OCaml-RPC

ocaml-rpc is a library that provides remote procedure calls (RPC) using XML or JSON as transport encodings. The transport mechanism itself is outside the scope of this library as all conversions are from and to strings.

RPC types

An RPC value is defined as follow:

type t =
  | Int of int64
  | Bool of bool
  | Float of float
  | String of string
  | DateTime of string
  | Enum of t list
  | Dict of (string * t) list
  | Null

Generating code

The idea behind ocaml-rpc is to generate functions to convert values of a given type to and from theirs RPC representations.

In order to do so, it is sufficient to add [@@deriving rpc] to the corresponding type definition. Hence :

type t = ... [@@deriving rpc]

this will give two functions:

• A function to convert values of type t to values of type Rpc.t : val rpc_of_t : t -> Rpc.t

• A function to convert values of type Rpc.t to values of type t : val t_of_rpc : Rpc.t -> (t,string) Result.result

Optionally, it is possible to have different field name in the OCaml type (if it is a record) and in the dictionary argument (the first elements of Dict):

type t = { foo: int [@key "type"]; bar: int [@key "let"]; } [@@deriving rpc]

This will replace "foo" by "type" and "bar" by "let" in the RPC representation. This is particularly useful when you want to integrate with an existing API and the field names are not valid OCaml identifiers.

Conversion functions

rpc currently support two protocols: XMLRPC and JSON(RPC). Functions signatures are:

val Xmlrpc.to_string : Rpc.t -> string
val Xmlrpc.of_string : string -> Rpc.t
val Jsonrpc.to_string : Rpc.t -> string
val Jsonrpc.of_string : string -> Rpc.t

So if you want to marshal a value x of type t to JSON, you can use the following function:

Jsonrpc.to_string (rpc_of_t x)

Dependencies

• xmlm
• ppx_deriving
• type-conv (for deprecated camlp4 extension)