc.Membrane Methods (==) :: Direction -> Direction -> Bool # (/=) :: Direction -> Direction -> Bool #

data Call Source #

A Call represents a method call that is crossing the membrane.

Constructors

Call

Fields

direction :: Direction
Which direction is the call going? if this is In, the call was made by something outside the membrane to something inside it. If it is Out, something inside the membrane is making a call to something outside the membrane.
interfaceId :: Word64
The interface id of the method being called.
methodId :: Word16
The ordinal of the method being called.
target :: Client
The target of the method call.