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Developing Core Components

When to Use the Core Components?

As the Core Components are all-new, and offer multiple benefits, it is recommended for new AEM projects to use them. For existing projects, a migration should be part of a larger project effort, for example a rebranding or overall refactoring.
Therefore, Adobe provides following recommendations:
  • New Projects
    New projects should always attempt to use Core Components. If Core Components cannot be used directly or extended to satisfy project requirements, then create a custom component following the component architecture set forth in core components. Except where not otherwise possible, avoid using the foundation components .
  • Existing Projects
    Recommendation is keep using the foundation components , unless a site or component refactoring is planned. As they are very widely used by most existing projects, the foundation components will continue to be supported.
  • New Custom Components
    Assess if an existing Core Component may be customized . If not, recommendation is to build a new custom component following the Component Guidelines .
  • Existing Custom Components
    If your components work as expected, then keep them as they are. If not, refer to "New Custom Components" above.

How to Succeed with the Core Components

The Core Components are powerful, flexible, and easy to use and customize. Following a few key guidelines will ensure that your project with the Core Components is a success.

Migrating to the Core Components

Any new project should be implemented with Core Components. However existing projects will usually have extensive implementations of the Foundation Components.
A larger effort on an existing project (for example a rebranding or overall refactoring) often offers a chance to migrate to the Core Components. To facilitate this migration, Adobe has provided a number of migration tools to encourage the adoption of the Core Components and the latest AEM technology.
The AEM Modernization Tools allow for the easy conversion of:
  • Static templates to editable templates
  • Design configurations to policies
  • Foundation Components to Core Components
  • Classic UI to Touch-Enabled UI
For further information about the usage of these tools, see their documentation .
The AEM Modernize Tools are a community effort and are not supported or warrantied by Adobe.

Core Component Support

Core Components are an integral part of AEM and supported as is, under the same terms and conditions as if they were delivered as part of the Quickstart.
Like other AEM product features, the general rule is: Components are first announced to be deprecated, and the earliest removed for the following AEM release. That gives customers at least one release cycle to move to the new version of the component, before dropping its support.
The version of each component clearly states the AEM versions that it supports. When support ceases for a version of AEM, then so does the support of the Core Components for that version of AEM.
For details about the support of component customizations, see the Customizing Core Components page.

Technical Capabilities

The following table gives an overview of the differences between core components and foundation components.
For details about their authoring capabilities and options to pre-configurable them, refer to the authoring page about them .
Core Component
Foundation Component
Logic implementation
Java POJOs with Sling Models annotations
JSP code
Markup definition
JSP code
XSS sanitization
Automated by HTL
Mostly manual
CSS classes naming
Standardized naming convention based on Block Element Modifier (BEM) notation (as of release 2.0.0)
Custom schemes
Dialog definition
Coral 2 + Classic UI
JSON output
Default Sling servlet
Unit Tests + Integration Tests
Integration Tests
Via Quickstart
Adobe proprietary
Via pull request
Not possible
Fully compliant with the # (
Only partially compliant with the WCAG 2.0 AA standard

Component List

The following table lists the available Core Components, linking to their API, and indicates which foundation components they replace.
Core Component
Replaced Foundation Component(s)
Responsive page working with template editor
/libs/foundation/components/page /libs/wcm/foundation/components/page
Page hierarchy navigation
H1-H6 title
/libs/foundation/components/title /libs/wcm/foundation/components/title
Rich text
/libs/foundation/components/text /libs/foundation/components/table /libs/wcm/foundation/components/text
Smart and lazy loading of optimal rendition size
/libs/foundation/components/image /libs/foundation/components/adaptiveimage /libs/foundation/components/logo /libs/foundation/components/mobileimage /libs/foundation/components/mobilelogo /libs/wcm/foundation/components/image
List of pages
/libs/foundation/components/list /libs/foundation/components/mobilelist /libs/wcm/foundation/components/list
Facebook and Pinterest sharing widget
Responsive form paragraph system
/libs/foundation/components/form/start /libs/foundation/components/form/end
Text input field
/libs/foundation/components/form/text /libs/foundation/components/form/password
Multiple options input field
/libs/foundation/components/form/checkbox /libs/foundation/components/form/radio /libs/foundation/components/form/dropdown
Hidden input field
Submit or custom button
A site navigation component that lists the nested page hierarchy
/libs/foundation/components/topnav /libs/foundation/components/mobiletopnav
A language and country switcher that lists the global language structure
A search component that displays the results as in-place suggestions in a drop-down menu
Allows the content author to easily create a teaser to further content using an image, title, or rich text and linking to further content or other actions
Allows the content author to organize page content within multiple tabs
Allows the content author to organize content in a rotating carousel of slides
Allows for the display of a content fragment
Allows for the display a list of content fragments
Separates content on a page
Organize content panels in a collapsible accordion
Organize components within a container
Create a button on a page
Add a downloadable asset to a page
Add an experience fragment to a page
Embed an external resource within a page
Provide a visual representation of progress towards a goal
Presents a PDF document on a page

Upcoming Components

For an overview of the upcoming Core Component road map see the project wiki on GitHub .

Upgrade of Core Components

One benefit of versioned components is that it allows to separate the migration to a new AEM version from the migration to new component versions. Also, if new component versions are available, it allows for the individual migration of each component to the new version.
Migrations to a new AEM version won't impact how the Core Components work, provided that their versions also support the new AEM version that is being migrated to. Customizations made to the Core Components should not be affected either, as long as they don't use APIs that have been deprecated or removed .
Migrations to new versions of the Core Components won't impact how the component works either, but new features might be introduced to page authors, which might require some configuration by a template editor, in case the default behavior isn't desired. Customizations however might need to be adapted, for more details see the Customizing Core Components page.