CGI FOR LCD SMARTIE 0.3-alpha

CGI for LCD Smartie is a plugin designed to be a fast gateway between LCD Smartie (lcdsmartie.sourceforge.net) and language interpreters such as PHP, Ruby or Python, making it easier to gather information to show on the display without the need to develop complex plugins.

DOWNLOAD

Latest release is cgi4lcd-0.3-alpha2

HOW IT WORKS?

CGI4LCD has a queue of commands. These commands are injected when the proper call to $dll(cgi,...) is made. At a specified time interval a command is executed and its response is stored. When LCD Smartie asks CGI4LCD for a previously sent command, the plugin sends back the cached response instead of executing the interpreter again. Also, there is a timeout value that dictates the moment of removal of a command if it is not being requested anymore.

WHEN IT WILL BE USEFUL?

• When you want to show data gathered from databases or internet applications
• When you want to develop that in a short timespan, using your preferred programming language.
• When you don't have patience to build complex plugins using C++, Delphi or VB.
• When you are really not interested in worrying about pointers, variable types, compilation and other cumbersome constraints that strongly typed languages has to bother you.
• When the time comes and CGI4LCD is dominating the market share of all other plugins so everyone starts developing scripts for fun and non-profit and someone creates something useful to you.

WHEN IT WILL NOT BE USEFUL?

If you're happy and pleased using the other plugins.
Basically, for everything that demands fast or realtime data displaying, like graph bars or realtime system monitoring.
Believe me, the minimum time interval that LCD Smartie is allowed to get data from the plugin is 1 second and even if it was smaller, the default time interval to re-execute an interpreter is 15 seconds. Oh, are you thinking about decreasing everything to 100 ms? Only if you have a good machine configuration to support thousands of processes doing the same thing.
Really, don't try it. I beg you to use C++.

INSTALLING

• Make sure you have .Net Framework 3.5 microsoft.com.
• Make sure you have LCD Smartie 5.4 or 5.4.2.92b (or grab it from lcdsmartie.sourceforge.net).
• Grab the latest version of CGI4LCD from downloads.
• Copy plugins and scripts directory to your LCD Smartie directory.
• Boost >= 1.47 (boost.org / pre-compiled: boostpro.com) if you want to have some fun compiling the project by yourself.

CONFIGURING

The configuration is stored in cgi4lcd.ini (available in scripts directory).

The first section is [cgi4lcd]. It has the following attributes:

• interval (numeric, seconds)
  Defines how often a command it will be executed

• timeout (numeric, seconds)
  Defines how long after the command is not requested anymore by Smartie to be removed from the queue

• refresh (numeric, seconds)
  Value to tell LCD Smartie how often it will request data from plugin

• default_extension (text)
  The default file extension to be considered by the plugin if not specified in the filename passed to $dll

• max_threads (numeric)
  The maximum number of commands that can be run simultaneously

The subsequent sections are named with the common file extension of the language. They have the following attributes:

• language (text)
  Language name relative to the extension. Not used right now

• interpreter (text)
  Absolute path to the language interpreter

• command (text)
  The command line to execute the script. It has variables that are replaced when the plugin stores a command. They are:

  * %scripts_path%  

The absolute path to [LCD Smartie path]\scripts directory

  * %routers_path%  

The absolute path to [LCD Smartie path]\scripts\routers directory

  * %script%  

The absolute path to [LCD Smartie path]\scripts*[script name]*

  * %params%  

Function name or function name and parameters specified in the last argument passed to $dll

  * %interpreter%  

The path specified in the property interpreter

• version
  Command line parameters to get the interpreter version

CGI4LCD comes with the basic settings to run PHP, Ruby, Python, Lua and Perl scripts. You must only change the interpreter path and it will be ready to use.

USING

function1 - Places the command in the queue and executes interpreter

• filename - mandatory. it must exist in scripts directory.
  The extension is optional. If not passed, the plugin will use the default extension set in the section [cgi4lcd] of the configuration file.
• function (optional) and arguments (separated by semicolons), also optional.

Syntax: $dll(cgi,1,filename[.extension],[function[#arg1;arg2;...]])

There are three possible usages for code executing:

• Executing a script

Syntax: $dll(cgi,1,file[.ext],)

• Executing a function of a script without arguments

Syntax: $dll(cgi,1,file[.ext],function)

• Executing a function of a script with arguments

Syntax: $dll(cgi,1,file[.ext],function#arg1;arg2;argX)

function2 - Places the command in the queue without executing it

• The same arguments of function1

function3 - Executes the command without placing it in a queue

• The same arguments of function1

function4 - Gathers interpreter version by extension

• extension - optional. If empty, will use the default extension

Syntax: $dll(cgi,3,[extension],)

function20 - Credits

• No arguments required

WRITING SCRIPTS

First of all, you'll need to know what is a router: a piece of code responsible for calling a function, retrieving its result and printing to the screen, so the plugin can grab and relay it to Smartie. Routers are optional if your script outputs data directly to screen but mandatory if you want to group functions in a file.

The script must be saved in scripts directory and has the following structure:

# include router
# declare functions
main(); # Execute router

or

[write code that outputs directly to the screen]

The scripts/tests directory is full of test.[extension] files that describes the basics of writing functions. Try it yourself:

$dll(cgi,1,test,hello) -> Hello, world!
$dll(cgi,1,test,hi#Mendel) -> Hi, Mendel
$dll(cgi,1,test,do_some_math#1;2;3) -> 5

BUNDLED LANGUAGES

When I say "bundled", I mean it already has routers and basic configuration for the mentioned languages. You still need to download the interpreters from the internet to use their languages.

PHP · PYTHON · RUBY · PERL · LUA · JAVASCRIPT

Or... Write your own. I'll be glad to add your contribution to the project.

LANGUAGE SPECIFICS

PHP

To give some boost to PHP interpreter startup, write a crafted php.ini. This must a stripped version that doesn't make PHP load too many extensions. Add the -c parameter to command template in [php] section. e.g.:

command="-d auto_prepend_file='%routers_path%\php.php' -c '%scripts_path%\php.ini' '%script%' '%params%'"

Python

While PHP (e.g.) allows to pass a file from the command line to be included in the called script, Python doesn't (or, at least, I don't know how to). When writing a Python script, put on the first line:

from routers import main

Lua

The interpreter can't load a module by its full path using the "-l" command line parameter. Copy [LCD Smartie installation dir]\scripts\router\lua.lua to [Lua installation dir]\lua before using CGI4LCD with Lua.

Perl

The interpreter can't load a module by its full path. Instead, the path to routers directory is passed using "-I" parameter. When writing a Perl script, put on the first line:

require("pl.pl")

JavaScript (using node.js)

The interpreter doesn't provide a way to specify a path or a module to be loaded before the script to be run, so, put on the first line of your script:

require("routers/js.js")

ISSUES

• [Your complaint here]

TODO

• Provide better support to Unicode strings.
• Rewrite almost every function or method to use char* instead of strings.
• Allow configuration of command interval/timeout per-language, per-script and per-function.
• [Your suggestion here]

FINALLY

• Official website of LCD Smartie: lcdsmartie.org
• Official CGI4LCD thread at LCD Smartie forums: forums.lcdsmartie.org
• Contact the author: [email protected]