How Metadata Is Used At Build Time And Run Time; Using Enterprise Metadata Discovery To Build Services - IBM WebSphere Adapters User Manual

the appropriate programming model. It is responsible for mapping the specific
invocation to the invocation of the connector component through the JCA common
client interface (CCI).
The component developer who has knowledge of the connector invocation
interfaces and the runtime programming model, delivers the application
component. The application component consists of data exchange, application
interface, and metadata elements.
Metadata
The metadata subcomponent describes the structure of the data exchanged with
the EIS through the data exchange interfaces. The metadata can also provide
information to the connector component about how the data can be exchanged
with the EIS. For more information on the metadata subcomponent, see "How
metadata is used at build time and run time."

How metadata is used at build time and run time

Metadata is a set of characteristics that describe the structure of a WebSphere
business integration component, such as a business object, collaboration, or
adapter. Metadata describes facets common across an entire class of objects. For
example, attributes, properties, verbs, and application-specific information constitute
the metadata for a business object. Application-specific information is the part of
metadata of a business object that enables the adapter to interact with its
application or a data source.
At build time, you use the adapter to access data on an EIS, and from that data to
generate metadata in the form of annotated XML schemas. This build time
representation of the metadata contains the annotations with application-specific
information (ASI) that the adapter needs at run time in order to associate objects or
individual properties with their equivalent in the external resource.
The application-specific information portion of metadata identifies key fields,
mappings to external types, or for any other purpose that the adapter dictates. At
run time, an appropriate runtime representation of the metadata is passed to the
adapter. The adapter generates the data as XML annotations. All other components
apart from the adapter itself ignore the XML annotations. The runtime
representation must correspond to the XML schemas that were the result of the
import during enterprise metadata discovery, however their method of creations
may be specific to the given environment.
Note: The XML Schema generated as part of Enterprise Metadata Discovery can be
thought of as the canonical form.
You may prefer to construct the data object metadata programmatically from its
own metadata representation, which would have been created from the original
XML schemas, in other cases different representations, such as Records are used.
However, it is required that any application-specific information annotations in the
schemas be preserved by such environments and then provided along with the
type definition for consumption by the adapter.

Using Enterprise Metadata Discovery to build services

In addition to using enterprise metadata discovery to discover existing services,
you can use it to build services that include integrated processes that exchange
information with a technology like email or a file system.
WebSphere Adapter development overview
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