2 Chapter 2. Architecture In this chapter, we provide an architecture overview of both the DB2 and IBM DB2 SQL Skin feature for applications that are compatible with Sybase ASE (IBM DB2 SSacSA). As its name suggests, the IBM DB2 SSacSA feature is like a skin or compatibility layer around DB2 that makes it look and feel like a Sybase ASE database to an application. The IBM DB2 SSacSA feature does this by providing most of the externals and behaviors that the applications written for Sybase ASE expect. As a result, applications migrated from Sybase ASE to DB2 with the IBM DB2 SSacSA feature are often completely unaware that the underlying database has changed, which means few to no application code changes are required. It is important to distinguish the IBM DB2 SSacSA feature from one time migration technologies, such as the IBM Migration Toolkit (MTK). With the MTK, Sybase ASE database objects and application business logic are migrated one time up front. The MTK automates straightforward conversions, but anything more complex generally requires extensive manual intervention. After the migration to DB2 is complete, the application runs natively against DB2 and the MTK is no longer required. By contrast, the IBM DB2 SSacSA feature is an enablement technology that immediately enables most Sybase ASE applications to run against DB2, usually with little to no up front conversion work required. This approach avoids the costs and risks of a traditional migration. However, it also means that the IBM DB2 SSacSA layer must remain part of the database software stack as long as © Copyright IBM Corp. 2011. All rights reserved. 15