module Rpc_simple_client

: sig

Synchronous API for RPC clients

This is a synchronous client that suffices for most applications of RPC.

type t

The type of simple clients

val create : Rpc_client.connector -> Rpc.protocol -> Rpc_program.t -> t

Create a simple client that connects with the given server using the given protocol type. The program argument specifies the remote program.

val call : t -> string -> Xdr.xdr_value -> Xdr.xdr_value

call simple_client procedure_name procedure_arg: Call the procedure with the given name and the given argument. Returns the result of the procedure on success; otherwise raises an exception.

Note that it is possible that the connection is aborted and the client is reset. In this case call raises an exception but it is currently difficult to recognize this case. Other reasons may be that the server refuses the call (e.g. because of missing authentication).

Frequent exceptions:

  • Rpc.Rpc_server condition: The server did not like the call; the 'condition' explains why
  • Rpc.Rpc_cannot_unpack reason: Got a badly formatted message.
  • Rpc_client.Message_lost: The stream ended before there was any reply (perhaps not even the call could be sent over the stream)
  • Rpc_client.Message_timeout: There was no reply for the specified period of time
  • Rpc_client.Communication_error x: An I/O error or a serious internal error happened Failure s: Mostly: The internal state of the client does not allow to do another call

Note that only the Rpc_server exception has clear semantics as it is known that the procedure has not been invoked. It is a good choice to shut down the connection if one of the other exceptions happens. (Note that the connection may already have been shutted down, but it is ok to shut down twice.)

val shut_down : t -> unit

Shut the connection down. After the client has been shutted down, it is not possible to call further remote procedures. Throw the client away and create a new one if you want to continue.