ejrpc2

Erlang JSON-RPC 2 Utility

Example

Given a module testmod:

-module(testmod).
-export([subtract/2]).

subtract(X, Y) ->
  X - Y.

On the erlang shell:

1> Str = "{\"jsonrpc\":\"2.0\", \"id\":1, \"method\":\"subtract\", \"params\":[250,3]}",
2> {ok, R, _} = ejrpc2:handle_req(testmod, Str).
3> io:format("Output: ~s~n", [R]).
Output: {"jsonrpc":"2.0","result":247,"id":1}
ok

Usage of ejrpc2:handle_req(Mod, Str, Opts).

• Mod
  • can either be a module name (atom), a module name and options {module(), mod_options()}, or a list of these two sorted according to priority.
  • module options:
    • {prefix, Prefix} - effective method names will be prefixed by Prefix followed by a '.'
• Str is the name of the method
• Opts is a list of one or more of the following
  • {preargs, [any()]} - pre arguments
  • {arbitrary_json_h, fun/1} - callback for valid json, but invalid json-rpc2
  • {default_eterm, any()} - sets the default Erlang term to return for the handler

JSON-RPC2 Callbacks should return either:

• {ok, json()}
• {ok, json(), any()}
• {error, ErrCode, ErrMsg}
• {error, ErrCode, ErrMsg, any()}
• json() - equivalent to {ok, json()}

Notes

• Internal JSON encoding/decoding is done This uses mochijson2 from Mochiweb.
• Mochiweb is distributed under the MIT License.