INTERIX: UNIX Application Portability to Windows NT via an Alternative Environment Subsystem Stephen R. Walli Softway Systems, Inc. 185 Berry Street, Suite 5514, San Francisco, CA 94107
[email protected] 0. Introduction today. It does this in a price competitive manner with respect to the hardware platforms on which This paper was originally written for and it runs. The problem becomes protecting the presented at the USENIX Windows NT huge investment in applications development over Workshop, Seattle, Washington, August 1997. the past decade or more in UNIX applications. The original paper was presented under the How does one leverage and protect the existing OPENNT name. It has been updated to reflect application base while moving to Windows NT? the current architecture and experience with INTERIX. 2. Alternatives 1. The Problem There are several ways to move existing applications to Windows NT. These range from Walli’s First Law of Applications Portability: the expense of a complete re-write of the Every useful application outlives the platform on application to some form of application port. We which it was developed and deployed. will briefly look at the pros and cons of the following: Application source code portability is one of the • cornerstones of most open systems definitions. a complete re-write of the application to the The intention is that if an application is written to Win32 environment subsystem • a particular model of source-code portability, it the UNIX emulation library approach to can port relatively easily to any platform that porting the application supports the portability model. This model is • the common library strategy for porting often based on source code portability standards applications such as the ISO/IEEE family of POSIX • the Microsoft POSIX subsystem standards [1,2] and ISO/ANSI C[3], and • the INTERIX subsystem specifications that include these standards such as the Open Group's Single UNIX Specification[4].