What is "middleware"

n. 1 (context computing English) software that functions at an intermediate layer between applications and operating system or database management system, or between client and server 2 Networking software/hardware that is deployed in the middle of, as opposed to serviced by, a packet network to enhance or provide some network function, such as caching, filtering, or firewall functionality.

Middleware in the context of distributed applications is software that provides services beyond those provided by the operating system to enable the various components of a distributed system to communicate and manage data. Middleware supports and simplifies complex distributed applications. It includes web servers, application servers, messaging and similar tools that support application development and delivery. Middleware is especially integral to modern information technology based on XML, SOAP, Web services, and service-oriented architecture.

Middleware often enables interoperability between applications that run on different operating systems, by supplying services so the application can exchange data in a standards-based way. Middleware sits "in the middle" between application software that may be working on different operating systems. It is similar to the middle layer of a three-tier single system architecture, except that it is stretched across multiple systems or applications. Examples include EAI software, telecommunications software, transaction monitors, and messaging-and-queueing software.

The distinction between operating system and middleware functionality is, to some extent, arbitrary. While core kernel functionality can only be provided by the operating system itself, some functionality previously provided by separately sold middleware is now integrated in operating systems. A typical example is the TCP/IP stack for telecommunications, nowadays included in virtually every operating system.

Middleware is computer software that provides services to software applications beyond those available from the operating system. It can be described as "software glue".

Middleware makes it easier for software developers to implement communication and input/output, so they can focus on the specific purpose of their application.