Software that connects two otherwise separate applications OR separate products that serve as the glue between two applications. Middleware, or "glue", is a layer of software between the network and the applications. This software provides services such as identification, authentication, authorization, directories, and security. In today's Internet, applications usually have to provide these services themselves, which leads to competing and incompatible standards. By promoting standardization and interoperability, middleware will make advanced network applications much easier to use. For example, in RFID, middleware may link an RFID system that has been newly installed to legacy systems such as MRP, ERP, barcode management systems etc. There are many companies claiming to offer RFID middleware but globally operating companies are likely to standardise on only one offering. Oat Systems, working with Hewlett Packard claims a lead in EPC middleware.
Middleware is distinct from import and export features that may be built into one of the applications. Middleware is sometimes called plumbing because it connects two sides of an application and passes data between them. (For example, there are a number of middleware products that link a database system to a Web server. This allows users to request data from the database using forms displayed on a Web browser, and it enables the Web server to return dynamic Web pages based on the user's requests and profile.)