Defining Nodetypes: CND

A compact node type definition (CND) defines the structure of nodes of certain types. 

The complete specification of the compact node type definition of JCR (Jackrabbit) can be found at  http://jackrabbit.apache.org/node-type-notation.html.

The CND can be viewed from the console application by using the 'export CND' function in the top menu. The node type definition defines which items (child nodes and properties) a node may or must contain and of what type they must be. It also defines if multiple values of the item are allowed. A node type always inherits from other node types and all node types inherit from the base node type nt:base.

A node type name consists of a namespace and a local name. Just like with XML, the namespace is identified by a URL that must be unique. The namespace prefix is coupled to the namespace URL by a namespace declaration at the top of a CND document. Multiple namespaces can be used. All namespaces used must be declared.

Below you see a simple example of a CND.

<'gettingstarted'='http://www.onehippo.org/gettingstarted/nt/1.0'>
<'hippo'='http://www.onehippo.org/jcr/hippo/nt/2.0'>
<'hippostd'='http://www.onehippo.org/jcr/hippostd/nt/2.0'>
<'hippostdpubwf'='http://www.onehippo.org/jcr/hippostdpubwf/nt/1.0'>

[gettingstarted:basedocument] > hippo:document, hippostd:publishableSummary,
                                hippostdpubwf:document orderable

[gettingstarted:textdocument] > gettingstarted:basedocument, hippostd:relaxed

[gettingstarted:newsdocument] > gettingstarted:basedocument, hippostd:relaxed

1. Lines 1-4 declare the namespace prefixes.
2. The note type gettingstarted:basedocument is being defined (written between [ ]).
3. it inherits from  hippo:document,  hippostd:publishableSummary and  hippostdpubwf:document and (listed after >)
4. child nodes will be orderable
5. The type gettingstarted:textdocument inherits the publication workflow capabilities from the basedocument definition and inherits from  hippostd:relaxed which contains the most common residual item definitions

Multiple node types can be defined in a single CND file. Child nodes may be of a type defined in the same namespace. Note that in a CND file the definition of a node type has to be placed above any usage of the node type in other node types.

CND's can contain more rules. It is for example possible to define:

• a property or child node to be mandatory.
• a property may be multi-valued, while a child node may allow same-name siblings. Note that different meanings are both indicated by the same keyword: multiple.
• A residual property or child node definition, which applies to a property or child node of any name. This is indicated by a * instead of the name. Note that if a residual child node definition is supplied, multiple child nodes of any name are allowed even without the keyword 'multiple', as long as the names are different.