%% ---
%%  Excerpted from "Programming Erlang",
%%  published by The Pragmatic Bookshelf.
%%  Copyrights apply to this code. It may not be used to create training material, 
%%  courses, books, articles, and the like. Contact us if you are in doubt.
%%  We make no guarantees that this code is fit for any purpose. 
%%  Visit http://www.pragmaticprogrammer.com/titles/jaerlang for more book information.
%%---
-module(name_server).
-export([init/0, ns_add/2, ns_whereis/1, handle/2, go/0]).
-import(server1, [rpc/2]).

%% client routines
ns_add(Name, Place) -> rpc(name_server, {add, Name, Place}).
ns_whereis(Name)    -> rpc(name_server, {whereis, Name}).

%% callback routines
init() -> dict:new().

handle({add, Name, Place}, Dict) -> {ok, dict:store(Name, Place, Dict)};
handle({whereis, Name}, Dict)    -> {dict:find(Name, Dict), Dict}.
    
% test
go() ->
%    unregister(name_server),
    server1:start(name_server,name_server),
    ns_add(joe,home),
    ns_add(bob,work),
    {ok,home} = ns_whereis(joe),
    {ok,work} = ns_whereis(bob),
    error = ns_whereis(alice),
    ns_add(alice,hawaii),
    {ok,hawaii} = ns_whereis(alice),
    ns_add(bob,home),
    {ok,home} = ns_whereis(bob),
    ok.