rpc-framework

This is a framework for remote procedure calls in haskell.

Features

• Usage is incredibly simple!

• Calling a remote procedure is type safe.

• Modal logic inspired worlds, aka hosts:

  • Services run from the World IO monad, written Host w => WIO w
  • This allows world specific actions: if one world will be compiled to JS and one to x86, we could have the following types

    putStrLn :: IO_World w => WIO w a
    installTextBox :: JS_World w => WIO w ()

• Arbitrily complex remote procedures:
  • Rather than only being able to call a remote function of one argument, we can call with any number of arguments

    foo :: (Sendable a1 ,..., Sendable aN, Sendable b, Host w) => a1 -> ... -> aN -> WIO w b

• It can send pure functions across the wire and now garbage collect them.

    instance (Serializable a) => Sendable a a
    instance (Sendable a' a, Sendable b b') => Sendable (a -> b) (a' -> IO b')

• Only local code can execute

  • unlike some modal logic aproaches to mobile languages, the only code that can be executed is the code you compiled, and not code passed from world to world

• State can be serialized with references.

Usage

• To install, run cabal install

• Hosts are declared at the declaration level

    $(makeHost "WorldName" "host_location" #portNumber)

• Installing a remote service:
  • makeServices registers a list of service names which all have the same host
  • autoService automatically figures out which services in the given file run on the specified host and registers them. A good usage pattern is to provide all modules with services with a registration hook that can be appended to the main server.

    main = runServer $(makeServices [ 'nameOfService1, ... , 'nameOfServiceN])

    main = runServer $(autoService 'HostName)

    module First where
    services = $(autoService 'HostName)

    module Second where
    services = $(autoService 'HostName)

    module Main where
    import qualified First as F
    import qualified Second as S
    main = runServer $ F.services >> S.services

• Calling a remote service:

    addServer :: Integer -> WIO Server (Integer -> Integer)
    addServer t = do
        Server <- world
	return (t +)

    getRemoteAdd = $(rpcCall 'addServer)
    ...
    ghci> :t getRemoteAdd
    getRemoteAdd  :: Host w => Integer -> WIO w (Integer -> Integer)

Examples

• src/RPCTest.hs is an example.
  • It runs two worlds, Client and Server, both on localhost, one on port 9000 and the other on 9001.
  • To run and build it: make run
  • To build it: make test
  • To run it after building it: ./rpc-test