WORDPRESS MULTISITE ENVIRONMENT 

GREETINGS EARTHLINGS @acodesmith | acodesmith.com | Adam Smith 

WORDPRESS AS A SINGLE BLOG 

SINGLE BLOG ★User roles are set for the entire site. ★One theme is activated at a time. ★Plugins are managed on a case by case basis. ★All tables share the same prefix. 
 For example: wp_posts 

HOW WORDPRESS WORKS AS A MULTISITE 

A queen bees pheromones affects social behavior, maintenance of the hive, swarming, and mating behavior. 

MULTISITE ★User roles are set on a site by site basis. ★Themes are approved by the site admin then activated per site. ★Plugins can either be Network Activated or on a site by site basis. ★Each site has it’s own set of tables prefixed by the site ID.
 For example wp_2_posts ★Site IDs are auto incremented primary keys in the wp_blogs table 

USER ROLES ★The super admin can access each different site dashboard. ★The super admin can approve which themes can be activated. ★The super admin can Network Activate plugins. ★The super admin can create a new site and add users to that site. ★A user for one site can only access their site dashboard. 

THEMES ★The super admin approves which themes can be used by other sites. ★Each site selects a theme. ★All themes live in the themes folder. ★Multiple sites can use the same theme. ★Make changes to one theme, updates all site using that theme. 

PLUGINS ★The super admin can Network Active a plugin. ★A Network Activated plugin is used by all sites and can not be excluded by one site. ★A single site can activate a plugin, just like normal, for that site only. ★Plugins which generate custom tables use the site prefix.
 For example:
 wp_2_woocommerce_sessions 

TABLES ★WordPress creates a new table called wp_blogs ★The blog_id field in wp_blogs is used as a prefix for each site.
 For example: blog_id 2 is used to create wp_2_posts ★WordPress creates new post, postmeta, taxonomy, terms, options, comments, etc.. ★Each site does NOT get a new users table. All sites share a common wp_users table. 

TURN ANY WORDPRESS SITE INTO A MULTISITE 

/* Multisite */ define( 'WP_ALLOW_MULTISITE', true ); 

DOUBLE CHECK AND BACK UP EVERYTHING ★ Installation and Server Requirements ★ mod_rewrite must be enabled. ★ site can’t be hosted on an IP ★ site can’t be hosted on a special port; mysite.com:8080 ★ site can’t be hosted on a localhost url, must use vhost for local install. ★ Backup all tables! ★ Deactivate all your plugins! ★ Subdomain install can’t be ran out of a subfolder, only the root;
 mysite.com/wordpress-installed-here/ 
 mysite.com/wordpress-installed-here/site2 

TALES OF WOE AND VICTORY 

WOE ★If the main site goes down they all go down. ★If one site is hacked all sites can be affected. ★One database password for all the sites. ★A bug in a plugin or a theme can affect multiple sites. 

VICTORY ★New features can be rolled out to all the sites at once. ★Backup one database! ★Fix a bug in one place, you fix a bug for multiple sites. ★Easier to support a large client base. 

BUILDING A MULTISITE PLUGIN 

FUNCTIONS FOR VALIDATING THE MAIN SITE FUNCTIONS FOR GETTING THE CURRENT SITE FUNCTIONS FOR SWITCHING TO ANOTHER SITE 

CHECK IF THE USER HAS ACCESS TO A CERTAIN SITE Could be used to show beta features to special users for certain blogs. 

GET DETAILS ABOUT A BLOG BASED ON THE BLOG_ID 

TABLE PREFIX ★Using the global $wpdb object to obtain the prefix.
 For example: $wpdb->prefix ★Use the prefix when building custom tables. ★Use the prefix when writing raw SQL queries. 

HOOK FIRES WHEN A NEW SITE IS CREATED HOOK FIRES WHEN A SITE IS REMOVED HOOK FIRE WHEN A SITE IS ARCHIVED https://core.trac.wordpress.org/browser/tags/4.7.3/src/wp-admin/includes/ms.php 

WHY MULTISITE 

WHY MULTISITE ★Software as a service platform ★Managing multiple clients in one controlled space ★Repeatable service model ★Whitelabel products 

QUICK DEMO AND QUESTIONS