Many organizations still rely on IDMS, IMS, Adabas, Datacom, Supra, Ingres, Informix, and similar database technologies to run strategic applications because they’re stable, reliable, and fast. They may also be:  
Difficult to integrate
Proprietary in terms of languages and data access syntax
A maintenance challenge due to a lack of skilled resources for support
Expensive due to high or escalating license fees. 
Most successful, well-established organizations still rely on legacy database technology to run their businesses. These organizations were on the leading edge of technology as they implemented their database management systems 20 to 30 years ago. Some of them are likely still on the leading edge of technology with their use of one or more relational databases such as DB2, Oracle, SQL Server, Sybase, or Universal Data Base (UDB).

 Most organizations that replace legacy databases and applications do so because:

The license fees for the aging software are high and rising.
Teams of personnel skilled in the older technology are difficult to find, which has caused the older applications to stagnate.
The data must be easily available to other applications and platforms.
Web access is required. 
So, what options are available for organizations that rely on legacy technologies? Is there really a fine line between “stable, reliable, and fast” and “aging, closed, and expensive?” Or, are these two sets of adjectives mutually exclusive (see Figure 1)?

 

Maintain the Status Quo

Organizations satisfied with their current application functionality, license fees, productivity tools, integration capabilities, and application “look and feel” may find that continuing to maintain their legacy databases and applications is a good choice. There’s always the low-risk option to continue “as is.”

Most organizations have at least con sidered replacing legacy processing. Many were deterred from doing so by the arduous nature of the replacement process. It’s a huge time and cost investment and it’s possible that the resulting application and database won’t perform as well as the legacy system. So, if it’s not broken, why fix it?

Redevelop, Rewrite, Re-Engineer

Software rewrites let organizations introduce new capabilities into existing software while also updating the legacy databases and languages. Depending upon the extent of the functionality changes, these projects may be considered redevelopment projects, rewrites, or re-engineering. For this discussion, we’ll use rewrite to represent all three terms.

There are many advantages to a rewrite. Rewrite projects can be successful when the development team is knowledgeable about the:

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