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There is more than one way to extend access to applications over Internet or intranet connections.
There is more than one way to extend access to applications over Internet or intranet connections.
The simplest, fastest way to Web-enable programs is to replace existing terminals with Web clients via terminal applications such as Microsoft Windows NT Terminal Server. This is a fast and cheap process aimed at users who already employ the legacy applications through terminals.
A more sophisticated method is to use Java and J++ thin clients. Java applications can connect directly with the legacy system, improving performance. But this approach increases concerns over security and data integrity unless the new interface includes the extensive safeguards and error checking that legacy applications have built up over the years.
Another option is to support current users and expand legacy applications to new users by simplifying the user interface with pull-down menus and pop-up screens. This is a much more ambitious project than merely pasting a Web interface on legacy terminal access, but migration tools can perform a lot of the work, and there's no threat to the existing legacy safeguards. The reduced training required for new users could justify the cost.
Simplified interfaces could also allow occasional users to directly utilize applications that previously required a trained operator.
An example of an application mining tool that takes this approach is WRQ Inc.'s object-oriented Apptrieve, which treats mainframe applications as either objects or databases and insulates the legacy software so completely from the conversion that developers don't even need to be familiar with the legacy program. The back-end, or legacy, code and its underlying logic is untouched.
Finally, the most complex and expensive legacy-to-Web conversion is a complete reworking of the legacy application, typically into a modern language. Because of the time and expense it requires, this is practical only when the functionality of the legacy application is woefully inadequate.
'John McCormick
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