Developer Tool Guide > Logical View of Data > Logical Data Object Mappings
  

Logical Data Object Mappings

A logical data object mapping is a mapping that links a logical data object to one or more physical data objects. It can include transformation logic.
A logical data object mapping can be of the following types:
You can associate each logical data object with one logical data object read mapping or one logical data object write mapping.

Logical Data Object Read Mappings

A logical data object read mapping contains one or more physical data objects as input and one logical data object as output. The mapping can contain transformation logic to transform the data.
It provides a way to access data without accessing the underlying data source. It also provides a way to have a single view of data coming from more than one source.
For example, American Bank has a logical data object model for customer accounts. The logical data object model contains a Customers logical data object.
American Bank wants to view customer data from two relational databases in the Customers logical data object. You can use a logical data object read mapping to perform this task and view the output in the Data Viewer view.

Logical Data Object Write Mappings

A logical data object write mapping contains a logical data object as input. It provides a way to write to targets from a logical data object.
The mapping can contain transformation logic to transform the data. The mapping runs without accessing the underlying data target. It provides a single view of the transformed data without writing to the target.

Creating a Logical Data Object Mapping

You can create a logical data object mapping to link data from a physical data object to a logical data object and transform the data.
    1. In the Object Explorer view, double-click the logical data object that you want to add the mapping to.
    The logical data object editor opens.
    2. On the Overview tab in the General area, click Add to add a read mapping or a write mapping.
    The following image shows the Add button:
    3. Enter a name for the mapping, and then click Finish.
    The editor displays the logical data object as the mapping input or output, based on whether the mapping is a read or write mapping.
    4. Link data from a physical data object to the logical data object.
    1. a. Click the Read Mapping or Write Mapping tab to edit the mapping.
      2. The mapping editor palette opens.
    2. b. In the Object Explorer view, browse to the physical data object you want to link, and drag the physical data object into the mapping editor palette.
      3. The Add to Mapping dialog box opens.
    3. c. Choose to create a read mapping, write mapping, or lookup mapping.
    4. d. If you chose to create a read mapping, designate the object access of the read mapping as a related data object or as an independent data object.
    5. e. Click OK.
    The following image shows the result after a user drags the customer flat file data object to the mapping editor palette and designates it a read mapping.
    5. Optionally, add a reusable object to the mapping.
    You can add a logical data object or other Model repository object.
    1. a. Right-click in the mapping editor and select Add Reusable Object.
    2. b. Select one of the objects from the Model repository, and click OK.
    3. c. Choose to designate the reusable object a Read mapping, Write mapping, or Lookup mapping.
    4. d. If you chose to designate the reusable object a Read mapping, designate the object access of the Read mapping as a related data object or as an independent data object.
    5. e. Click OK.
    6. Optionally, add additional objects and transformations to the mapping, and create links between mapping objects, then click the Data Viewer view and run the mapping.
    Results appear in the Output section.