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| <div class="title">Extending the UI </div>
| | The content on this page has moved to https://documentation.open-xchange.com/latest/ui/extension-points.html |
| '''Abstract'''
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| ''Abstractly speaking extension points are an architecture for letting plugins contribute functionality to other parts of the program. They form the core of the OX App Suite plugin architecture. A less detailed hands-on introduction can be found [[ AppSuite:Extending_the_UI_(Hands-on_introduction) | here]]. Some basics about the extention point concept and advantages compared to inheritance.''
| | Note: Open-Xchange is in the process of migrating all its technical documentation to a new and improved documentation system (documentation.open-xchange.com). Please note as the migration takes place more information will be available on the new system and less on this system. Thank you for your understanding during this period of transition. |
| __TOC__
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| == Introduction ==
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| === Inheritance vs. Extension points ===
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| OX App Suite uses the extension point concept to create extension points that allow a simple and flexible way to extending functionality. When system reaches a part that can be extended it asks a central registry if extensions are registered. In that case these extensions will be executes independent of the providing component (some plugin or OX App Suite itself).
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| The illustrated example compares inheritance and extension points. The main benefit of using extension points is that the programm is still the active component and it's in controll. This leads to the following advantages:
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| * Reduced coupling
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| * Increased cohesion
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| * Modularity- Re-usability
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| * Dynamic
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| [[File:Ui_ext_01.gif|frame|border|left]]
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| === Some characteristics ===
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| * good fences: extension points unregister corrupt extenders
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| * lazy loading: extenders are loaded if they are used
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| * fair play: all extenders have equal rights
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| * diversity: extension points support different extension
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| === Components ===
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| The extension point system lives in the 'io.ox/core/extensions' module and consists of these elements:
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| * extension point system: accessing the outer parts
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| * registry: manages extension points, extensions and their state
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| * extension point: part of the systems that can be extended, referenced by a unique id
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| * extension: adding/replacing functionality during runtime, referenced by a unique id
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| * baton: object used to store context, passed back through callbacks
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| == Extension Point System ==
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| <pre class="language-javascript"> //load extension points module
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| require(['io.ox/core/extensions'], function (ext) {
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| //insert code here
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| });</pre>
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| == Registry ==
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| * manages extension points, extensions and their state
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| === list points ===
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| <pre class="language-javascript"> // returns array of point ids
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| var keys = ext.keys();</pre>
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| === get/create point ===
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| <pre class="language-javascript"> //also registers a point if not happened yet
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| var mypoint = ext.point('io.ox/calendar/detail');</pre>
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| == Extension Point ==
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| * part of the systems that can be extended
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| * referenced by a unique id
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| * defines some kind of contract it's extension that to comply
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| === attributes ===
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| * id
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| * description (optional)
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| '''''example'''''
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| <pre class="language-javascript"> //get a point and it's description
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| var point = ext.point('io.ox/mail/links/toolbar'),
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| descr = point.description = '';
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| </pre>
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| === add extension ===
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| * important: existing extensions with same id will not be overwritten - use replace insted
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| * example: add extension with id 'date'
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| '''''example'''''
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| <pre class="language-javascript"> // chainable (returns mypoint)
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| point.extend({
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| id: 'example1', // Every extension is supposed to have an id
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| index: 100, // Extensions are ordered based on their indexes
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| draw: function () {
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| //draw something
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| }
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| });</pre>
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| === replace extension ===
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| * important: only extension properties will be replaced (jQuery extend is used internally)
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| * hint: ''replace'' can also be executed before extension is initially created with ''extend''
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| '''''example'''''
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| <pre class="language-javascript"> // chainable (returns mypoint)
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| mypoint.replace({
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| id: 'example1',
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| index: 100,
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| draw: function (baton) {
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| //draw something completely different
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| }
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| });</pre>
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| === use extensions===
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| * ''invoking'' extension point extensions by defining functionname, context and baton
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| * node used as context (function is called via apply(node, args))
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| * baton forwarded within programmatic flow and used for storing and exchanging data between extensions
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| <pre class="language-javascript"> mypoint.invoke(name, context, baton);</pre>
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| '''''example'''''
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| <pre class="language-javascript"> //call 'draw' of all registered extensions (order defined by index attribute)
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| //node used as context ('draw' function is called via apply(node, args))
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| //baton's data property contains relevant information about current entity (for example a mail object)
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| mypoint.invoke('draw', node, baton);</pre>
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| === access extensions ===
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| <pre class="language-javascript"> //returns array containing all extension ids
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| mypoint.keys();</pre>
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| <pre class="language-javascript"> //returns array containing all extensions
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| mypoint.all();</pre>
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| <pre class="language-javascript"> //executes callback for a specific extension
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| //chainable (returns point)
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| mypoint.get(id, callback);</pre>
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| <pre class="language-javascript"> //disabled extension will return true also;
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| var exists = mypoint.has(id);</pre>
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| '''''enabled only'''''
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| <pre class="language-javascript"> //returns array containing all enabled extensions
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| mypoint.list()</pre>
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| <pre class="language-javascript"> //returns number containing enabled extensions
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| mypoint.count()
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| </pre>
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| === enabling/disabling ===
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| <pre class="language-javascript"> var enabled = mypoint.isEnabled();</pre>
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| <pre class="language-javascript"> //chainable (returns mypoint)
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| mypoint.enable(id);</pre>
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| <pre class="language-javascript"> //chainable (returns mypoint)
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| mypoint.disable(id);</pre>
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| '''example'''
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| <pre class="language-javascript"> //disable
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| ext.point('io.ox/mail/detail/header').disable('receiveddate');</pre>
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| === underscore equivalents ===
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| * only considers enabled extensions
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| * functions returns underscore-chain object of enabled extensions
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| * take a look at http://underscorejs.org/ for more details
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| <pre class="language-javascript"> mypoint.chain()
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| mypoint.each(callback)
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| mypoint.map(callback)
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| mypoint.select(callback) //filter alias
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| mypoint.inject(callback, memo) //reduce alias
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| mypoint.pluck(propertyName)</pre>
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| '''example'''
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| <pre class="language-javascript"> // Shuffle extension order
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| ext.point('io.ox/calendar/detail').each(function (e) {
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| e.index = Math.random() * 1000 >> 0;
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| }).sort();</pre>
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| === Event Hub ===
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| * Event Hub based on jQuery's on, off, one, and trigger
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| * differences documentated for each function
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| <pre class="language-javascript"> // attach listener
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| mypoint.on(type, data, function)</pre>
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| <pre class="language-javascript"> // detach listener
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| mypoint.off(type, function)</pre>
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| <pre class="language-javascript"> // attach listener for a single execution
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| mypoint.one(type, data, function)</pre>
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| <pre class="language-javascript"> // trigger event
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| // difference: allows multiple types separated by spaces.
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| // difference: actually calls triggerHandler since we are not in the DOM.
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| mypoint.trigger(types)</pre>
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| <pre class="language-javascript"> // explicit destroy to clean up.
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| mypoint.destroy()</pre>
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| == Extension ==
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| * adding/replacing functionality during runtime
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| * referenced by a unique id
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| === Attributes ===
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| * id
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| * index (optional): numeric value used for specify order of execution (valid values also 'first', 'last')
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| * functions: as required by the extension point contract
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| ''''example'''
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| <pre class="language-javascript">
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| //defining a extension for some extension point that requires a draw function
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| {
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| id: 'example1',
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| index: 100,
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| draw: function () {
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| //draw something
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| }
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| };</pre>
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| === extensions patterns ===
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| '''io.ox/backbone/forms.js'''
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| *CheckBoxField
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| *ControlGroup
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| *DateControlGroup
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| *DatePicker
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| *ErrorAlert
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| *Header
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| *InputField
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| *Section
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| *SectionLegend
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| *SelectBoxField
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| *SelectControlGroup
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| '''io.ox/backbone/views.js'''
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| *AttributeView
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| '''io.ox/calendar/edit/recurrence-view '''
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| * RecurrenceView
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| '''io.ox/core/extPatterns/links'''
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| *Button
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| *DropdownLinks
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| *InlineLinks
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| *link
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| *ToolbarLinks
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| '''io.ox/core/tk/attachments'''
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| *AttachmentList
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| *EditableAttachmentList
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| '''io.ox/contacts/widgets/pictureUpload.js'''
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| '''io.ox/preview/main.js'''
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| *Engine
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| == Baton ==
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| Part of extension points system is a structure called baton which serves as an context object. The baton ipassed back through callbacks within programmatic flow so data exchange between extension points is simple.
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| === attributes ===
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| * data: usually contains current entity object, also used for data exchange
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| * options:
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| * flow:
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| ** disabled: stores disabled extensions (managed via baton.disable(pointId, extensionId))<br />
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| * $: used to reference a jquery node object
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| === disable extensions ===
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| <pre class="language-javascript"> //disable
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| baton.disable(pointid, extensionid);
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| //is disabled
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| var isDisabled = baton.isDisabled(pointid, extensionid);</pre>
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| '''example'''
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| <pre class="language-javascript"> var pointid = 'io.ox/mail/detail',
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| extensionid = 'example3',
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| node = $('div'),
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| baton = ext.Baton();
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| //disable extension
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| //returns undefined
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| baton.disable(pointid,extensionid);
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| //invoke extension with baton instance
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| ext.point(pointid).invoke('draw', node, baton)</pre>
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| === data exchange ===
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| '''example'''
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| <pre class="language-javascript"> //extension using baton to store data
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| {
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| id: 'example1',
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| index: 100,
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| draw: function (baton) {
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| //get the currenty process mail object
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| var mail = baton.data;
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| //append subject to current node referenced as this
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| this.append(
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| $('div').text(mail.subject);
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| )
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| //extend mail object to store some flag
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| mail.drawn = mail.drawn || {};
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| mail.drawn.subject = true;
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| //disable extension3
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| baton.disabel()
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| }
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| };
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| {
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| id: 'example2',
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| index: 200,
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| draw: function (baton) {
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| //get the currenty process mail object
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| var mail = baton.data;
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| //use value set by 'example1'
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| if(mail && mail.drawn && mail.drawn.subject) {
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| //do something
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| }
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| }
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| };
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| {
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| id: 'example3',
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| index: 300,
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| draw: function (baton) {
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| //wil not be executed if baton from 'disable example' is used
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| }
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| };</pre>
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| === ensure ===
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| * ensure that submitted object is instanceof baton
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| * return obj if it's an instanceof baton
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| * return new baton instance '''where baton.data''' is extended by obj ''or'' obj.date (if exists)
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| <pre class="language-javascript"> var baton = ext.Baton.ensure(obj)
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| </pre>
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| '''example'''
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| <pre class="language-javascript"> //new baton.data extended by object
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| var baton = ext.Baton.ensure({ id: 2 })</pre>
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| [[File:Ui_ext_02.png|Ui_ext_02.png]]
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| == Conclusion ==
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| As you can see, unlike adding functionality, customizing and modifying existing extensions is always more of a grey box operation and might incur some risks when updating the software. For example when replacing a certain functionality parts of the original functionality will have to be reimplemented, and all that extra code will have to be maintained in the future.
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| In essence extension points are better suited to integrating new functionality into the product rather than customizing existing functionality, but, when in a pinch or really wanting to change a certain part of the software, this is certainly a way to consider. At its most extreme use you could even disable all extensions for the mail detail view to register a set of your own extensions to completely change the way mails are displayed, at the cost of having to maintain your own detail view.
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| This wraps up our little tour of the OX App Suite extension point system. It is used to integrate new functionality into the OX App Suite and provides a system for 3rd party applications to become extensible themselves. It can be used to customize the existing UI at the cost of havint to know a bit more about the internals of our application. For now until more comprehensive documentation becomes available, look at the existing OX App Suite code to see concrete extensions and extension points in action.
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| <!--
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| ==== wrapp ====
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| * wrap a baton 'around' submitted object
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| * return if it's an instanceof baton
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| * return new baton instance '''''where baton''''' is extended by obj '''or''' obj.date (if exists)
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| '''example'''
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| <pre class="language-javascript"> //new baton object extended by obj
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| ext.Baton.wrap({ id: 2 })</pre>
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| [[File:Ui_ext_03.png|Ui_ext_03.png]]
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| -->
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| [[Category:AppSuite]]
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| [[Category:UI]]
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