Package com.zfabrik.components

Interface IComponentDescriptor

All Known Implementing Classes:
AbstractComponentDescriptor, FSCRDBComponent
public interface IComponentDescriptor
The Component Descriptor provides access to meta data as provided by component repositories (IComponentsRepository without requiring download of further component resources or other processing.

A Component Descriptor can be retrieved by calling IComponentsRepository.getComponent(String) or by a component lookup passing this interface as expected result type:

IComponentsLookup.INSTANCE.lookup(<component name>,IComponentDescriptor.class); Component metadata is provided as properties in the format of a Properties properties file. At least such property file should declare a component type: 

 com.zfabrik.component.type=<component type>
For example 
 com.zfabrik.component.type=com.zfabrik.java
would define a Java component.

Component property values may be provided dynamically through implementations of IComponentDescriptorProcessor. Given a component property someNameSpace.somePropertyName, it may be further qualified with a processing style, such as JEXL3, by appending the style to the property name separated by a colon (that needs to be escaped in property file format). In the example this would look as follows: 

 
 someNameSpace.somePropertyName\:JEXL3=....
See the JEXL3 component descriptor processor documentation for more details.
Author:
hb
See Also:

  • Field Details

    • COMPONENT_NAME

      static final String COMPONENT_NAME
      The name of the component. This property can be used conveniently to convey a component name, e.g. on a servlet request or elsewhere.
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    • COMPONENT_ALIAS

      static final String COMPONENT_ALIAS
      A comma-separated list of aliases for the component. These names are trimmed internally. All lookups and resource retrievals for an alias will be delegated to the declaring component. Aliases may not duplicate other component names or aliases on the repository level.
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    • COMPONENT_TYPE

      static final String COMPONENT_TYPE
      The type of a component. For example com.zfabrik.java for a Java component.
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    • COMPONENT_DESCRIPTOR_STYLE_PLAIN

      static final String COMPONENT_DESCRIPTOR_STYLE_PLAIN
      The default expression evaluation style for the component descriptor and default value of #COMPONENT_DESCRIPTOR_STYLE. If set to this value, no expression evaluation will take place.
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    • COMPONENT_CLZ

      static final String COMPONENT_CLZ
      The class name of the component implementation. Many component types support the use of this property, which is why it is declared here. It is by no means a necessary requirement of a component type to require an implementation class. Component's that do support specification of a component implementation class do, by convention, use JavaComponentUtil.html.loadImplementationClassFromJavaComponent() to load that implementation class.
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    • DEPENDENCIES

      static final String DEPENDENCIES
      Components declare dependency on other components by specifying a comma-separated list of component names. All components will be queried for implementations of IDependencyComponent and correspondingly invoked before the component resource is even created. This is slightly different to dependencies for system states (see there) in that these dependencies will not be revisited upon synchronisations. The declaring component will be dependent on all declared dependency components.
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    • REVISION_INFO

      static final String REVISION_INFO
      Additional revision information. This may be some original information as provided by the source.
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    • EXTENSION_POINTS

      static final String EXTENSION_POINTS
      A component may declare to an implementation of an extension point. This property is used to express a list of extension points implemented.
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    • ANY_COMPONENT_TYPE

      static final String ANY_COMPONENT_TYPE
      Component type for "any" component. The any component type requires specification of COMPONENT_CLZ and has behavior depending on the type of class:
      • If the class implements Resource, all Resource calls will be delegated.
      • If the class implements Runnable, it will be called upon system state attain operations.
      • Otherwise a check will be performed if the class is castable to the requested type and if so, the a singleton instance will be returned
      If no component type is specified on a component descriptor, it defaults to this type.
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  • Method Details

    • getName

      String getName()
      Gets the name of the component.

    • getType

      String getType()
      Gets the type of the component. A short-hand for getProperty(COMPONENT_TYPE).

    • getRevision

      long getRevision()
      Get the revision of the component. Minimum revision is zero. Revisions may not necessarily be strictly increasing, as components may be provided by different repositories over time.

    • getProperties

      Properties getProperties()
      Get the properties of this component. Note that these differ from the original configuration in these may be processed by some expression language evaluator.

    • getRawProperties

      Properties getRawProperties()
      Get the raw properties of this component. Note that unlike getProperties() the result of this method is data as defined in persistent component configuration-

    • getProperty

      String getProperty(String name)
      Just a short hand for getProperties().getProperty(String)