Ad hoc software interfacing: enterprise application integration (EAI) when middleware is overkill

Enterprise application integration (EAI) is cooperation of disparate systems and components to implement business rules in a distributed environment. "Systems and components" can be computer-aided design (CAD) or software engineering (CASE) tools, enterprise databases, COTS applications, or in-house software. Ad hoc software interfacing (AHSI) is a special kind of EAI. A tradeoff analysis classifies an EAI problem as an AHSI problem when middleware solutions are seen as heavy-handed, i.e., the planned EAI is not expected to become broad enough to justify the generality of a middleware solution or the client is unwilling to pay for a unified data model. AHSI seeks to "wire" extant software applications as components in new, larger software applications. We call applications-as-components "appliponents". AHSI seeks to minimize appliponent modification to the greatest extent possible. We demonstrate solutions to AHSI problems using XML toolkits, domain-specific language toolkits, and Microsoft BizTalk Server.