Middleware is a term applied to software that sits between the CPU and the application. Middleware was used in 1968 by a machine vendor who had
|Application||The application can use a transparent set of APIs for input/output|
|Middleware||The middleware interprets the underlying systems|
|Service Routines||Service routines handle tape and disk subsystems|
|Control Program||The control program is also known the system|
Middleware makes it easier for software developers to implement communication and input/output, so they can focus on the specific purpose of their application. It gained popularity in the 1980s as a solution to the problem of how to link newer applications to older legacy systems.
The middleware allowed IBM and other vendors to sell more powerful systems that could handle customer workloads with minimal changes. Over time as the mainframe became cheaper and more powerful, IBM moved to 64-bit primarily to handle even more memory. IBM uses a virtual machine manager which compartmentalizes applications so that 32-bit and newer 64-bit applications can run side by side.