Plug-in Manager

A plugin is a piece of code that answers an event. The Plug-in Manager cannot install or delete plugins; it enables and disables them, sets their access level, changes the order they run in, and edits their parameters.

Select Extensions → Plug-in Manager, or go to /administrator/index.php?option=com_plugins.

Three hundred and thirty-two plugins ship with the platform, and a manager touches perhaps five of them in a year. You come here to switch on a way of signing in, to turn off a tab on group pages that your hub does not use, to enable a spam detector after a wave of junk postings, or to work out which plugin is responsible for something appearing on a page. Nothing here needs routine attention.

This chapter covers state, access and order. A plugin's own parameters are covered in Plugins.

What this is not

It is not an installer. There is no New and no Delete, and there never will be on this screen: plugins arrive and leave with the code.

Disabling a plugin is also not a way to hide content. Turning off the plugin that supplies a tab removes the tab, not what is behind it; the records stay in the database and come back the moment the plugin is enabled again. That cuts both ways — it makes disabling safe to try, and it means disabling is not a way to make anything private.

How plugins work

Plugins live in core/plugins/, and a hub's own in app/plugins/, which takes precedence. Each plugin is a directory two levels down — plugins/<folder>/<name>/ — containing <name>.php and <name>.xml. The folder is the plugin's group, and it decides which events the plugin can answer.

When the platform reaches a point where extensions may contribute, it imports every enabled plugin in the relevant folder, in ordering order, and calls the matching method on each. A plugin in the authentication folder is asked to authenticate; one in content is given content to filter; one in cron is asked for scheduled jobs.

Several folders work differently: instead of filtering something, the plugin is a whole section of a page. Every tab on a group, a member profile, a project, a resource or a publication is a plugin in the groups, members, projects, resources or publications folder. Disabling one removes that tab.

The plugin groups

Thirty-seven folders ship with the platform, holding 332 plugins.

Folder	Plugins	What they do
answers	2	Extras on question pages
antispam	6	Spam detectors used when content is posted
authentication	13	Log-in methods, local and third-party
authfactors	2	Second factors for two-factor authentication
blog	2	Blog entry extras
captcha	3	Challenge widgets for forms
cart	3	Store checkout steps
citation	4	Citation formats and importers
content	13	Filters applied to content as it is rendered
courses	14	Course tabs and asset handlers
cron	14	Scheduled jobs offered to the cron manager
editors	8	WYSIWYG and plain editors
editors-xtd	4	Buttons added below an editor
extension	1	Installer support for legacy extension packages
filesystem	5	Storage back ends for project files
geocode	15	Address and coordinate lookup services
groups	18	Tabs and features on group pages
handlers	8	Viewers for published content: video, audio, PDF, LaTeX, notebooks
hubzero	5	Shared services: comments, autocompleter, system templates and tickets
members	20	Tabs and features on member profiles
metadata	1	Metadata attached to content records
newsletter	3	Newsletter composition and sending
oaipmh	2	Records exposed over OAI-PMH
projects	11	Tabs and features on projects
publications	17	Publication tabs and curation steps
resources	22	Resource tabs and features
search	26	Indexers, one per searchable content type
support	13	Ticket handling and support extras
system	29	Code that runs on every request
tags	14	Behaviour attached to tags
tools	1	Tool session viewers
update	2	Housekeeping run after an update
usage	7	Usage statistics collectors
user	11	Reactions to account creation, change and deletion
whatsnew	6	Content types listed on the What's New page
wiki	4	Wiki macros and parsers
xmessage	3	Delivery channels for internal messages

For the parameters each plugin exposes, see the generated plugin reference.

The list

Column	Meaning
Checkbox	Selects rows for the toolbar. A plugin whose files are missing has no checkbox.
Plug-in Name	The plugin's translated name, usually Group - Name, for example Authentication - Facebook. Click it to edit.
Status	Enabled or Disabled. Click the icon to toggle.
Ordering	The order plugins in the same folder run in.
Type	The plugin's folder — its group.
Element	The plugin's directory and file name.
Access	The access level required.
ID	The row's primary key.

A plugin whose files are gone is shown with a marked row and forced to disabled.

Three filters sit above the list, plus a search box. The search matches the stored name and the element, not the label in the Plug-in Name column; see the tip below.

• - Select Status -: Enabled, Disabled.
• - Select Type -: any folder that has plugins installed.
• - Select Access -: any defined access level.

Toolbar

Button	Effect
Edit	Opens the selected plugin.
Enable / Disable	Changes the state of the selected plugins.
Check In	Releases plugins left checked out by an interrupted edit.
Options	Permissions for com_plugins. There are no other settings.
Help	Opens the built-in help screen.

There is no New and no Delete. Plugins arrive and leave with the code.

Editing a plugin

The edit screen has three editable fields:

Field	Notes
Status	Enabled or Disabled.
Access	The access level required for the plugin to run for a given visitor.
Ordering	Where the plugin sits among the others in its folder.

Beside them, read-only, are the plugin's name, ID, Type (its folder) and Element, and its description from the XML manifest. Below, the plugin's own parameters appear in collapsible panels. Many plugins have none.

The toolbar is Save, Save & Close, Close and Help.

Enabling or disabling a plugin

1. Go to Extensions → Plug-in Manager.
2. Narrow the list with the - Select Type - filter or the search box.
3. Tick the plugin, then select Enable or Disable. Clicking the icon in the Status column does the same thing for a single plugin.

Disabling a plugin stops it running everywhere, front end and back end alike. If the plugin supplies a tab, that tab disappears.

The change takes effect on the next request, for everyone, and it is reversible by enabling the plugin again — which makes this one of the safer screens in the book. Two groups are the exception:

• authentication. Disabling the wrong one of these locks people out of the hub, and disabling Authentication - HUBzero locks everybody out, including you. See Authentication before you touch the group.
• system. These run on every request, and several of them are what make ordinary things work rather than adding a feature. Disable one only when you know what it does.

Changing the order plugins run in

Order matters inside a folder. Content plugins transform the same text one after another; authentication plugins are offered a log-in attempt in turn.

1. Go to Extensions → Plug-in Manager.
2. Filter by - Select Type - so you are looking at one group.
3. Select the Ordering column heading to sort by it. The up and down arrows and the order boxes only work while the list is sorted this way.
4. Move rows with the arrows, or type numbers into the boxes and select the save icon in the column heading.