Justin Klein Keane Drupal Training Session 1 Introduction to Drupal

Justin Klein Keane Overview ● What is Drupal? ● Building blocks of Drupal ● Drupal terminology ● How Drupal works

Justin Klein Keane What is Drupal ● Open source content management system ● What is a CMS? ● Drupal is actually much more than a CMS – Web application framework

Justin Klein Keane PHP ● Drupal is written in PHP ● Web application scripting language ● Open source language sponsored by Zend ● PHP is actually written in C ● Easy to learn ● Great for rapid application development ● One of the more popular languages for web applications

Justin Klein Keane How PHP Works ● PHP is run by the web server ● PHP code embedded in web pages is compiled and interpreted when the page is requested ● Uncompiled code means portability and rapid refactoring ● PHP is truly dynamic – Even variable names can be dynamic ● Code can include other scripts or libraries

Justin Klein Keane Data Persistence ● Like most web applications Drupal needs to store data ● Data is in a database (MySQL) – Database means content changes happen in the database rather than in code or on files – Makes for easy portability and backup – Access via code, or directly at command line – SQL is a standard, popular, well understood language

Justin Klein Keane Drupal Hierarchy ● Drupal uses dynamic includes to load code ● What happens when there are conflicts? – Last loaded code is the one that runs ● Drupal uses this to allow developers and users to “extend” Drupal

Justin Klein Keane Composition of Drupal ● Drupal includes a common set of files used to “bootstrap” Drupal – Set up database connections, provide authentication, present output, etc. ● Drupal has additional modules – These are dynamically included depending on configuration – 33 modules are included in the Drupal core

Justin Klein Keane Running Drupal ● Every Drupal request goes to index.php, even if the URL looks like a different location ● Index.php does bootstrapping: – checks database for enabled modules – loads modules that are appropriate – checks permissions – queries database for content – applies theme – renders the page

Justin Klein Keane When things go bad ● When Drupal encounters a PHP fatal error: – White screen of death ● What has happened: – PHP hit an error that forced a stop to compilation – PHP logs the error in the web server logs – Potentially Drupal logs the error in the Drupal watchdog table – Execution dies silently without output

Justin Klein Keane Drupal filesystem structure /includes- Drupal core PHP files /misc- Various image and js files /modules- Core modules /profiles- Profile settings (own tree) /scripts- Maintenance non-web scripts /sites- Site definitions /themes- Core themes

Justin Klein Keane Top Level Files ● Several critical php files: cron.php- web interface for scheduled tasks index.php- everything flows through index.php install.php- installation file (remove) update.php- update install (for new modules) xmlrpc.php- provide remote procedures (opt.) ● Various other text files

Justin Klein Keane How to install Drupal ● You need a database and a web server with PHP already running ● Create a database for the Drupal site ● Download the Drupal code from Drupal.org ● Point web browser and Drupal root and the rest is automated

Justin Klein Keane Drupal terminology ● Drupal uses a lot of words that have very specific meaning: – Module – Theme – Block – Node – Menu

Justin Klein Keane Modules ● Modules can be installed in a number of locations – /modules – /sites/all/modules – /sites/default/modules – /profiles/profileName/modules ● Modules should be installed in: – /sites/all/modules

Justin Klein Keane What is a “module” ● Modular piece of code that extends Drupal ● Uses the Drupal API – Just a set of functions defined in the Drupal core (or other modules) ● Provide drop in functionality ● Can be enabled/disabled (in the database) ● Provide additional functionality without altering the Drupal core

Justin Klein Keane Built in Modules ● Aggregator ● Block ● Blog ● Blogapi ● Book ● Color ● Comment ● Contact ● Dblog ● Filter ● Forum ● Help ● Locale ● menu Node Openid Path Php Ping Poll Profile Search Statistics Syslog System Taxonomy Throttle Tracker, translation, trigger, update, upload and user

Justin Klein Keane Look and Feel ● Drupal takes a similar approach to display ● Display is a separate area of Drupal ● Many components of Drupal are defined in the “theme” ● Themes are comprised of HTML, CSS, PHP and imagery ● Themes utilize the same hierarchy as modules ● Theme files are called “templates”

Justin Klein Keane Advantage of Themes ● Themes follow a convention (standardization) ● Can easily be swapped out to quickly change or upgrade the look of a site ● Useful because theme developers need not necessarily be Drupal developers (or PHP programmers) ● Can provide powerful filters to screen output in Drupal

Justin Klein Keane Blocks ● Blocks are pieces of content placed in regions of Drupal pages ● Blocks are arbitrary pieces of content ● Usually the stuff that appears in sidebar, header and footer content ● Blocks can be content, forms, special lists, polls, or arbitrary HTML ● Themes define regions for blocks

Justin Klein Keane Nodes ● Drupal organizes most content around the concept of a “node” ● Nodes are just pieces of content ● Only a few things aren't nodes – users, groups, modules, and themes being the main ones ● Other stuff, from calendar events, to RSS feed items, to page content is a node

Justin Klein Keane How Nodes Work ● Nodes support versioning ● As a result node content is stored in the node_revisions table ● The Drupal “node” table only stores metadata about nodes ● Nodes can have various modules applied to them to adjust input and output handling

Justin Klein Keane Organizing Nodes ● There are all sorts of nodes, how do we keep them organized? ● Drupal supports a categorization of nodes that allows for various node “definitions” ● Content types allow Drupal users to define various fields for different types of nodes ● For instance, one node might include a URL, another a title ● Using “fields” specific to node types allows sorting and display (rather than having the data stuck in a node “body”)

Justin Klein Keane Content Types ● “Page” and “Story” are two default content types ● The titles are arbitrary ● Content types define input fields and how the content is displayed ● New content types can easily be created ● Content type creation should follow careful consideration of site architecture and purpose

Justin Klein Keane Taxonomy ● Taxonomy is another way to organize content ● Taxonomy are “tags” that are applied to content ● “Vocabularies” set up as taxonomies ● Vocabularies then contain terms ● Taxonomies can be extended and used for various rules in the Drupal back end ● Taxonomy can also be used for display purposes

Justin Klein Keane Menus ● Drupal menu system is also fairly arbitrary ● Display and positioning is controlled by themes ● Three default menus: – Navigation – Primary links – Secondary links

Justin Klein Keane Users and Groups ● Drupal allows users to create accounts ● Users are assigned to groups ● By default two groups are defined in Drupal – Authenticated User – Anonymous User

Justin Klein Keane Permissions ● Drupal utilizes a Role Based Access Control (RBAC) system ● Users are assigned to roles, roles receive permissions ● Permissions are set through the Drupal administrative interface ● Uid 1 user (created during install) has all permissions ● When in doubt: it's a permissions issue

Justin Klein Keane Default Drupal is Pretty Useless

Justin Klein Keane Got Drupal, now what? ● Drupal out of the box doesn't look like much ● Drupal is extremely flexible but requires a lot of configuration ● Changing Drupal after deployment is a pain, so you must plan carefully ● Drupal is a framework that doesn't make assumptions about use cases ● Drupal requires lots of tweaks to enable functionality the way you want it

Justin Klein Keane For next time: ● A walk through of Drupal installation ● Installing and enabling modules ● A walk through of module cod