If Adobe Experience Manager (AEM) is the heart of your digital experience, then
Nodes form a tree-like, hierarchical structure within the repository, much like a computer's file system, serving as the building blocks for all content. Each node is defined by a specific type, which dictates the permitted properties (name-value pairs holding the actual data) and allowed child nodes.
Here is a comprehensive overview of the node structure that powers AEM.
The Three Pillars of AEM Node Types
AEM’s robust structure stems from its underlying technologies. Because AEM leverages both the Apache Sling framework for request processing and the Java Content Repository (JCR) specification for data storage, it utilizes node types originating from three distinct categories:
- JCR Node Types: The foundational, core types defined by the JCR specification (e.g.,
nt:andmix:). - Sling Node Types: Types introduced by the Apache Sling framework, often related to resource resolution and folder structures (e.g.,
sling:). - AEM Custom Node Types: Specific types created by Adobe to manage high-level CMS concepts like pages, components, workflows, and assets (e.g.,
cq:anddam:).
To inspect the definitive, current list of all associated properties and definitions, developers can always use CRXDE to browse the AEM repository at /jcr:system/jcr:nodeTypes.
1. JCR Node Types: The Foundation
JCR node types provide the basic blueprint for storing data, enforcing rules, and creating hierarchy.
Primary Node Types (The Structure)
Every node must have one declared primary node type.
nt:base: This is the abstract base primary node type from which all others inherit. It is crucial because it ensures every node exposes two properties related to its type:jcr:primaryType(the node’s type name) andjcr:mixinTypes(a list of applied mixin types).nt:unstructured: This is a highly flexible type used for storing unstructured content. It allows for any number of child nodes or properties with arbitrary names, and it supports client-orderable child nodes.nt:hierarchyNode: This abstract node type serves as the supertype for structural elements likent:fileandnt:folder.nt:file/nt:folder: These types are used to represent standard file system concepts. Annt:filenode requires a child node, typically namedjcr:content, which often uses thent:resourcetype to hold the actual file content.nt:resource: Used to represent file content itself, notably defining the mandatory binary propertyjcr:data.
Mixin Node Types (The Features)
Mixin node types are added to specific node instances to incorporate additional characteristics, often related to repository features or metadata. A node can have zero or more mixin types.
mix:title: Adds standardized metadata properties, namelyjcr:titleandjcr:description.mix:created: Used to add creation tracking properties, such asjcr:created(the date) andjcr:createdBy(the user). These properties are often auto-created and protected by the repository.mix:lastModified: Provides modification tracking viajcr:lastModifiedandjcr:lastModifiedBy.mix:referenceable: Makes a node capable of being referenced, adding the mandatory, protected, auto-createdjcr:uuidproperty which exposes the node's identifier.
2. Sling Node Types
Apache Sling defines node types generally focused on resource and folder handling. Examples of Sling node types defined primarily in the JCR resource bundle include sling:Resource, sling:Folder, and sling:VanityPath. Notably, the cq:PageContent node type inherits from sling:Resource.
3. AEM Custom Node Types
These types, typically prefixed with cq: (for content query/core) or dam: (for digital asset management), define the functionality that AEM developers interact with every day.
Web Content Management (WCM) Structures
AEM organizes content using specific WCM node types:
| Node Type | Description | Key Properties / Subnodes |
|---|---|---|
cq:Page | Defines the overall AEM page structure. | Mandatory child node jcr:content (which holds the primary content). |
cq:PageContent | Defines the content node underneath cq:Page. This node holds WCM-specific properties. | jcr:title, cq:template (path to the template), navTitle (used in navigation), hideInNav, onTime, and offTime. |
cq:Template | Defines an AEM template. | jcr:content (default content for new pages), allowedParents, allowedChildren, and ranking. |
cq:Component | Defines an AEM component. | jcr:title, componentGroup, dialog (primary dialog node), design_dialog (design dialog node). |
cq:EditConfig | Defines the configuration for the edit bar of a component. | cq:dialogMode, cq:layout, cq:actions, and subnode cq:inplaceEditing. |
Digital Asset Management (DAM)
The DAM structure uses specialized nodes for managing assets:
dam:Asset: Defines a DAM asset. It is a hierarchy node that requires a mandatory child node namedjcr:contentof typedam:AssetContent.dam:AssetContent: Defines the content structure of an asset, containing subnodes formetadataandrenditions.
Operational and Workflow Nodes
AEM uses node types to track system state and processes:
cq:ReplicationStatus: A critical mixin that exposes replication status information, including properties likecq:lastReplicated,cq:lastReplicatedBy, andcq:lastReplicationAction(which can be 'activate' or 'deactivate').cq:Workflow: Represents an active instance of a workflow.cq:WorkflowModel: Represents the definition of a workflow.cq:Tag: Defines a single tag, which can also contain other tags, thus creating a taxonomy.cq:Taggable: An abstract base mixin used for content that can be tagged.
By mastering these fundamental building blocks—from the JCR nt:base that ensures node identity, to the cq:PageContent that holds your page's metadata, and the cq:ReplicationStatus that tracks publishing state—you gain the ability to efficiently organize and retrieve all the data in your AEM instance.
In essence, understanding AEM nodes is like knowing the alphabet before writing a novel. Each node type is a specific letter or punctuation mark, and only by using the correct ones in the right hierarchy can you construct a coherent and functioning piece of content architecture.
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