Middleware
Software that provides shared communication, integration, data exchange, or platform services between applications and underlying systems.
Middleware reduces repeated integration code and allows heterogeneous systems to cooperate. It can improve consistency, security, and operational management across an application estate.
A message broker decouples an e-commerce application from warehouse systems by accepting order messages, persisting them, and delivering them when downstream services are available.
Middleware adds another operational dependency and can hide complexity rather than remove it. Central platforms can become bottlenecks, and proprietary implementations may increase migration costs.
Middleware can include message brokers, application servers, database access layers, API management, service buses, remote procedure frameworks, and transaction coordinators. It abstracts differences in protocols and platforms while providing reusable capabilities.
Intelligent Automation
IBM — What Is Middleware? — https://www.ibm.com/think/topics/middleware; Microsoft Azure — What is middleware? — https://azure.microsoft.com/en-us/resources/cloud-computing-dictionary/what-is-middleware