Model Mapper

Migrating a Model Mapping

As new versions of source and/or destination model formats are checked into the repository, it might be useful to migrate the mapping information from one Model Mapping to another, rather than simply automapping the models again. This utility is especially true if during the initial data migration process one of the models has been updated and some of the mappings have already been specified manually. To facilitate this requirement, the MIW has the ability to migrate an existing, fully defined, mapping format to a new mapping format. The new mapping can have a source and/or destination mapping format that is the same or different from those of the original mapping.

Starting the Migration Wizard

Make the Repository Manager window active and follows these steps.

To migrate a mapping to a new mapping format, first create the new Mapping Format and connect the new source and destination Model Formats to it.

If there are several sources, you will need to specify which source model in the new Mapping Format corresponds to which source model in the old Mapping Format. You can:

• perform the following actions in the Repository Manager. For each Source Model Format in the new mapping, if it is not a source of the old mapping, set a successor/predecessor link between the Version of the old Source Model Format and the Version of the new Source Model Format. Or
• Do nothing in the Repository Manager and make the corrspondence in the Migration Wizard as will be described below.

Then there are different ways to specify the source Mapping Format and start the mapping migration.

• Copy or drag the old Mapping Format, onto the new Mapping Format or
• Set a successor/predecessor link between the Version of the old Mapping Format and the Version of the new Mapping Format. Then right click on the new Mapping Format and select the Migrate mapping... option, or
• Right click on the new Mapping Format and select the Migrate mapping... option.

In all cases, a Migration Wizard window will be displayed.

Fig. 1. The Migration Wizard

If the source Mapping Format has not been specified, you can now set it by selecting a Mapping Format in the Repository Manager tree, then copy it (or drag it) and paste it (or drop it) in the From: area of the Wizard window.

The table contains the correspondence between the models in the old and the new Mapping Formats.

The first row (in bold) contains the path of the Destination Model Format. You cannot edit this line.

The next rows contain the path of the Source Model Formats in the new mapping (left column) and their correspondence in the old Mapping Format (right column).
Each row represents a Source Model Format in the new mapping. The Migration Wizard uses the Predecessor/Successor links to build the table. But you can also modify this correspondence table. To make a correspondence between a Source Model Format in the new mapping and a Source Model Format in the old mapping:

• Select the row corresponding to the Model format in the new mapping, and
• Click on the cell in the right column to display a drop-down list.
• In this list, select the path of the Model Format in the old mapping that corresponds to this Model Format in the new mapping.
• If the Model Format in the new mapping has no correspondence in the old mapping, select the entry "<new model>" in the list.

If there is only one source model in the old and the new mapping, there is only one Source Model Format row and you cannot edit it.

The Migration

The source and destination models of the original mapping are compared with the new source and destination models. The mapping of objects that exist in both the old and the new versions are kept in the new Model Mapping. The actions performed by the migration are logged in the Model Mapper log window.

Finally, the new generated Mapping Format is displayed on the screen in the Model Mapper.

Note that the generated Model Mapping may be invalid since some source objects may have been removed.
Also, if the type of the attributes has changed, it is wise to check the contents of the attribute maps they are involved in. Specifically check that the type of the arguments of the data transformations used in the operations are still compatible with the type of the attributes passed as parameters.