Implement a Metatype Provider

The mechanism, implemented in the Metatype Bundle, for mapping management operations to metatypes is based on the availability of Metatype Providers as services in the OSGi framework.

According to the OSGi Metatype Specification, metadata is exported via a org.osgi.service.metatype.MetaTypeProvider. The org.osgi.service.metatype.ObjectClassDefinition and org.osgi.service.metatype.AttributeDefinition instances of a Metatype Provider contain sufficient information to automatically build rudimentary user interfaces. They can also be used to augment dedicated interfaces with accurate validations.

To register a new metadata, accessible through the Metatype API, a bundle should register its Metatype Provider as a service in the OSGi framework under the org.osgi.service.metatype.MetaTypeProvider interface.

Metadata type and version can be indicated by the values of the "metadata.type" (MetypeProviderExtern.METADATA_TYPE) and "metadata.version" (MetypeProviderExtern.METADATA_VERSION) registration properties, respectively.

If no type and version are indicated, the Metadata Manager assumes that the corresponding Metatype Provider is designed for the Configuration Admin service (see the Config Bundle description for more information about Configuration Admin metadata). This is done for backward compatibility and for handling the metatyping, defined in the OSGi Configuration Admin Specification.

To take advantage of the Extended Metatype API's features, you have to implement the following interfaces, extending the OSGi Metatype API:

Interface to Implement	Additional Functionality
MetypeProviderExtern	Creates metadata of a specified type and version, which can also contain configuration objects. As the MetatypeProviderExtern interface extends com.prosyst.util.io.Externalizable, you can serialize the metadata of the Metatype Provider and make it available to remote applications over PMP or another communication mechanism. The MetatypeProviderExtern implementation should be registered as a service in the OSGi framework.
ObjectClassDefinitionEx	Provides: Nested ObjectClassDefinitions. ObjectClassDefinition key/value modifiers (e.g. the additionally-defined load modifier indicating if the object class should be loaded by the corresponding management application) Means to search an attribute by its ID. Means to filter input (INPUT) and output (OUTPUT) attributes besides optional and required. Define a hierarchy of object classes (SUPER). ObjectClassDefinitionEx instances should be returned by the getObjectClassDefinition method of the corresponding MetaTypeProvider.
AttributeDefinitionEx	Provides: Dictionaries as attributes. Attribute key/value modifiers. More fine-grained constraints on allowed attribute values. AttributeDefinitionEx instances should be supplied by the corresponding ObjectClassDefinition.

Interface to Implement

Additional Functionality

MetypeProviderExtern

Creates metadata of a specified type and version, which can also contain configuration objects.

As the MetatypeProviderExtern interface extends com.prosyst.util.io.Externalizable, you can serialize the metadata of the Metatype Provider and make it available to remote applications over PMP or another communication mechanism.

The MetatypeProviderExtern implementation should be registered as a service in the OSGi framework.

ObjectClassDefinitionEx

Provides:

Nested ObjectClassDefinitions.
ObjectClassDefinition key/value modifiers (e.g. the additionally-defined load modifier indicating if the object class should be loaded by the corresponding management application)
Means to search an attribute by its ID.
Means to filter input (INPUT) and output (OUTPUT) attributes besides optional and required.
Define a hierarchy of object classes (SUPER).

ObjectClassDefinitionEx instances should be returned by the getObjectClassDefinition method of the corresponding MetaTypeProvider.

AttributeDefinitionEx

Provides:

Dictionaries as attributes.
Attribute key/value modifiers.
More fine-grained constraints on allowed attribute values.

AttributeDefinitionEx instances should be supplied by the corresponding ObjectClassDefinition.

Implementation of programming code to provide metadata seems to be a time- and effort-consuming process, so we suggest using the more convenient solution for metadata definition based on XML files.