I recently found out about a cool software collaboration site: Stackoverflow. There one can get questions answered in a timely manner as well as earning "reputation" credits. Access is free and unlimited akin to a "wiki" site such as Wikipedia.
As a stepping-stone towards making the browser my main portal to my applications, I have crafted a Google Chrome extension (based on an NPAPI plugin) that lists the services announced through Avahi / mDNS.
It is available here. Note that only Linux based systems are supported.
I am sharing the following diagram to (hopefully) lessen some pain from folks who intend to write NPAPI based plugins (Firefox, Chrome etc.).
STEP 1: the host browser loads the library corresponding to the MIME type expressed in the embed element tag.
For those adept of Stackoverflow, the following extension provide tweaks to the web site. For version 0.1, the questions associated with ignored tags are rendered hidden.
When working on Linux, it is hard to ignore DBus for communicating with applications around the Desktop. Since I love Erlang so much, I wanted the capability to interface with DBus through Erlang scripts and/or applications hence I crafted an interface library.
I was recently playing around with ejabberd crafting myself a module in Erlang. I require the module to communicate with an external node through the RPC facility. Of course, Erlang mandates having the same cookie value throughout a node domain. To make matters worse, ejabberd does not appear to allow configuring the said cookie.
I've written Linux daemons in Python & C/C++ before and I must say that enough documentation is available online to make this experience as smooth as I believe it can be. Granted there are some interesting cases to take care of (e.g. zombies) but overall the procedure is fairly straightforward. Now my new found love in Erlang brings me once again to writing daemons.
#!/usr/bin/env escript
%% -*- erlang -*-
%%! -sname etrx_control
%%
%% @author Jean-Lou Dupont
%%
code_ok() -> 0.
code_error() -> 1.
code_daemon_found() -> 2.
code_daemon_not_found() -> 3.
code_lib_not_found() -> 4.
code_node_not_found() -> 5.
err_lib() -> "erlang-transmission not found".
err_daemon() -> "daemon not found".
err_node() -> "transmission node not found".
msg_pid() -> "daemon found, pid: ".
msg_usage() -> "usage: etrx_control [-q] [status|stop]".
msg_kill() -> "stop command sent".
main(["-q", "stop"]) -> run(quiet, stop);
main(["-q", "status"]) -> run(quiet, status);
main(["stop"]) -> run(verbose, stop);
main(["status"]) -> run(verbose, status);
main([]) ->
msg(verbose, code_ok(), msg_usage()),
halt(code_ok());
main([_Cmd]) ->
msg(verbose, code_ok(), msg_usage()),
halt(code_error()).
run(Feedback, stop) ->
add_cwd(),
case getstatus() of
daemon_not_found ->
msg(Feedback, code_daemon_not_found(), err_daemon());
{pid, Pid} ->
os:cmd("kill -9 "++Pid),
msg(Feedback, code_ok(), msg_kill());
{error, lib_not_found} ->
msg(Feedback, code_lib_not_found(), err_lib());
{error, node_not_found} ->
msg(Feedback, code_node_not_found(), err_node())
end;
run(Feedback, status) ->
%%for development
add_cwd(),
case getstatus() of
daemon_not_found ->
msg(Feedback, code_daemon_found(), err_daemon());
{pid, Pid} ->
msg(Feedback, code_daemon_found(), msg_pid(), Pid);
{error, lib_not_found} ->
msg(Feedback, code_lib_not_found(), err_lib());
{error, node_not_found} ->
msg(Feedback, code_node_not_found(), err_node())
end.
add_cwd() ->
{ok,Cwd}=file:get_cwd(),
Cp=Cwd++"/ebin",
code:add_pathsa([Cp]).
getstatus() ->
try
Status=rpc(status),
case Status of
rpcerror ->
daemon_not_found;
{pid, Pid} ->
{pid, Pid}
end
catch
error:undef ->
{error, lib_not_found};
_X:_Y ->
{error, node_not_found}
end.
msg(Feedback, Code, Msg) ->
case Feedback of
verbose ->
io:format("etrx_control: ~s~n", [Msg]);
_ ->
ok
end,
halt(Code).
msg(Feedback, Code, Msg1, Msg2) ->
msg(Feedback, Code, Msg1++Msg2).
%%%%%%%%%%%%%%
%% RPC related
%%%%%%%%%%%%%%
rpc(Command) ->
case dorpc(Command) of
rpcerror ->
daemon_not_found;
Response ->
Response
end.
dorpc(Message) ->
Node=tools:make_node(transmission),
case rpc:call(Node, transmission_daemon, api, [Message], 2000) of
{badrpc, _Reason} ->
rpcerror;
Other ->
Other
end.
/**
* Code Syntax Highlighter.
* Version 1.5.2
* Copyright (C) 2004-2008 Alex Gorbatchev
* http://www.dreamprojections.com/syntaxhighlighter/
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, version 3 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see http://www.gnu.org/licenses/.
*/
/*
* Erlang syntax contributed by Jean-Lou Dupont http://www.jldupont.com/
* file: shBrushErlang.js
*/
dp.sh.Brushes.Erlang = function()
{
// According to: http://erlang.org/doc/reference_manual/introduction.html#1.5
var keywords = 'after and andalso band begin bnot bor bsl bsr bxor '+
'case catch cond div end fun if let not of or orelse '+
'query receive rem try when xor'+
// additional
' module export import define';
this.regexList = [
{ regex: new RegExp("[A-Z][A-Za-z0-9_]+", 'g'), css: 'vars' },
{ regex: new RegExp("\\%.+", 'gm'), css: 'comment' },
{ regex: new RegExp("\\?[A-Za-z0-9_]+", 'g'), css: 'preprocessor' },
{ regex: new RegExp("[a-z0-9_]+:[a-z0-9_]+", 'g'), css: 'mod_func' },
{ regex: new RegExp('"(?!")(?:\\.|\\\\\\"|[^\\""\\n\\r])*"', 'gm'), css: 'string' },
{ regex: new RegExp("'(?!')(?:\\.|(\\\\\\')|[^\\''\\n\\r])*'", 'gm'), css: 'string' },
{ regex: new RegExp(this.GetKeywords(keywords), 'gm'), css: 'keyword' },
];
this.CssClass = 'dp-erl';
this.Style = '.dp-erl .vars { color: rgb(184,134,11); }' +
'.dp-erl .mod_func { color: #CC00FF; }';
};
dp.sh.Brushes.Erlang.prototype = new dp.sh.Highlighter();
dp.sh.Brushes.Erlang.Aliases = ['erl', 'erlang'];
%% Author: Jean-Lou Dupont
%% Created: 2009-06-19
%% Description: Phidget InterfaceKit driver
%%
%% MESSAGES GENERATED:
%% ===================
%% {phidgeterror, {{Serial, Code, String}, date(), time(), now() }}
%% {device, {{Serial,Type,State, Version,Name,Label}, date(), time(), now() }}
%% {din, {{Serial, Index, Value}, date(), time(), now() }}
%% {dout, {{Serial, Index, Value}, date(), time(), now() }}
%% {sout, {{Serial, Index, Value}, date(), time(), now() }}
%%
%%
%% SUBSCRIPTIONS:
%% ==============
-module(ifk).
%%
%% MACROS
%%
-define(DRV_IFK_DEBUG, "pem_drv_ifk_debug").
-define(DRV_IFK, "pem_drv_ifk").
-define(SUBS, [phidgetdevice]).
%%
%% Exported Functions
%%
-export([
start_link/0,
start_link/1,
stop/0
]).
-export([
loop/0,
loop_handler/1,
handle_phidgetdevice/2,
filter_device/4,
handle_ifk/3,
handle_active/2,
handle_active/4,
handle_inactive/2,
handle_inactive/4,
ifk_drv/2,
send_to_reflector/1,
handle_crashed_driver/1,
clean_driver/1
]).
%% =============
%% API Functions
%% =============
start_link() ->
start_link([]).
start_link(Args) ->
{debug, Debug}=base:kfind(debug, Args,false),
DrvPath = base:pole(Debug, true, false, ?DRV_IFK_DEBUG, ?DRV_IFK),
LD = [{driver_path, DrvPath}],
NArgs = lists:append(Args, LD),
base:ilog(?MODULE, "start_link: Args[~p]~n",[NArgs]),
Pid = spawn_link(?MODULE, loop, []),
register( ?MODULE, Pid ),
?MODULE ! {args, NArgs},
{ok, Pid}.
stop() ->
?MODULE ! stop.
%% =====================================================
%% MAIN LOOP
%% =====================================================
loop() ->
receive
%% Send the 'ready' signal
{args, Args} ->
put(args, Args),
{driver_path, DrvPath} = base:kfind(driver_path, Args),
put(driver_path, DrvPath),
switch:subscribe(?MODULE, ?SUBS);
%% Send the 'ready' signal
{switch, subscribed} ->
%%base:ilog(?MODULE, "subscribed~n",[]),
switch:publish(?MODULE, ready, self());
stop ->
base:ilog(?MODULE, "exiting~n", []),
exit(ok);
%%verify that it is an "InterfaceKit" device
{_From, phidgetdevice, {M, Ts}} ->
%%base:ilog(?MODULE,"received 'phidgetdevice'~n", []),
handle_phidgetdevice(M, Ts);
{driver, Serial, Port, Pid} ->
base:ilog(?MODULE,"received driver info, Serial[~p] Port[~p] Pid[~p]~n", [Serial, Port, Pid]),
put({port, Serial}, Port),
put({pid, Serial}, Pid),
put({serial, Port}, Serial);
{crashed, Port} ->
clean_driver(Port);
%%don't know what todo
Other ->
base:ilog(?MODULE,"received unknown msg: [~p]~n", [Other])
end,
?MODULE:loop().
clean_driver(undefined) ->
base:ilog(?MODULE, "clean_driver: received undefined", []);
clean_driver(Port) ->
Serial = get({serial, Port}),
base:ilog(?MODULE, "clean_driver: Serial[~p] Port[~p]~n", [Serial, Port]),
erase({port, Serial}),
erase({pid, Serial}),
erase({serial, Port}).
%% =====================
%% HANDLER
%% =====================
handle_phidgetdevice(Msg, Ts) ->
%error_logger:info_msg("~p: handle_phidgetdevice, Msg[~p]~n", [?MODULE, Msg]),
{Serial, Type, State} = Msg,
filter_device(Serial, Type, State, Ts).
% we just want the InterfaceKit devices!
filter_device(Serial, Type, State, Ts) ->
case Type of
"PhidgetInterfaceKit" ->
handle_ifk(Serial, State,Ts);
_ ->
notifk
end.
%% Spawn 1 driver for each InterfaceKit device in "active" state
%% and get rid of detached device(s)
handle_ifk(Serial, inactive, Ts) ->
handle_inactive(Serial, Ts),
ok;
handle_ifk(Serial, active, Ts) ->
%error_logger:info_msg("~p: handle_ifk: Serial[~p] active~n", [?MODULE, Serial]),
handle_active(Serial, Ts),
ok;
handle_ifk(Serial, State, _) ->
base:elog(?MODULE, "handle_ifk: Serial[~p] INVALID STATE[~p]~n", [Serial, State]),
ok.
%% Open the driver if not already done
handle_active(Serial, Ts) ->
Port = get({port, Serial}),
Pid = get({pid, Serial}),
handle_active(Serial, Port, Pid, Ts).
handle_active(Serial, _, undefined, Ts) ->
handle_active(Serial, undefined, invalid, Ts);
% not sure this one is required
handle_active(Serial, undefined, undefined, Ts) ->
handle_active(Serial, undefined, invalid, Ts);
% Not active... yet
handle_active(Serial, undefined, invalid, _Ts) ->
DriverPath = get(driver_path),
%%error_logger:info_msg("~p: handle_active: DriverPath[~p]~n", [?MODULE, DriverPath]),
Pid = spawn(?MODULE, ifk_drv, [DriverPath, Serial]),
base:ilog(?MODULE, "handle_active: Serial[~p] Pid[~p]~n", [Serial, Pid]),
ok;
% Is it really active?
handle_active(Serial, _Port, Pid, Ts) ->
Active = is_process_alive(Pid),
case Active of
true ->
ok;
false ->
% clean-up required!
erase({pid, Serial}),
erase({port, Serial}),
handle_active(Serial, undefined, undefined, Ts)
end.
%% Close the driver if still active
handle_inactive(Serial, Ts) ->
Port = get({port, Serial}),
Pid = get({pid, Serial}),
handle_inactive(Serial, Port, Pid, Ts),
ok.
%not even defined it seems... nothing much to do
handle_inactive(_Serial, undefined, _, _) ->
ok;
handle_inactive(_Serial, _, undefined, _) ->
ok;
handle_inactive(Serial, Port, Pid, _Ts) ->
Active = is_process_alive(Pid),
case Active of
true ->
erlang:port_close(Port),
erlang:exit(Pid, kill),
erase({port, Serial}),
erase({pid, Serial}),
ok;
false ->
ok
end,
ok.
ifk_drv(ExtPrg, Serial) ->
%%error_logger:info_msg("~p:ifk_drv: Serial[~p] Pid[~p]~n",[?MODULE, Serial, self()]),
process_flag(trap_exit, true),
Param = erlang:integer_to_list(Serial),
Port = open_port({spawn, ExtPrg++" "++Param}, [{packet, 2}, binary, exit_status]),
error_logger:info_msg("~p: ifk_drv: Serial[~p] Port[~p] Pid[~p]~n",[?MODULE, Serial, Port, self()]),
put({port, Serial}, Port),
put({serial, Port}, Serial),
% signal back some useful mapping
?MODULE ! {driver, Serial, Port, self()},
loop_handler(Port).
%% =====================
%% IFK DRIVER loop
%% =====================
loop_handler(Port) ->
receive
{Port, {exit_status, _}} ->
base:elog(?MODULE, "loop_handler: an ifk driver exited/could not load~n", []),
handle_crashed_driver(Port),
exit(crashed);
{Port, {data, Data}} ->
Decoded = binary_to_term(Data),
%%base:ilog(?MODULE, "loop_handler: decoded msg[~p]~n", [Decoded]),
send_to_reflector(Decoded);
Msg ->
base:ilog(?MODULE,"loop_handler: msg[~p]~n", [Msg])
end,
loop_handler(Port).
send_to_reflector(Decoded) ->
{Msgtype, Msg} = Decoded,
M = {Msg, {date(), time(), now()}},
switch:publish(?MODULE, Msgtype, M).
%% =======================
%% CRASHED DRIVER RECOVERY
%% =======================
handle_crashed_driver(Port) ->
error_logger:warning_msg("~p: handle_crashed_driver: Port[~p] Pid[~p]~n", [?MODULE, Port, self()]),
?MODULE ! {crashed, Port}.
I got my LiveID invitation code 2days ago so I decided to invest 15minutes evaluating Azure. I am already pretty familiar with Google AppEngine having developed my own Web site on it but since I am striving to be "technology agnostic", I needed to investigate Microsoft Azure PaaS.
I invite anybody wishing to share their knowledge of the Cloud Computing market to edit (click the MindMeister image on the bottom righthand side of the map or here) the following wikimap:
I was digging through old backups just recently and I decided to make some .PST files more productive ( e.g. searchable ). I could have opted for Google Desktop ( I think ) to sift through those backups but I instead followed the GMAIL road since I am in the process of trying to convince my wife to move completly to GMAIL from Outlook.
I bought myself a DLINK DNS-323 (hardware revision B1) NAS unit. I fitted it with 2 Western Digital WD10EADS 1TB "Green Caviar" hard drives.
Through my daytime work, I use online tools a lot ( e.g. Gliffy, MindMeister ) so one could say I am confident about conducting work online. Sometimes though I feel I need a safety net and this is why I like to use my moonlight time to calm my qualms about the possibility of loosing my work.
Posts
All Comments
