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How to Maximize ROI When Re-Facing Legacy Systems

by Chris Durand

Over the last few years we have completed a number of “legacy modernization” projects wherein we build a browser-based user-interface for iSeries (AS/400) and 3270-based applications while keeping the business logic in the host application (“re-facing”).  Here are a few things we’ve learned:

Re-facing without Extension is a Waste

The main reason a browser-based interface to an application is useful is because everyone knows how to use a web browser.  If all you are doing in your web interface is converting function keys to clickable links and adding eye-candy, you will struggle to find enough ROI to make it worthwhile.  If you are trying to eliminate costs associated with deploying green screen emulator software to user desktops, you are better off deploying a web-based emulator product instead of beginning a screen re-facing development project. Continue reading


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Options for Modernizing Legacy Systems

by Chris Durand

Say you have an existing iSeries (AS/400) or mainframe “green screen” application.  It’s been around for a long time and has a solid, reliable code base based on years (decades?) of testing and real-world use.  It generally works pretty well, and doesn’t change much.

That’s all great until you find that as the business is moving forward it is becoming increasingly difficult to update the application to support the future business direction.  Sure, you’ve found a few creative solutions to work around application limitations so far, but fundamentally you need something other than a short-term fix.

You basically have the following modernization options:

  • Rewrite it using the language/technology/platform of your choice.
    • Pros: Complete flexibility to keep what is working and rework what is not.
    • Cons: Expensive.  Risky (does anyone really know all the business rules buried in decades of code?).  Slow to implement.
  • Convert the code to a new platform using an automated tool.  I’ve not had experience with this, however, I suspect it is cheaper than rewriting, but still very risky.  Plus you probably don’t get the full benefits of a true rewrite. Continue reading