I am working on the design of an upgrade framework for upgrading our database applications. We are writing this application in object-oriented Perl.

We need to install the upgrade in phases. I realized that our upgrade process is a candidate for the Command Design Pattern.

We perform the upgrade in a series of phases and need the ability to rollback phases. We need the phases to be able to execute SQL, makefiles, Perl scripts, Ksh scripts, etc. If we restart the upgrade it should keep its state and return to the last completed phase. We also need to be able to log every action.

Being new to Design Patterns, I am looking for examples of the Command Design Pattern in Perl. I am also looking for pointers on the best way to design this upgrade framework.

Futhermore, are there any pre-existing Perl upgrade tools that are open source? We are using Quest Schema Manager to find schema differences: http://www.quest.com/schema_manager/

In reply to Command Design Pattern and Rollbacks by hackdaddy

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