Mappings in extension mapping documents

By using mappings in extension mapping documents, you can report on data flows that are external to IBM® InfoSphere® Information Server, or that carry information between external tools and processes and InfoSphere Information Server.

A mapping is a row in an extension mapping document. Each row is a mapping that specifies that one or more source assets and target assets. A mapping can contain only source assets or only target assets. For each mapping, you can specify the functions and business rules that are used to transform the source to the target. In addition, you can supply a description of the mapping and specify custom attributes that are assigned to the mapping, except for custom attributes of type Relationship.

Data lineage reports can display the flow of data to and from the extension mapping document. These reports can also display the flow of data to and from the mappings and the individual sources and targets that are listed in the mappings.

Before you create an extension mapping document, all the source assets, target assets, and custom attributes for each mapping must exist in the catalog. If the assets are not in the catalog, you can import them by using connectors, bridges, and other import methods. Alternatively, you can create extended data sources to represent them.

You can create extension mapping documents in the following ways:
  • Use IBM InfoSphere Information Governance Catalog
  • Create comma-separated value (CSV) files that you import into the catalog
  • Use mapping specifications from IBM InfoSphere FastTrack that exist in the catalog

You can delete extension mapping documents without deleting the source assets, target assets, and custom attributes that are specified in them. If a source or target asset that appears in an extension mapping document is deleted from the catalog, the mappings that the deleted asset participated in are not valid. You must open the extension mapping document that contains the mapping and reconcile the sources and targets before you can save the document.

Planning extension mapping documents

For best lineage results, organize your extension mapping documents to contain mappings of related items that achieve a single high-level purpose. For example, a single extension mapping document might contain separate mappings for each column in a table. If you have five stored procedures that you want to capture for data lineage reporting, create separate extension mapping documents for each stored procedure. In addition, organize your extension mapping documents in folders.

If you supply a context for the source or target assets, the context is applied to every mapping in every extension mapping document that you import. Therefore, do not import extension mapping documents that do not need a context with extension mapping documents that do need a context. Import extension mapping documents that do not need a context separately from mapping documents that do need a context.

Sources and targets for extension mappings

You can use any of the following types of assets in your mappings:

You can use assets of any of these types as source assets, and map them to target assets of any of these types, depending on the information you want to display in the data lineage report. For example, you might map a database table to a method of an application if the parameters of the method are the equivalent of the database columns of a database table.

Custom attributes for mappings

Extension mapping documents as well as their mappings have custom attributes. You can use custom attributes for source-to-target mappings if the standard attributes such as name, type, and description are insufficient.
Note: Custom attributes of type Relationship are not allowed.