About data mapping
Data mapping is
the process of transforming (or mapping) data from one application-specific
format to another. Mapping is central to the process of transferring information
between different applications and for providing collaborations
(business processes) that are independent of specific applications.
By mapping data between application-specific
business objects and generic
business objects, WebSphere creates the environment that allows
for the use of "best of breed" applications. The
WebSphere Business Integration Server Express system provides a
modular and extensible architecture for easy maintenance of your
maps.
The WebSphere map development system provides comprehensive support
for mapping
between business objects, including the following capabilities:
- Transforming data values from one or more attributes in a source
business object to one or more attributes in a destination business
object
- Establishing and maintaining relationships between data entities
that are equivalent but are represented differently and cannot be
directly transformed
- Enabling access to external mapping resources, such as third-party
mapping products and databases for performing queries
When data mapping is set up among differing applications, an
event occurrence in one application is performed in any other application
to which it is mapped. An event occurrence can be when data is created,
retrieved, updated, or deleted.
Mapping uses maps that
define the transfer (or transformation) of data between the source
and destination business
objects. In the map development environment, data is mapped from
an application-specific business object to a generic business object
or from a generic business object to an application-specific business
object. Table 1 lists the
types of mapping required.
Table 1. Mapping requirements
Direction of business
object |
Source business object |
Destination business object |
Type of map |
Connector to collaboration |
Application-specific |
Generic |
Inbound
map |
Collaboration to connector |
Generic |
Application-specific |
Outbound
map |
Example: Figure 1 illustrates how mapping occurs at run time, using
a fictionalized Employee Management collaboration as an example.
Figure 1. Data mapping at run time
The Employee Management collaboration (Collaboration1) receives an Employee business object from the source connector (App A), then sends an Employee business object to the destination connector (App B). Figure 1 illustrates
the following sequence occurs (the numbers here correspond to the
numbers in the figure):
- An event occurs in App A. The App A connector produces an App A Employee business object and sends it to the App A connector controller.
- The App A connector controller sends the App A Employee business object to the Employee Management collaboration
(Collaboration1), which resides on InterChange Server Express,
for mapping. The request includes the name of the data map that
the server must use, based on the map name specified in the connector
configuration.
- The inbound map returns
the generic Employee business object to the App A connector controller.
- The App A connector controller checks the collaborations that have
subscriptions to the generic Employee business object. In this case, Collaboration1 has a subscription, so the connector controller hands the
business object to Collaboration1.
- The collaboration performs some processing, then produces another
generic Employee business object as output, which it sends to the App B connector controller.
- The App B connector controller sends the generic business object to InterChange Server Express,
requesting mapping to the App B Employee business object.
- The outbound map returns
the application-specific Employee business object to the App B connector controller.
- The App B connector controller passes the App B Employee object to the App B connector, which can then pass the data in the business object
into App B.
The figure shows two types of maps in use:
- One inbound map from the App A Employee business object to the generic Employee business object used by the collaboration
- One outbound map from the generic Employee business object to the App B Employee business object
The Employee data moves in only one direction--from Application
A toward Application B. If you want to exchange the Employee data
in both directions between both applications, two more maps are
required:
- An inbound map from the application-specific business object
of Application B to the generic business object
- An outbound map from the generic business object to the application-specific business
object of Application A
