In the first of a series of three articles, John Abbott looks at just what will be on offer to the users of the new generation of Unix software, due to hit the market towards the end of 1989. Today it’s official Unix V.4. In part two, he will look at the Open Software Foundation’s implementation based around IBM’s AIX kern el. The third article will try to assess the effects a split Unix standard will have on users of the system.
Whatever long-term effects the formation of the Open Software Foundation has on the Unix market, one thing at least has already been achieved. For the first time since it began marketing Unix, AT&T Co has had to become acutely aware of its responsibilities to Unix licensees, and is now falling over itself to involve those customers in the future evolution of the system. Instead of simply presenting Unix System V.4 as a fait accompli, AT&T has found it a necessity to try to convince its licensees that it can offer both better technology and a comparable deal to the Open Software Foundation alternative – including early access to the developing code, a relaxation of previously restrictive licensing, and assurances that it will not build into the system features that will favour either its own hardware, or worse still, that of its partner Sun Microsystems. Over the last few months, AT&T technical and marketing executives have hit the road, with seminars and briefings on the next generation of Unix, System V release 4.0, which will not be ready for beta testing until the third quarter of next year. Xenix Attendees of the AT&T roadshow have been presented with the message that the main objective of V.4 is to complete the merging of Unix variants into the mainstream System V effort. This began with a joint development with Microsoft Corp, resulting in the release of Unix System V/386 Release 3.2 earlier this year, the first version to merge Xenix compatibility into Unix System V. By cornering the Intel-based personal computer market early with Xenix, Microsoft had built up a wide base of binary-compatible software for Xenix which quickly became the most widely installed Unix version, despite deficiencies in the hardware that ran it. AT&T showed little interest in this market until the rapid rise in 80386-based products became evident. The merge, which according to AT&T Unix Europe’s Chris Papayianni includes all major features of Xenix needed to support the migration of applications – but not everything, will not have a major effect on the market until the primary Xenix marketers Microsoft Corp and the Santa Cruz Operation bring out their own releases under the Unix trade name early next year. System V Release 4 will add compatibility with the University of Berkeley, California-derived BSD variant of Unix, used mainly by scientific and technically oriented companies, including Sun Microsystems with its SunOS implementation. Although not complete, BSD conformance will include the most important BSD interfaces, such as BSD commands, the Berkeley fast file system derived from the FSS File System Switch and VNodes, support for Berkeley sockets, and the RPC Remote Procedure Call facility. The base standards for V.4 will remain Posix and the X/Open Common Applications Environment, which remain the major reference points with the Software Foundation’s alternative Unix. Conformance to Posix has been achieved by enhancing the System V signal handling with BSD extensions, and adding job control and multiple groups and ownership facilities. X/Open conformance meant only small adjustments to system parameters. Merging Unix, Xenix and BSD functionality has inevitably involved extensive kernel-level changes, and resulted in a larger kernel. This has been somewhat offset by a modular approach, according to Papayianni, which will allow AT&T to unbundle unwanted functionality for specific licensees. Office automation users, for instance, might have no desire to take the Remote Procedure Call mechanism. This approach is being reflected in more flexible licensing terms, including the relaxation of the previous
requirement in the Unix V.3 licence to take and implement the RFS Remote File Sharing facility along with Streams, whether or not it was wanted. V.4 builds on the networking framework set up in V.3 by including a much wider use of the Streams network protocol facility, which was previously limited to little more than RFS protocols. AT&T now admits that Sun’s Network File System has become the de-facto distributed file system standard, and offers both systems through the file switch mechanism across a variety of transport provides. TCP/IP has been ported on top of the Transport Layer Interface, leaving AT&T the option of migrating to the Open Systems Interconnection seven layer model at a later date. The BSD sockets facility described by Papayianni as a compatibility issue – provides a high-level interface to TCP/IP. Shrink-wrapped The other main areas stressed in AT&T’s roadshow sessions have been support for real time programming, and internationalisation. Real-time support in Unix V.4 will include user controlled process scheduling, high resolution timing services, and non blocking asynchronous input-output. Internationalisation, vital if AT&T is to push Unix into European, Middle Eastern and Far Eastern markets, will be supported by the removal of the use of the eighth bit in utilities and library routines, character set support for non-ASCII and multiple code sets, support of the ANSI C X3J11 national conventions for collating, numeric representations, date and time and so forth, and new message handling facilities. Another important issue – that of security – is also being worked on, although it is seems more likely that the B2 security rating currently being worked on will be released not in 4.0, but in a later release, probably 4.1. Working on the MS-DOS model set in the personal computer market, and on the success of Xenix in the Intel-based hardware arena, AT&T is banking on its single version of Unix as the basis for its ambitious plan to provide a binary-compatible software base for each of the major hardware platforms on which Unix runs. Applications Binary Interface standards, basically subsets of the System V Interface Definition, are currently developed or under development for Intel, Motorola, Sparc and other processors, and if AT&T has its way, will offer the possibility of shrink-wrapped compatible software for Unix – something in which, as yet, the rival Open Software Foundation appears to have shown little interest.
