Synchronous API for RPC clients
This is a synchronous client that suffices for most applications of RPC.
The type of simple clients
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).
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.)