An attempt to address this with an object oriented programming model was made in the mid-1980s with Sun's NeWS windowing system, but the combination of a complex application programming interface (API) and generally poor performance led to little real-world use and the system was eventually abandoned.

Taligent was considered to be a competitor in the operating system and object markets, and Microsoft's Cairo was at least a consideration, even without any product releases from either.

Bud Tribble, a founding designer of the Macintosh and of NeXTStep, was now SunSoft's Vice President of Object Products to lead this decision.

[3] Early versions of NeXTSTEP use an "NX" prefix and contain only the Application Kit, relying on standard Unix libc types for low-level data structures.

Sun originally adopted the OpenStep environment with the intent of complementing Sun's CORBA-compliant object system, Solaris NEO (formerly known as Project DOE), by providing an object-oriented user interface toolkit to complement the object-oriented CORBA plumbing.

[2] The port involved integrating the OpenStep AppKit with the Display PostScript layer of the Sun X11 server, making the AppKit tolerant of multi-threaded code (as Project DOE was inherently heavily multi-threaded), implementing a Solaris daemon to simulate the behavior of Mach ports, extending the SunPro C++ compiler to support Objective-C using NeXT's ObjC runtime, writing an X11 window manager to implement the NeXTSTEP look and feel as much as possible, and integrating the NeXT development tools, such as Project Builder and Interface Builder, with the SunPro compiler.

Sun shipped a beta release of the OpenStep environment for Solaris on July 22, 1996,[4] and made it freely available for download in August 1996 for non-commercial use, and for sale in September 1996.

The idea was to use OpenStep code as a basis for network-wide applications running across different platforms, as opposed to using CORBA or some other system.

PDO was essentially an even more "stripped down" version of OpenStep containing only the Foundation Kit technologies, combined with new libraries to provide remote invocation with very little code.

For instance one could develop a high-powered financial modeling application using D'OLE, and then call it directly from within Microsoft Excel.

OPENSTEP for Mach supported Intel x86-based PC's, Sun's SPARC workstations, and NeXT's own 68k-based architectures, while the HP PA-RISC version was dropped.

[5][4] NeXT also delivered an implementation running on top of Windows NT 4.0 called OPENSTEP Enterprise (often abbreviated OSE).

This allowed their existing customer base to continue using their tools and applications, but running them on Windows, to which many of them were in the process of switching.

After acquiring NeXT, Apple intended to ship Rhapsody as a reworked version of OPENSTEP for Mach for both the Mac and standard PCs.

[citation needed] GNUstep, a free software implementation of the NeXT libraries, began at the time of NeXTSTEP, predating OPENSTEP.

GNUstep also features a fully functional development environment, reimplementations of some of the newer innovations from macOS's Cocoa framework, as well as its own extensions to the API.