Midgard's Component Framework Henri Bergius henri.bergius@iki.fi Nemein Oy 2004-09-29 2004-10-01 OSCOM 4 Zurich, Switzerland Open Source Content Management, Midgard 2004-09-30 Copyright 2003 Henri Bergius & Nemein Oy, Available under Creative Commons Attribution-ShareAlike

Introduction to the MidCOM component framework for Midgard CMS

What is Midgard?
  • Open Source Content Management System for managing information on the web
  • Started in 1998, released to public in May 1999
  • Active and diverse international developer community, participating in the OSCOM process
  • Thousands of deployments, including universities, NGOs, businesses and governmental organizations
  • Running on the LAMP (Linux, Apache, MySQL and PHP) architecture
  • Free software licensing: GNU GPL and LGPL
  • PHP extension and Apache module
 Some features in Midgard
  • All data access goes through Midgard's C library; performance and security
  • Support for multi-organization hosting (Sitegroups)
  • Internationalization: translation tools and non-western characters (UTF-8) support
  • Fully web based authoring and administrative tools with WYSIWYG editing
  • Separation of content, layout and structure. Powerful PHP based style engine
  • Clean, file-like URLs (for search engine support and easier pronounciation)
  • Multiple authentication methods: Midgard DB, PAM and NTLM
 Midgard API example 
<?php
// Authenticate with Midgard
mgd_auth_midgard("username","password",0);
$midgard = mgd_get_midgard();

// Instantiate a new article
$article = new MidgardArticle();
$article->title = "My new article";
$article->name = "my_article";      // Usually used in URLs
$article->author = $midgard->user;  // Reference to MidgardPerson
$article->topic = $mytopic;         // Reference to MidgardTopic
// Save it
if ($article->create()) {
  echo "Successfully created article";
} else {
  echo "Article creation failed, reason ".mgd_errstr();
}
?>
Introduction to MidCOM
  • Components are applications that provide a specific site feature, like news listings, event calendars or static content display
  • A component is specified for each folder (topic) of the site
  • MidCOM provides a standardized ways for configuration, layout templating and content structure definition (datamanager schemas)
  • The midcom-template package is the fastest way to set up a MidCOM based website
  • MidCOM is the default way of building websites with Midgard in version 1.6.0
  • Strict namespacing (Java-like) and coding standard (PEAR)
 MidCOM usage example
  • Browse the web site
  • Log in
  • Find a page that needs updating
  • Click "Edit page", make changes, save, view
  • Create new documents
  • Create new subfolders
 MidCOM templating engine
  • Extension of the standard Midgard templating engine
  • Style is split into elements
  • Simple syntax
    • &(object.property); = Echo property value
    • &(object.property:h); = Echo property value with HTML allowed
    • <(element)> = Include a style element
  • Embedded PHP is also allowed but discouraged
  • Style templates can be overridden on per-folder or per-folder tree basis (selection dialogue in "Edit folder")
 MidCOM configuration engine
  • Configuration is defined in PHP array syntax, key => value
  • Components provide a default configuration in _config snippetdir
  • Configuration can be overridden on per-key basis either for:
    • Per-organization basis (stored in sitegroup-config snippetdir)
    • Per-folder basis (stored as topic parameters)
  • Most components provide a datamanager-driven UI for changing per-folder configuration
 MidCOM datamanager
  • Data structure abstraction layer
  • Fields defined in a schema snippet (PHP array syntax)
  • Enables extension of MidgardObjects
  • Document creation, locking, saving and error handling
  • Version control (serialized to external RCS files)
  • Document editing form generation and handling:
    • Different widgets: text entry, WYSIWYG HTML, selection, image upload etc.
    • Field validation support
    • Structuring forms with fieldsets
 MidCOM datamanager schemas 
"default" => array (
    "name"        => "default",
    "description" => "News article",
    "fields"      => array ( // Define the form fields
        "name" => midcom_helper_datamanager_urlname_field(),
        "title" => array (
            "description" => "Title",
            "datatype"    => "text",
            "location"    => "title", 
            "required" => true,
        ),
        "content" => array (
            "description" => "Text",
            "datatype"    => "text",
            "location"    => "content",
            "widget"      => "html" // Use HTMLAREA
        ),
   ),
),
Future plans for MidCOM
  • MidCOM development is governed by the mRFC process
  • Moving the code from database to file system, PEAR packaging
  • Integrated indexing support (PLucene?)
  • Centralized workflow support (now handled by components)
  • Migration to PHP5
  • Midgard Site Wizard for quicker setting up of MidCOM sites
 Midgard resources