Chapter 24 Portable Cocoa Although Cocoa is typically thought of as a proprietary Apple API, this is only partly true. The core is an implementation of the OpenStep specification. This core is enough to build some very rich applications, and is portable to a number of different systems. 24.1 NeXT and Sun OpenStep was created in 1993 as a result of a collaboration between Sun and NeXT. The two companies each released an implementation of the specification for their own operating systems. For a while there were two competing OpenStep operating systems for Sun's SPARC workstations, Solaris with Sun's OpenStep layer, and NeXT's OPENSTEP/Mach for SPARC. The Sun implementation used the X Display PostScript (XDPS ) extension,