From james.isaak@ljo.dec.com Mon Jun 2 23:29:44 1997 Received: from mail13.digital.com (mail13.digital.com [192.208.46.30]) by dkuug.dk (8.6.12/8.6.12) with ESMTP id XAA12564 for ; Mon, 2 Jun 1997 23:29:40 +0200 Received: from cst.ako.dec.com by mail13.digital.com (8.7.5/UNX 1.5/1.0/WV) id RAA00556; Mon, 2 Jun 1997 17:22:18 -0400 (EDT) Received: by cst.ako.dec.com with SMTP (Microsoft Exchange Server Internet Mail Connector Version 4.0.995.52) id <01BC6F7A.2CC78DE0@cst.ako.dec.com>; Mon, 2 Jun 1997 17:26:58 -0400 Message-ID: From: James Isaak To: "'s Rinehuls, Bill'" , "'s Oblinger, Jim'" Cc: "'a WG15'" Subject: Cover note for Real Time Profiles document going to SC22 Review Date: Mon, 2 Jun 1997 17:26:56 -0400 X-Mailer: Microsoft Exchange Server Internet Mail Connector Version 4.0.995.52 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Bill, when you get the draft document for 22.15287.01, the profile work for POSIX Real-time embedded systems (IEEE 1003.13) for distribution to SC22, could you please include the cover note below with that distribution. thanks Jim Isaak ================================== To: SC22 Members June 1997 From: Jim Isaak, WG15 Convener RE: Draft POSIX Real Time Profile, WD15287-2 WG15 has asked me to ensure that SC22 members were aware the WD15287-2 profile defines subsets of the 9945-1 Standard. In the early days of profiles (remember OSI?) the concept of a profile defining a subset was inconsistent with the "layered" approach of OSI. In fact, a key value of profiles for OSI was to put together the standards that defined elements for specific layers into a coherent "whole". The POSIX work reflects a "bottom up" approach, rather than a top-down one. Work based on existing practice with systems in the field. The initial effort sought to define as much as possible of those systems which would be useful and span between diverse platform environments. There was no attempt in this process to segment out logical "layers" or "components" as separate elements. As the real time interest in POSIX expanded, so did the concept of defining subsets for embedded applications. However, the rate of additions to the 9945-1 document (which is still high) discouraged any attempt to try to do a concurrent amendment for segmentation into a number of component pieces. The real time profile work undertook this task as an external reference, indicating which elements of 9945-1 would be required in specific target environments. This process has proven useful, with some detailed user analysis (U.S. Navy funded efforts) to validate how the components aligned with actual embedded applications. This background may be useful in being aware of the nature of the draft profile, and also the rationale of how we reached this point in spite of the tradition in SGFS of not doing subsets in profiles.