rfc1085.txt

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        Event:     user-initiated Abort PDU received

   The provider issues the P-U-ABORT.INDICATION primitive and enters the
   IDLE state.


        Event:     any other PDU received

   If the PDU is not an Abort PDU, the provider constructs a provider-
   initiated Abort PDU, which is put on the input queue for the
   serializer.  Regardless, The provider issues the P-P-ABORT.INDICATION
   primitive and enters the the IDLE state.


                                    DATA state

        Event:     P-DATA.REQUEST primitive issued

   The user data parameter is placed in a UserData PDU, which is put on
   the input queue for the serializer.  The provider remains in the DATA
   state.


        Event:     P-RELEASE.REQUEST primitive issued

   The user data parameter is placed in a ReleaseRequest PDU, which is
   put on the input queue for the serializer.

   For the udp-based service, the provider sets the retransmission
   counter to a small value (e.g., 2), and now starts a small timer.

   Regardless, the provider enters the WAIT3 state.


        Event:     P-U-ABORT.REQUEST primitive issued

   The user data parameter is placed in an Abort PDU, which is put on
   the input queue for the serializer.  The provider enters the IDLE
   state.





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        Event:     UserData PDU received

   The provider issues the P-DATA.INDICATION primitive and remains in
   the DATA state.


        Event:     ReleaseRequest PDU received

   The provider issues the P-RELEASE.INDICATION primitive, and enters
   the WAIT4 state.


        Event:     user-initiated Abort PDU received

   The provider issues the P-U-ABORT.INDICATION primitive and enters
    the IDLE state.


        Event:     any other PDU received

   If the PDU is not an Abort PDU, the provider constructs a provider-
   initiated Abort PDU, which is put on the input queue for the
   serializer.  Regardless, the provider issues the P-P-ABORT.INDICATION
   primitive and enters the the IDLE state.


                                    WAIT3 state

        Event:     P-U-ABORT.REQUEST primitive issued

   The user data parameter is placed in an Abort PDU, which is put on
   the input queue for the serializer.  The provider enters the IDLE
   state.


        Event:     ReleaseResponse PDU received

   For the udp-based service, the timer is cancelled.  The provider
   issues the P-RELEASE.CONFIRMATION primitive and enters the IDLE
   state.


        Event:     user-initiated Abort PDU received

   The provider issues the P-U-ABORT.INDICATION primitive and enters the
   IDLE state.





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        Event:     any other PDU received

   If the PDU is not an Abort PDU, the provider constructs a provider-
   initiated Abort PDU, which is put on the input queue for the
   serializer.  Regardless, the provider issues the P-P-ABORT.INDICATION
   primitive and enters the the IDLE state.


        Event:     timer expires

   The provider decrements the retransmission counter.  If the resulting
   value is less than or equal to zero, the provider constructs a
   provider-initiated Abort PDU, which is put on the input queue for the
   serializer.  It then issues the P-P-ABORT.INDICATION primitive and
   enters the IDLE state.  Otherwise, a ReleaseRequest PDU is put on the
   input queue for the serializer, the small timer is started again, and
   the provider remains in the WAIT3 state.


                                    WAIT4 state

        Event:     P-RELEASE.RESPONSE primitive issued

   The user data parameter is placed in a ReleaseResponse PDU, which is
   put on the input queue for the serializer.  The provider now enters
   the IDLE state.

        Event:     P-U-ABORT.REQUEST primitive issued

   The user data parameter is placed in an Abort PDU, which is put on
   the input queue for the serializer.  The provider now enters the IDLE
   state.


        Event:     user-initiated Abort PDU received

   The provider issues the P-U-ABORT.INDICATION primitive and enters the
   IDLE state.


        Event:     any other PDU received

   If the PDU is not an Abort PDU, the provider constructs a provider-
   initiated Abort PDU, which is put on the input queue for the
   serializer.  Regardless, the provider issues the P-P-ABORT.INDICATION
   primitive and enters the the IDLE state.





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11. Directory Services

   Although not properly part of the presentation service, this memo
   assumes and specifies a minimal Directory service capability for use
   by the application-entity.

   The function of the Directory Service Element is to provide two
   mappings: first, a service name is mapped into an application entity
   title, which is a global handle on the service; and, second, the
   application-entity title is mapped onto a presentation address.

   The structure of presentation addresses were defined in Section 5.

   The structure of application-entity titles is less solidly agreed
   upon at the present time.  Since objects of this type are not
   interpreted by the presentation service, this memo does not specify
   their structure.  If the DIS version of association control is being
   used, then use of an OBJECT IDENTIFIER will suffice.  If the IS
   version is being employed, then application-entity titles consist of
   two parts: an application-process title and an application-entity
   qualifier.  It is suggested that the AP-Title use an OBJECT
   IDENTIFIER and that the AE-Qualifier use NULL.

   This memo requires the following mapping rules:

      1.  The service name for an OSI application-entity using the
      mechanisms proposed by this memo is:

              <designator> "-" <qualifier>

      where <designator> is a string denoting either domain name or a
      32-bit IP address, and <qualifier> is a string denoting the type
      of application-entity desired, e.g.,

              "gonzo.twg.com-mgmtinfobase"

      2.  Any locally defined mapping rules may be used to map the
      service designation into an application-entity title.

      3.  The application-entity title is then mapped into a
      presentation address, with uninterpreted transport, session, and
      presentation selectors, and one or more network addresses, each
      containing:

         -the 32-bit IP address resolved from the <designator> portion
          of the service name,

         - a set indicating which transport services are available



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           at the IP address,

         - the 16-bit port number resolved from the <qualifier>
           portion of the service name (using the Assigned Numbers
           document), and

         - optionally, a presentation selector, which is an
           uninterpreted sequence of octets.

   The method by which the mappings are obtained are straight-forward.
   The directory services element employs the Domain Name System along
   with a local table which may be used to resolve the address employing
   local rules.

   In the simplest of implementations, the DNS is used to map the
   <designator> to an IP address, and to fill-in the set of transport
   services available at the IP address.  The port number is found in a
   local table derived from the current Assigned Numbers document.
   Finally, the presentation selector is empty.

   A more ambitious implementation would use a local table to perhaps
   provide a presentation selector.  This would be useful, e.g., in
   "proxy" connections.  The network address would resolve to the proxy
   agent for the non-IP device, and the presentation selector would
   indicate to the proxy agent the particular non-IP device desired.
   This implies, of course, that the local table and the proxy agent
   bilaterally agree as to the interpretation of each presentation
   selector.

12. Remarks

   To begin, if one really wanted to implement ISO applications in a
   TCP/IP-based network, then the method proposed by [RFC1006] is the
   preferred method for achieving this.  However, in a constrained
   environment, where it is necessary to host an application layer
   entity with a minimal amount of underlying OSI infrastructure, this
   memo proposes an alternative mechanism.  It should be noted that an
   OSI application realized using this approach can be moved directly to
   an [RFC1006]-based environment with no modifications.

   A key motivation therefore is to minimize the size of the alternate
   underling infrastructure specified by this memo.  As more and more
   presentation services functionality is added, the method proposed
   herein would begin to approximate the ISO presentation protocol.
   Since this in contrary to the key motivation, featurism must be
   avoided at all costs.





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13. Acknowledgements

   Several individuals contributed to the technical quality of this
   memo:

           Karl Auerbach, Epilogue Technologies
           Joseph Bannister, Unisys
           Amatzia Ben-Artzi, Sytek
           Stephen Dunford, Unisys
           Lee Labarre, MITRE
           Keith McCloghrie, The Wollongong Group
           Jim Robertson, Bridge Communications
           Glenn Trewitt, Stanford University

14. References

     [ISO7498]  Information Processing Systems - Open Systems
                Interconnection, "Basic Reference Model", October, 1984.

     [ISO8509]  Information Processing Systems - Open Systems
                Interconnection, " Service Conventions".

     [ISO8650]  Information Processing Systems - Open Systems
                Interconnection, " Protocol Specification for the
                Association Control Service Element (Final Text
                of DIS 8650)", January, 1988.

     [ISO8822]  Information Processing Systems - Open Systems
                Interconnection, " Connection Oriented Presentation
                Service Definition (Final Text of DIS 8822)",
                April, 1988.

     [ISO8823]  Information Processing Systems - Open Systems
                Interconnection, " Connection Oriented Presentation
                Protocol Specification (Final Text of DIS 8822)",
                April, 1988.

     [ISO8824]  Information Processing Systems - Open Systems
                Interconnection, " Specification of Abstract Syntax
                Notation One (ASN.1)", December, 1987.

     [ISO8825]  Information Processing Systems - Open Systems
                Interconnection, "Specification of basic encoding rules
                for Abstract Syntax Notation One (ASN.1)",
                December, 1987.

     [ISO9072/2]  Information Processing Systems - Text Communication
                  MOTIS, " Remote Operations Part 2: Protocol



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                  Specification (Working Document for DIS 9072/2)",
                  November, 1987.

     [RFC768]  Postel, J., "User Datagram Protocol", RFC 768, USC/ISI,
               28 August 1980.

     [RFC791]  Postel, J., "Internet Protocol - DARPA Internet Program
               Protocol Specification", RFC 791, USC/ISI,
               September 1981.

     [RFC793]  Postel, J., "Transmission Control Protocol - DARPA
               Internet Program Protocol Specification", RFC 793,
               USC/ISI, September 1981.

     [RFC1006]  Rose, M., and D. Cass, "ISO Transport 1 on Top of the
                TCP Version: 3", Northrop Research and Technology
                Center, May 1987.

Appendix A:

Abstract Syntax Definitions

   RFC1085-PS DEFINITIONS ::=

   BEGIN

   PDUs ::=
           CHOICE {
               connectRequest
                   ConnectRequest-PDU,