Classic or legacy integration involves laying down a middleware platform that helps in establishing robust and secure communication between on-prem heterogeneous apps and systems. Such platforms help in setting up mediation that involvesmessage routing, transport protocol conversion and message transformation (and enrichment). The key here is to have the integration platform mapped on top of the existing network infrastructure. The value add of having a dedicated platform is that it provides an opportunity to come up with a unified enterprise-wide integration strategy and not having a mishmash of point-to-point connectivity solutions scattered across the application landscape, the latter is a nightmare in the making going forward. EAI and ESB (refined and architected specifically for laying the groundwork for the eventual SOA) are two of the most common variants of the middleware technologies.