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Some thoughts on legacy modernization with business rules


I saw this white paper by IBM on Legacy Modernization with business rules and thought I should quickly re-summarize my point of view on this and link to my various posts on the topic. The white paper does a nice, if IBM-centric, job of outlining the key issues:

  • You don’t need to modernize the whole application
  • Decision making components are often the highest change, most difficult to maintain pieces of mainframe systems
  • Externalizing these components using a business rules management system dramatically reduces the maintenance costs of a legacy application while both improving its agility and positioning you for replatforming later.

The basic steps:

  • Analyze the code to find the decisions
  • Rework the code to isolate these decisions in their own component
  • Work out the rules for these decisions and document them in a business rules management system
    You can analyze the code to find rules but starting with the original policies/regulations is often much more effective as code analysis gives you VERY technical rules
  • Use the BRMS to redeploy the rules as a decision service that the legacy application can access
  • Retire the replaced code

Read the white paper, even if you are not an IBM customer, as it is a nice summary. For those of you who want my opinion, check out these posts:

You can find these posts and more using the Legacy Modernization tag


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