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Konstrukt::Doc::About - About the Konstrukt framework and its design


This framework aims (beside other goals) for separation of presentation, logic and content.

The presentation is basically accomplished with a very powerful templating system, which allows fine grained modularization of the presentation components (templates can be nested as deep as you want) and has an easy to use interface, that any non-programmer will understand.

The logic is encapsulated in plugins, which can be integrated seamlessly into the websites using a simple tag-interface. You can develop your own plugins easily and also use the existing plugins for your own ones through the perl-interface of the existing plugins. The Konstrukt core will do all the nasty donkeywork for you, so you can concentrate on the logic of your application.

The content for each application-plugin is stored in a database using Perl DBI. The data backends for each plugin are implemented as a separate plugin, which can be exchanged easily, so the applications can adapt to various data stores. Static content (layout, static web pages, ...) will be stored in modular templates.

Your web pages will only describe what they contain, not how they are generated. They will be as simple as:

        <!-- use a template for the page layout, set the page title to "blog"
             and use the blog plugin as the content -->
        <& template src="/templates/layout.template" title="blog" &>
                <$ content $>
                        <& blog / &>
                <$ / $>
        <& / &>


There already exist several application plugins, which cover some common needs in developing a website:

  • A powerful templating system

  • Blog

  • Wiki

  • Calendar

  • Guestbook

  • Embedded Perl

  • and much more...

You may build rich web sites in an instant and have full control over the look and feel through the template system.

You may also nest (and thus combine) the tags/plugins into each other, which makes it a very powerful but still easy to use system.


This framework has these main goals:

1. Rapid development
2. Separation of code, content and layout
3. Reuse of code/markup
4. Clean code
5. Speed

These goals are accomplished by the following techniques:

1. Rapid development

As this framework supposes heavy use of templating, you'll usually never write markup twice. The templates can be easily nested into each other which allows for high modularity and reuse even at the markup level.

Additionally there already exists a wide range of plugins/applications, which offer commonly used functionality like blogs or wikis.

If you want to develop an application that's not yet covered by the supplied plugins, you can develop your own ones "easily" (ok, you cannot just hack away on it, you have to read a bit before). The framework supports your plugin development with an existing infrastructure of session and user management, debug facilities, settings handling and request/response-objects. So you don't have to do this nasty work.

Additionally this framework offers a neat auto-installation feature for the plugins. If the auto-installation is enabled and you use a plugin (for the first time), the database tables and templates for this plugin will be created automatically. No work for you! Nice, eh?

2. Separation of code, content and layout

The logic is implemented in the plugins (which will be used as tags from the markup). You won't write any markup in your plugins, instead your plugins pass all data to templates, which will display your data and allow the user to interact with your plugin.

Thus all markup (html, xhtml, xml, ...) will be inside the templates. The templates won't contain any code, unless it's only used for the presentation. The Konstrukt tag interface is used to glue the markup and plugins together.

The data/content is usually stored in a database, which will be accessed by the plugins. Static content will be placed in template files.

This principle allows for better maintainance and division of work. A programmer can focus on the code (plugins) and a web designer can focus on the markup (templates).

Of course it's also possible to embed perl code into the templates or print out markup from your plugin. But this is not recommended and avoided through the frameworks own plugins. The only accepted use for code inside the templates is to use it in complex presentations, where the template interface isn't powerful enough.

3. Reuse of code/markup

The logic is encapsulated in plugins, the markup in templates. These can be reused within the web site or over several different web sites. So generally you write once and use often (DRY - don't repeat yourself). This avoids redundancy and duplicate work.

4. Clean code

At first, the separation of code and markup will greatly improve the overall code quality.

But also internally there was a big focus on clean code. All code is written in object oriented perl with strong modularization. The code is heavily documented and commented (i'd guess a code:documentation ratio of about 1:1) and "obfuscated" code is avoided where possible. Very spare use of global variables, constant use of "strict" and "warnings" pragmas. Further development and enhancement should be easy.

5. Speed

There is a very smart chache mechanism used in this framework. The cache system will identify static parts of your web pages (static markup and plugins that don't generate dynamic content) and cache the document so that only the dynamic parts of a document will be executed on a request and not the whole document. All static documents of course will be served directly without any further processing. Additionally the atomic template components will be cached to speed up the use in all documents using them.

Caching is a basic concept within this framework with the goal not to calculate anything twice when it didn't change. The downside of this is, that a plugin developer hat to understand the caching system, when she/he wants to develop high-performance plugins. If speed is not that important or if your application type cannot profit ofthe caching system, there is also a simple plugin development interface where one doesn't have to care about caching.

The framework is designed to work in a mod_perl (version 1 and 2) environment which allows for further speed gains. But there are also interfaces for CGI and for the execution from the command line.


Copyright 2006 Thomas Wittek (mail at gedankenkonstrukt dot de). All rights reserved.

This document is free software. It is distributed under the same terms as Perl itself.


Next: Konstrukt::Doc::Installation, Konstrukt::Doc::Basics

Parent: Konstrukt::Doc

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