Ignite Your Sites with revIgniter

[Editors note] This month we are celebrating the relaunch of our hosting service as LiveCode Hosting. With the spotlight on LiveCode Server I asked Ralf Bitter if he would like to write a bit about his excellent LC Server Framework, revIgniter.

Why revIgniter?

It was 2009 when the On-Rev web hosting service was introduced, long before the LiveCode Server engine was available to be installed on arbitrary web servers. Back then early adopters like me were thrilled and eager to learn about the new possibilities enabled by “a new variant of the existing technology that allows you to mix Revolution code with HTML content on the same page much in the same way as PHP”¹. There was a vibrant community dedicated to server-side scripting at the forums which were rapidly flooded with lots of code samples all mixing LiveCode (formerly Revolution) code with HTML or even additionally with CSS and JavaScript.

And this leads to the first possible answer to the headline question – “Why revIgniter”?

Why did I create revIgniter?

At that time I had a lot of fun taking the first steps in writing LiveCode code for the web, but I had a strong feeling that mixing markup and code might not be the best approach to write reasonably sophisticated programs for a web server. I had a feeling that there was missing a best practice solution to avoid redundancy, to provide a logical structure to access reusable code and to separate logic and presentation, especially for comprehensive multi-page projects.

The introduction of the include and require commands added in June, 2009 which allowed script files other than the main script to be parsed and executed, in combination with the merge function, opened the door and was the key to separating presentation from LiveCode scripting.

I started to think about building something like a framework to achieve the goals I had in mind but I knew I would not need to reinvent the wheel regarding a viable concept. As LiveCode server-side scripting has been modeled very strongly after PHP I just took a look over the PHP fence where I found a lean yet very impressive and absolutely compelling framework called CodeIgniter by Ellislab, Inc. I chose this as the pattern for a LiveCode web application framework to make it even more fun to write LiveCode code for a web server.

Obstacles and challenges

At first glance one might think translating PHP to LiveCode should be pretty straight forward. This may be the case for isolated functions but in my case I had to have a fairly thorough understanding of the overall structure of the PHP framework before I could even think about writing the first line of LiveCode code, primarily because of the different programming principles of PHP being an object-oriented programming language adhering to classes, objects, inheritance etc. Furthermore I was faced with PHP runtime configuration functions like error_reporting, display_errors, error_log etc., for which there are no equivalent counterparts in LiveCode. The same applies to built-in functions in PHP like for example addcslashes, preg_replace_callback, wordwrap, trim etc. This means that I had to be prepared to write lots of code from scratch without having any PHP prototype. That said, despite all the hurdles, at least for the first release I tried to adopt the whole concept as closely as possible to the one of CodeIgniter, so that those familiar with CodeIgniter would feel pretty fast at home using revIgniter.

Now to meaning number two of the question.

Why use revIgniter?

One could ask: why not use CodeIgniter or any other framework built using PHP? The answer should be clear: LiveCode is a multi-platform developing tool. It is that simple. As I am using LiveCode anyway to deploy programs to other platforms using code which is reusable for the web too, why should I dive into PHP or any other server-side scripting language if I don’t have to? But what’s the deal with revIgniter?

revIgniter helps to keep a project structured and focused. As mentioned above it helps to separate your scripts from presentation to avoid unnecessarily convoluted, cluttered code and hence to keep code maintainable. It speeds up development and minimizes the amount of code you are required to write by providing libraries for frequently needed tasks. To illustrate what all this means let’s adopt a scenario where there is a database query to dynamically populate a HTML table:

The code in “myModel.lc”:

# THE DATABASE QUERY  
function dataFromModel pTable  
    return rigDBget(pTable)  
end dataFromModel

# THE HTML TABLE TEMPLATE  
function myTableTemplate  
    put "<table border=" & rigQ("0") && "cellpadding=" & rigQ("4") && "cellspacing=" & rigQ("0") && "class=" & rigQ("mytable") & ">" into tMyTemplate["tableOpen"]  
    put "<tr class=" & rigQ("myRow") & ">" into tMyTemplate["rowStart"]  
    put "<tr class=" & rigQ("myAltRow") & ">" into tMyTemplate["rowAltStart"]

    return tMyTemplate  
end myTableTemplate

The code in controller “myController.lc”:

command index  
    # GET URI SEGMENT  
    put rigFetchRsegment(2) into tDBtable

    # GET DATA FROM DATABASE  
    put dataFromModel(tDBtable) into tQuery  
    put tQuery["resultarray"] into tResult

    # # BUILD TABLE  
    # HEADING  
    rigSetTableHeading tQuery["fieldnames"], TRUE

    # FETCH TABLE TEMPLATE FROM MODEL  
    rigSetTableTemplate myTableTemplate()

    # TABLE GENERATION  
    put rigGenerateTable(tResult) into gData["myDynamicData"]  
    #

    # LOAD MARKUP  
    get rigLoadView("myView")  
end index

Now to display the data simply add gData[“myDynamicData”] to markup in another file (the view “myView.lc”) like:

. . .  
<div><p>[[gData["myDynamicData"] ]]</p></div>  
. . .

Who and why – case studies

Alex Tweedly builds web sites for friends and local community / charity organizations. He developed websites using a slowly evolving set of “template” scripts of varying complexity, before he found revIgniter. Since then he has used revIgniter for all the sites (except for a brief foray into WordPress) like for example for kilmelford.com. The reasons he uses revIgniter are (citing Alex):

Mostly because there is just so much fully functioning, fully debugged library/framework/helper code to handle all the hard work.

Because it’s so much better documented than my various home-grown schemes.
It comes with great example auth.lc on which I can build authentication / member login, etc. (which I would otherwise struggle with, or get it wrong and leave vulnerabilities).

Dave Kilroy has developed various sites using revIgniter including a pricing and invoicing webapp and a revigniter ‘backend’ website members.plymsocent.org.uk associated with a wordpress website plymsocent.org.uk. Citing Dave:

A wordpress site is great but it doesn’t allow you to do so much – unless you are prepared to a) spend a long time learning their framework and b) possess php skills (or spend more time learning php).

He uses the revigniter website to let members edit their profiles and also to give committee members various tools to manage the Network. The site includes a “code bridge” between WordPress and a .lc file that updates the database the revigniter site connects to each time a transaction is made on the main WordPress site.

Martin Blackman uses revIgniter for some engineering calculations.
See xtrados.com/app/index.lc/PGML.

Martin Koob used revIgniter to create the backend API for a cloud based Mac OS app developed with LiveCode which streamlines the process of recording student performance on video and then marking that performance using annotations at time points on the video. The entire backend consists of the API, revIgniter, LiveCode Server and a WordPress part which serves as a means to handle user authentication, promotion, signing up, billing, managing the user’s account and providing some documentation.

[Editors Note] We love revIgniter here at LiveCode. Why not go and check it out for yourself, and maybe install it on your LiveCode Hosting website?