O PEN NT UNIX Application Portability to Windows …….ppt

OPENNT: UNIX Application Portability to Windows NT Stephen R. Walli Softway Systems Inc. stephe@ The Problem Walli抯 First Law of Applications Portability: Every useful application outlives the platform on which it was originally developed and deployed Application Migration Alternatives Complete re-write to Win32 UNIX emulation libraries Common portability library The Microsoft POSIX subsystem The OPENNT subsystem Windows NT Today ... Winsock TCP/IP POSIX.1 subsystem Windows NT kernel Hardware abstraction layer Windows NT command shell Windows NT commands, networking system administration Win32 applications Win95 GUI Win32 APIs Win32 subsystem Internet and Intranet 3rd party WINDOWS NT ? Caveat Emptor This presentation is not about which operating system interface (UNIX or Win32) is better or worse. It is about solving a very real application programming problem using a unique strategy based on the design of Windows NT. Application Rewrite to Win32 Simple ANSI C applications should port directly. Most 搃nteresting?applications require access to system services. The cost of a rewrite increases with the complexity of the application. Win32-based UNIX Emulation There are at least 3 packages in this space: UWIN (Bell Labs), NuTCracker (DataFocus), Portage (Concensys) A large set of applications may compile cleanly in this environment, but many may not behave as expected because they run as clients of the Win32 subsystem. Win32 Libraries (cont.) fork( )/exec( ) semantics File system semantics Use of the Win32 API Common Library Layer Common porting library is a special case of the normal application porting strategy Microsoft POSIX Subsystem Implements ISO/IEC 9945-1:1990 exactly (which includes ANSI/ISO C library) Not particularly 揳ccessible? Poorly documented Surprisingly functional OPENNT Design Goals To provide a complete porting and run-time environment for UNIX application code. To provide true semantics for the system servic