A key issue for all of these products is their ability to generate both database-stored procedures and independent rules. Database-stored procedures are often preferable to independent rules for reasons of performance. This is a gap in USoft's functionality. These technologies are less easily adapted to the new realities of the Internet. Inference engines implement atomic rules and RETE processing algorithms.
Inference engines are also capable of modeling complex problems involving thousands of rules.
There are several ways to implement inference engines, each of which suits different purposes. For example, Neuron Data's Intelligent Rules Element is a central repository of rules, while ILOG generates decentralized rules engines. Neuron and ILOG also have different programming interfaces, even though both support Java. This is a key difference between so-called expert systems products of the 1980s and contemporary rules products. For example, Vision Software's VisionBuilder employs Microsoft's Visual Basic for the user interface portions of applications.