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:
    IComponentsRepository, IComponentsLookup

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static java.lang.String ANY_COMPONENT_TYPE
      Component type for "any" component.
      static java.lang.String COMPONENT_CLZ
      The class name of the component implementation.
      static java.lang.String COMPONENT_DESCRIPTOR_STYLE_PLAIN
      The default expression evaluation style for the component descriptor and default value of #COMPONENT_DESCRIPTOR_STYLE.
      static java.lang.String COMPONENT_NAME
      The name of the component.
      static java.lang.String COMPONENT_TYPE
      The type of a component.
      static java.lang.String DEPENDENCIES
      Components declare dependency on other components by specifying a comma-separated list of component names.
      static java.lang.String EXTENSION_POINTS
      A component may declare to an implementation of an extension point.
      static java.lang.String LINK_COMPONENT_TYPE
      Component type for component (symbolic) links.
      static java.lang.String LINK_TARGET_COMPONENT
      Component descriptor property defining the link target
      static java.lang.String REVISION_INFO
      Additional revision information.

    • Method Summary

      All Methods Instance Methods Abstract Methods 
      Modifier and Type Method Description
      java.lang.String getName()
      Gets the name of the component.
      java.util.Properties getProperties()
      Get the properties of this component.
      java.lang.String getProperty​(java.lang.String name)
      Just a short hand for getProperties().getProperty(String)
      java.util.Properties getRawProperties()
      Get the raw properties of this component.
      long getRevision()
      Get the revision of the component.
      java.lang.String getType()
      Gets the type of the component.

    • Field Detail

      • COMPONENT_NAME

        static final java.lang.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.
        See Also:
        Constant Field Values

      • COMPONENT_TYPE

        static final java.lang.String COMPONENT_TYPE
        The type of a component. For example com.zfabrik.java for a Java component.
        See Also:
        Constant Field Values

      • COMPONENT_DESCRIPTOR_STYLE_PLAIN

        static final java.lang.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.
        See Also:
        Constant Field Values

      • COMPONENT_CLZ

        static final java.lang.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.
        See Also:
        Constant Field Values

      • DEPENDENCIES

        static final java.lang.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.
        See Also:
        Constant Field Values

      • REVISION_INFO

        static final java.lang.String REVISION_INFO
        Additional revision information. This may be some original information as provided by the source.
        See Also:
        Constant Field Values

      • EXTENSION_POINTS

        static final java.lang.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.
        See Also:
        Constant Field Values

      • LINK_COMPONENT_TYPE

        static final java.lang.String LINK_COMPONENT_TYPE
        Component type for component (symbolic) links. A component link delegates all lookups and resource retrievals to another, named component that is specified using the LINK_TARGET_COMPONENT property. This is a low-level built-in component type.
        See Also:
        Constant Field Values

      • LINK_TARGET_COMPONENT

        static final java.lang.String LINK_TARGET_COMPONENT
        Component descriptor property defining the link target
        See Also:
        Constant Field Values

      • ANY_COMPONENT_TYPE

        static final java.lang.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.
        See Also:
        Constant Field Values

    • Method Detail

      • getName

        java.lang.String getName()
        Gets the name of the component.

      • getType

        java.lang.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

        java.util.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

        java.util.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

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