Middleware is a term which refers to the set of services composed of IAA, APIs, and management systems which support the needs of a distributed, networked computing environment. As the name ``middleware'' suggests, it is, using the hierarchical model, a layer of services which sits between applications and the services they access. An excellent overview of middleware can be found in RFC 27681. The RFC's authors admit that even today, middleware is still not a well-defined term but the above definition is consistent with the RFC's and is sufficient for the purposes of this paper.
Middleware, at first glance, seems somewhat innocuous or invisible, especially when it works well. Looks can be deceiving, however. Middleware is a critical component in the CoS model. It is the middleware which supports the creation and removal of users, provides the ability to verify an identity, manages the addition and removal of services associated with user ids, and even the addition and removal of services available to users. Within the enterprise, a good middleware solution makes the delivery of services transparent to users. There is no need to know which server is providing a given service and a single login/password provides access to all of the enterprise's services, subject to whatever policies have been established. In the business-to-business world, where multiple enterprises establish electronic relationships, middleware will perform the same function but it is complicated by the fact that there are currently no middleware standards in place.
The IT community today certainly recognizes the importance of middleware. The Internet2 community has formed a working group to investigate middleware. Companies like Microsoft (Active Directory) and Novell (NDS) have committed huge amounts of money and, in effect, bet their corporate futures on gaining adoption of their middleware implementations as standards. This makes middleware, in the authors' opinion, the single most important component in future networked computing environments. The Open Source community, and the Linux community in particular, must recognize its importance.
A proprietary solution such as Active Directory or NDS will irreparably harm the Open Source movement. The success of Linux in the enterprise has largely been because of its adherence to open standards and availability of source code. This has permitted managers to easily deploy Linux into existing enterprise IT architectures where open standards exist. If the middleware standard isn't open the implications are obvious. For example, consider the SMB file protocol and the open-source Samba software. With the introduction of Microsoft Windows 2000 and the incorporation of Active Directory into file and print services, Samba's viablity was immediately threatened. This scenario will repeat itself over and over unless the middleware is standards-based and open.