Middleware is the connectivity software that consists of a set of enabling services that allow multiple processes running on one or more machines to interact across a network. Middleware is essential to migrating mainframe applications to client/server applications and to providing for communication across heterogeneous platforms. Middleware testing consists of planning and monitoring the software testing efforts at the various testing levels like: The unit testing should be performed by the developers. Integration testing involves testing the program units and their interfaces brought together. Integration testing should be planned at the design phase and should be accomplished with an appropriate balance of developers with design knowledge and independent testers with minimal design biases. Systems testing involves in testing of the entire system to verify that system requirements including specified functions, quality, and performance characteristics are met. System testing should be planned in the requirement gathering phase and should be accomplished by independent testers. Acceptance testing involves testing the system by actual end users to ensure that it is ready for delivery and use.