CURRENT_MEETING_REPORT_ Reported by Peter Furniss/Consultant Minutes of the Minimal OSI Upper-Layers Working Group (THINOSI) This was our first meeting as a Working Group. Most of the time was spent reviewing the first draft of the bytestream cookbook and especially the technical choices of what OSI upper-layers features should be included. Some guiding principles emerged: o Interworking with ``full'' OSI implementations was a key purpose of the thinosi approach and must be maintained, even at the cost of some complexity. o Inclusion or exclusion of features is determined by (and determines) the set of application protocols that can be supported. o It will be little trouble to add additional features (thus widening the application range) once the basic format and style is worked out - these could be alternatives in the same document or in separate ones. o If at all possible the set of supported application protocols should include the DAP and X.400 P7 protocol. (These are not actually byte-stream in the sense we have now, but at least DAP should be possible with only a two octet change. P7 to be investigated. PRF) A number of conclusions were reached (most of these are confirmations of what is in the first draft). o Expect to receive any of the various allowed encodings of lengths, etc. o Describe sending of one application abstract-syntax and transfer syntax name (in addition to the ACSE as & ts), but also describe how, as responder, to locate and reply when these are one of a number of offered abstract syntaxes and/or transfer syntaxes (how to send and use multiple as and ts is one of the extension possibilities). o Do not use the invocations ids or the responding AP-title, AE-qualifier (ignore happily on receipt). 1 o Do not use the userdata field on ACSE A-ASSOCIATE or A-RELEASE exchanges. o Do allow the user data on the ACSE user abort to be used by the application (typically to carry application- or implementation-specific error/explanation messages). o Use Session version 2 (with the Common Upper-Layer Requirements limits on userdata). o Include the correct procedure to follow when a release collision occurs (this is different for the association initiator and responder). o Identify more clearly where the cookbook is taking advantage of a CULR part 1 restriction. o Do not include re-use of transport (although this can improve efficiency, it is always *additional* to starting with new T-connections, and thus makes the implementation more complex.) o Do not shorten the explanatory text at the beginning or move it to another document (clarify it by all means). o Change the layout of the octet sequences to a more rigid tag-length-value column format, with the datatype of primitive values in a fourth column. Indent to show the nesting if feasible. e.g., 30 80 {4 . list of transfer syntaxes 06 02 5101 oid . BER transfer syntax 00 00 }4 . e-o-c for ts list The Group was uncertain on whether the lengths of constructed elements should all be indefinite, all definite, or follow a pattern of whatever is convenient. For interworking all possibilities must be understood on receipt, but various performance payoffs are possible. The views of the mailing list will be sought. There was also some discussion of related work in other circles. o A profile for ``minimal OSI functionality'' is being developed in the OIW and EWOS regional workshops (these are the OSI profiling bodies for North America and Europe). This is intended to be part three of Common Upper-Layer Requirements. The mOSI profile and thinosi work have a common origin. At present, the upper-layer facilities supported in mOSI and in thinosi are not quite the same. It will be highly desirable for there to be one single selection of features for both. Attempts will be made to align these - in 2 particular the new draft of the cookbook should be made available to the EWOS technical liaison group (TLG) in time for their next meeting in April. o Within X/Open, a new appendix for the XTI interface is being developed that defines the use of this interface for minimal OSI. The Group will meet in Amsterdam. Attendees John Boatright bryan_boatright@ksc.nasa.gov Kevin Carosso kvc@innosoft.com George Chang gkc@ctt.bellcore.com Peter Furniss p.furniss@ulcc.ac.uk Sylvain Langlois Sylvain.Langlois@exp.edf.fr Mark Needleman mhn@stubbs.ucop.edu Geir Pedersen Geir.Pedersen@usit.uio.no Jim Romaguera romaguera@cosine-mhs.switch.ch Keith Sklower sklower@cs.berkeley.edu Klaus Truoel truoel@gmd.de William Warner warner@ohio.gov Les Wibberley lhw24@cas.org Charles Young Charles.E.Young@att.com 3