A brief overview of Drupal 7

By Robin Isard, Systems LibrarianAlgoma University

What I'm going to look at

Overview of Drupal 7 The module system How Drupal manages your data Case study – 2 years working with Drupal

What is drupal?

Content Management System Becoming more of a Content Management

Framework Created by Dries Buytaert, a Belgian computer

science student in 1998 3 major releases since then

Current major release is Drupal 7 As of 2011 approximately 630,000 subscribed users “A drop”

Architectural Overview

Essentially a LAMP stack Modular

Core Contributed Custom Themes

Business logic intensive

Core

Core modules Blogs Comments Aggregator (RDF,

RSS, Atom feeds) Forums Polls Taxonomy (tagging) Menu customization

Hierarchical ordering of content

Tracking system Statistics OpenID login Logging Theming system Update manager Trigger system

Drupal community

Contributed modules

Functionality and themes 9947 modules total 3929 compatible with Drupal 7

“Content”: 551 “File Management”: 90 “Administration”: 343 “Themes”: 298

IMCE

How modules work

A collection of php files designed to implement some find of functionality /sites/default/modules mymod.info mymod.install mymod.module

.info

name = Administration menu

description = "Provides a dropdown menu to most administrative tasks and other common destinations (to users with the proper permissions)."

package = Administration

; Purposively added for feature development.

version = 7.x-3.x-dev

core = 7.x

project = admin_menu

.install/**

* @file

* Install, update, and uninstall functions for the admin menu module.

*/

/**

* Implements hook_schema().

*/

function admin_menu_schema() {

$schema['cache_admin_menu'] = drupal_get_schema_unprocessed('system', 'cache');

$schema['cache_admin_menu']['description'] = 'Cache table for Administration menu to store client-side caching hashes.';

return $schema;

}

.module

Hook system Php function Defined input and output Allows you to implement a certain behavior at a

certain point in drupal core

Hooks

<moudle_name>_<hook_name>() hook_user_load() mymod_user_load()

342 available hooks hook_comment_load hook_cron hook_css_alter hook_field_validate

Example/**

* Implements hook_help().

*/

function admin_menu_help($path, $arg) {

switch ($path) {

case 'admin/settings/admin_menu':

return t('The administration menu module provides a dropdown

menu arranged for one- or two-click access to most administrative

Tasks … the menu.');

case 'admin/help#admin_menu':

$output = '';

$output .= '<p>' . t('The administration menu module provides a dropdown menu arranged for one- or two-click ....');

APIs

Module system (Drupal hooks) Database abstraction layer (Schema API) Menu system Form generation File upload system Field API Search system Node access system Theme system

Data access and storage

Data management

By default a LAMP stack Other database options available with more or less

support Drupal 7 has a rewritten database abstraction

layer PostgreSQL now a first class member of the

community MongoDB

Essentially uses Object-relational mapping

APIs

Entity (core) Entity API

Schema API

Important data management concepts

Entities Users Taxonomy terms Comments Nodes

Fields Entity + Fields = Bundles

Bundle - Example

news_item (a node entity)

+ Date (field) Subject (field)

= “news_item bundle”

Key entity hooks hook_entity_info()

Entity (core) hook_schema()

Schema API

Entity API entity_create() entity_save() entity_delete() entity_view() entity_access().

function user_entity_info() {

$return = array(

'user' => array(

'label' => t('User'),

'controller class' => 'UserController',

'base table' => 'users',

'uri callback' => 'user_uri',

'label callback' => 'format_username',

'fieldable' => TRUE,

'entity keys' => array(

'id' => 'uid',

),

'

hook_entity_info()

hook_schema()function user_schema() {

$schema['authmap'] = array(

'description' => 'Stores distributed authentication mapping.',

'fields' => array(

'aid' => array(

'description' => 'Primary Key: Unique authmap ID.',

'type' => 'serial',

'unsigned' => TRUE,

'not null' => TRUE,

),

'uid' => array(

'type' => 'int',

'not null' => TRUE,

'default' => 0,

'description' => "User's {users}.uid.",

hook_schema()

Supports primary and foreign keys Supports indexes Field lengths

Precision Signed / unsigned

Data storage example

Data storage example public | node |

table |

public | field_data_field_db_access_link | table |

public | field_data_field_db_build_name | table |

public | field_data_field_db_description | table |

public | field_data_field_db_ezp_note | table |

public | field_data_field_db_ezp_test | table |

public | field_data_field_db_sfx_name | table |

public | field_data_field_db_url | table |

Data storage exampleTABLE: node

nid | 164

vid | 164

type | db

language | und

title | Women Writers' Project

uid | 1

status | 1

created | 1317243764

changed | 1332779771

comment | 1

promote | 0

sticky | 0

tnid | 0

translate | 0

TABLE: field_data_field_db_url

entity_type | node

bundle | db

deleted | 0

entity_id | 164

revision_id | 164

language | und

delta | 0

field_db_url_value | http://.... field_db_url_format |

Viewing your data

Views module Still a contributed module Essentially a report writer Complicated

Database API

An example: Algoma University's Archive

Algoma University Archive

Over 25,000 images and documents 3 TB of data on scattered hard drives Most of the data important for legal purposes Index housed in InMagic-DBtextworks

“Relational like” ASP driven No social media aspects No means to display the content in an engaging

way

Questions we asked about a new CMS

Service integration Is there documentation? Is there an API?

Does it support data exchange protocols? JSON XML RDP

Questions we asked about a new CMS

Data access and storage How does it store data? Does it have a CRUD layer? Can I get my data out of it in standard formats?

CSV XML

What options are there for non-sql data?

Migration

2010 project started to update the archive We chose Drupal because

It seemed to answer the questions listed above of it's very large user community recommendations from peers it's ability to integrate with enterprise technologies

like Fedora Commons and Solr It's social media abilities

Phase 1

Get the data out of InMagic and into Drupal Took nearly 4 months Process

Dump the data out of InMagic as CSV files Import into PostgreSQL Use SQL to clean up and format the data Use “migration module” to import the cleaned up

tables into Drupal

Phase 2

Use Drupal's extensibility to ability to meet archivist needs for the archive

Problems with contirb Postgres Bad code Malfunctioning modules Dates

Unix time stamp no good for archives

Phase 3 – in planning

Migrate to drupal 7 Needs to be done

No back-porting Drupal is now smarter about databases – which is a

problem

Lessons learned - modules Drupal runs the show Always interact with Drupal via a module Stay as close to core as possible Is this the best possible module for the job? Put time into choosing modules

When was the last commit? Do you understand the code yourself? Is there a plan to upgrade it?

Read the code for you modules You should be able to fix it yourself

Lessons learned - database

Drupal doesn't really like relational databases Do you know what a given module will do to the

DB? Categories module

Does it use MySQL specific statements? Use Fields and Views as much as possible Always interact with the DB via a module

The possibilities

Database layer can be rewritten All kinds of data stores theoretically possible Can be conceptualized as simply a user interface

for different kinds of data stores

Discovery Solr integration Islandora Web services