Information Technology Reference
In-Depth Information
Downstream
Upstream
Figure 11.1
Migration paths
.
How does one determine which of the technologies is “more powerful?”
The first step is to prepare a list of features or aspects of the two
technologies that will be used as a basis for comparison. In the case of
two relational databases, these could be stored procedures, triggers, SQL
support, error handling, etc. In any such comparison, there will be features
that are in one, but not in the other. Between the two, pay attention to
features that the source has which the target does not have, rather than
the other way around, because one must ensure that all source features
can be adequately handled in the destination. However, features that exist
in the destination and not the source should not be totally ignored because
these could provide avenues for reengineering and improvements.
Risks of Migration
If you have an existing system still serving you well, what is the risk
associated with trying to migrate it? Many of these risks have little to do
with technology. Just as in any project, there is risk that the business
objectives may not be realized after the migration. Possibly another out-
come could be that if the migration is not done properly, some function-
ality is lost.
The critical factors for success include:
Sufficient knowledge of the source system at the appropriate level
of detail; this cannot be assumed because it is “your” application,
or because it has been around for a long time
A clear awareness of the technical issues involved in the migration,
particularly any impedance mismatches in technologies (the
upstream-downstream issues)
A map of the auxiliary processes, including data migration, support,
training, communication impacted by and impacting the migration
