A simple REST key-value store using the spooky framework.

kvstore.erl

-module(hello_world).
-behaviour(spooky).
-export([init/1, get/2, loop/1]).

init([])->
    %% register a process that holds our dict in memory
    case whereis(store) of
        undefined ->
            Pid = spawn(?MODULE, loop, [dict:new()]),
            register(store, Pid),
            io:format("store Pid=[~p]~n", [Pid]);
        Pid ->
            io:format("store already registered with Pid=[~p]~n", [Pid])
    end,
    [{port, 8000}].


get(Req, [])->
    Req:ok("/key to get value for key\n/key/value to set value");

get(Req, [Key, NewValue])->
    store ! {self(), Key, NewValue},
    receive Value ->
        Req:ok(io_lib:format("SET ~p=~p", [Key, Value]))
    end;

get(Req, [Key])->
    store ! {self(), Key},
    receive Value ->
        Req:ok(io_lib:format("GET ~p=~p", [Key, Value]))
    end.


loop(Dict) ->
    receive
        {Pid, Key, Value} ->
            NewDict = dict:store(Key, Value, Dict),
            Pid ! Value,
            loop(NewDict);
        {Pid, Key} ->
            case dict:find(Key, Dict) of
                {ok, Value} -> Pid ! Value;
                error -> Pid ! []
            end,
            loop(Dict)
    end.

Actually, you might be able to get away with just using the process dictionary, and skip all that 'store' process nonsense. You could also use Spooky's session dictionary. But I hope this is still a useful sketch for how to handle some more complex shared resource.

This has since spawned an unholy child with the bowling game example.