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- Submitted-by: pc@hillside.co.uk (Peter Collinson)
-
- USENIX Standards Watchdog Committee
- Stephen R. Walli <stephe@usenix.org>, Report Editor
- Report on POSIX.17 - Name Space/Directory Services
-
-
- Mark Hazzard <markh@rsvl.unisys.com> reports on the meeting
- in Chicago, Illinois:
-
- Summary
-
- The POSIX.17 group is generating a user to directory services API, for
- example an API to an X.500 Directory User Agent (DUA). We are
- referring to a network idea of a directory, not the ``file which
- contains file entries'' defined in POSIX.1. It is not limited to just
- the X.500 functionality. We are using XAPIA - X/Open's Directory
- Services specification (XDS) as a basis for work. XDS is an object
- oriented interface and requires a companion specification for object
- management (XOM).
-
- XOM is a stand-alone specification with general applicability beyond
- the API to directory services. It will be used by IEEE 1224.1 (X.400
- API) and possibly other POSIX groups, and is being standardized by
- IEEE 1224.
-
- We made significant progress on a third draft of the document in
- Chicago, with the language independent specification work still to be
- done. We hope to mock ballot the document sometime after the July
- working group meeting. POSIX.12 (Protocol Independent Interfaces) and
- POSIX.17 worked together this week and arrived at a number of
- scenarios for coordinating the work. POSIX.17 is taking steps to
- determine if their work overlaps with the proposed work of certain
- ISO/SC21 (OSI) working groups.
-
- Status
-
- Commitment within the group remains adequate, but there's more than
- enough work to go around.
-
- Chris Harding, our Technical Editor (from X/Open), brought a second
- draft of the specification to the meeting. We made significant
- progress towards producing a third draft with emphasis on format
- cleanup, model, overview sections and test assertions.
-
- The ``homework'' assignments on Language Independent Specification
- (LIS) weren't completed and additional work on LIS was put on hold
- until the outcome of the SEC meeting. There seemed to be some
- confusion as to the applicability of the LIS requirement for POSIX.17
- and other Distributed Services APIs. The SEC reaffirmed the LIS
- requirement. The LIS work was reassigned to the Technical Editor.
-
- The big debate on generalizing the Object Management API never
- materialized. (Refer to the three snitch reports on the New Orleans
- 1991 meeting.) I strongly suspect this was largely due to the absence
- of Scott ``Owls in the bushes'' Guthrey at the Chicago meeting.
-
- Requirements from POSIX.12
-
- The group met with POSIX.12 (Protocol Independent Interfaces) to get
- their requirements for the POSIX.17 API. They expressed the desire
- (necessity?) to:
-
- - access existing directory services (e.g. DNS) via the
- POSIX.17 API
-
- - map the existing BSD API (e.g. gethostbyname,
- getservbyname, etc.) onto the POSIX.17 API.
-
- We discussed at length how these and other requirements should best be
- met, and produced three different scenarios describing relationships
- between the user application, the directory API(s), the directory
- service(s) and the transport service (accessed via POSIX.12's
- Simplified Network Interface).
-
- In the first scenario, the transport provider (SNI) would talk
- directly to all directory services e.g. DNS, X.500, etc. Each
- directory service resolver would be accessed through its native
- interface, of which POSIX.17 would be just another API.
-
- In scenario two, POSIX.17 would be the only API and would be used to
- access all directory services. To access a non- X.500 DUA, the
- underlying implementation might have to translate POSIX.17 calls into
- the appropriate format and invoke the corresponding resolver.
-
- In the final scenario, POSIX.17 would again be the only API, but only
- one resolver (X.500 DUA) would be used to query a single composite
- information base (DIB) containing information on all objects (e.g.
- DNS Resource Records and X.500 Distinguished Names).
-
- In each of the scenarios, impact to the POSIX.17 API will be minimal.
- However, significant impact is anticipated for the underlying
- implementation and directory information base.
-
- We discussed the relative merits of each and decided that at some
- future time a single API, resolver (agent), directory service and
- information base just might be the best for POSIX systems. We also
- recognized that POSIX systems will need to interoperate with non-POSIX
- systems for the foreseeable future, and that fact won't be lost on
- implementors.
-
- Live long and prosper! or Extending the life of our standard
-
- The base document defines both the API and the collection of objects
- managed through the API, called a ``package.''
-
- We believe that packages will be much more dynamic than the API
- itself, and could be unbundled from the API to give the API greater
- stability. We actioned the Distributed Services Steering Committee
- (DSSC) to recommend a common solution, as this problem is shared by
- other networking groups. We expect the DSSC to take this issue up in
- Santa Clara.
-
- Mock Ballot
-
- We decided to try to mock ballot our document sometime after the July
- meeting. After reaching agreement on the minimum document content for
- mock ballot, we assigned actions to get this work done. We wish to
- solicit input on requirements and feedback on our LIS and Test
- Assertion work.
-
- Is SC21 doing APIs too?
-
- With the granting of any IEEE project request (PAR) comes a
- responsibility to coordinate with other de jure standards bodies, the
- list of which is included on the PAR itself. In fulfilling this
- obligation, the group has learned (and dutifully reported to the SEC)
- that ISO SC21 is considering working on APIs to OSI application level
- services. This work has a potential to overlap the SC22 supported work
- being done by IEEE TCOS/POSIX (e.g. POSIX.17, P1224, P1238).
-
- In Closing ...
-
- The group made good solid progress in Chicago, and our document is
- beginning to ``flesh out.'' We think we understand what's required for
- test assertions and language independence, and have done several
- things to make the base document more readable. If we can maintain
- ``critical mass'' within the group, we have a good chance of going to
- mock ballot yet this year. There's a lot of work to do, so if anyone
- out there can make it to Santa Clara in July ...
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- Volume-Number: Volume 24, Number 17
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