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Versions: 00 01 02 03 04 05 06 draft-ietf-anima-grasp-api

Network Working Group                                       B. Carpenter
Internet-Draft                                         Univ. of Auckland
Intended status: Standards Track                             B. Liu, Ed.
Expires: December 26, 2016                           Huawei Technologies
                                                                 W. Wang
                                                                 X. Gong
                                                         BUPT University
                                                           June 24, 2016


   Generic Autonomic Signaling Protocol Application Program Interface
                              (GRASP API)
                      draft-liu-anima-grasp-api-01

Abstract

   This document specifies the application programming interface (API)
   of the Generic Autonomic Signaling Protocol (GRASP).  The API is used
   for Autonomic Service Agents (ASA) calling the GRASP protocol module
   to communicate autonomic network signalings with other ASAs.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on December 26, 2016.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect



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   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  GRASP API for ASA . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Design Principles . . . . . . . . . . . . . . . . . . . .   3
     2.2.  API definition  . . . . . . . . . . . . . . . . . . . . .   4
       2.2.1.  Parameters and data structures  . . . . . . . . . . .   4
       2.2.2.  Registration  . . . . . . . . . . . . . . . . . . . .   6
       2.2.3.  Discovery . . . . . . . . . . . . . . . . . . . . . .   8
       2.2.4.  Negotiation . . . . . . . . . . . . . . . . . . . . .   8
       2.2.5.  Synchronization and Flooding  . . . . . . . . . . . .  13
   3.  Example Logic Flows . . . . . . . . . . . . . . . . . . . . .  15
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  16
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  16
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  16
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  16
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  16
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  16
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  17

1.  Introduction

   As defined in [I-D.ietf-anima-reference-model] , the Autonomic
   Serveice Agent (ASA) is the atomic entity of an autonomic function;
   and it is instantiated on autonomic nodes.  When ASAs communicate
   with each other, they should use the Generic Autonomic Signaling
   Protocol (GRASP) [I-D.ietf-anima-grasp].

   As the following figure shows, the GRASP could contain two major sub-
   layers.  The bottom is the GRASP base protocol module, which is only
   responsible for sending and recieving GRASP messages.  The upper
   layer is some extended functions based upon GRASP basic protocol.
   For example, [I-D.liu-anima-grasp-distribution] is one of the
   extended functions.

   It is desirable that ASAs can be designed as portable user-space
   programs using a portable API.  In many operating systems, the GRASP
   module will therefore be split into two layers, one being a library
   that provides the API and the other being kernel code containing
   common components such as multicast handling and the discovery cache.
   The details of this are system-dependent.





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             +----+                              +----+
             |ASAs|                              |ASAs|
             +----+                              +----+
                |                                   |
                | GRASP Function API                |
                |                                   |
             +------------------+                   |GRASP API
             | GRASP Extended   |                   |
             | Function Modules |                   |
             +------------------+                   |
             +------------------------------------------+
             |                   GRASP Library          |
             |  GRASP Module - - - - - - - - - - - - - -|
             |                   GRASP Kernel           |
             +------------------------------------------+

   Both the GRASP base module and the extended function modules should
   be available to the ASAs.  Thus, there needs to be two sub-sets of
   API.  However, since the extended functions are expected to be added
   in an incremental manner, it is inappropriate to define the function
   APIs in a single document.  This document only defines the base GRASP
   API.

2.  GRASP API for ASA

2.1.  Design Principles

   The assumption of this document is that any Autonomic Service Agent
   (ASA) needs to call a GRASP module that handles protocol details
   (security, sending and listening for GRASP messages, waiting, caching
   discovery results, negotiation looping, sending and receiving
   sychronization data, etc.) but understands nothing about individual
   objectives.  So this is a high level abstract API for use by ASAs.
   Individual language bindings should be defined in separate documents.

   An assumption of this API is that ASAs may fall into various classes:

   o  ASAs that only use GRASP for discovery purposes.

   o  ASAs that use GRASP negotiation but only as an initiator (client).

   o  ASAs that use GRASP negotiation but only as a responder.

   o  ASAs that use GRASP negotiation as an initiator or responder.

   o  ASAs that use GRASP synchronization but only as an initiator
      (recipient).




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   o  ASAs that use GRASP synchronization but only as a responder and/or
      flooder.

   o  ASAs that use GRASP synchronization as an initiator, responder
      and/or flooder.

   The API also assumes that one ASA may support multiple objectives.
   Nothing prevents an ASA from supporting some objectives for
   synchronization and others for negotiation.

   This is a preliminary version.  Two particular gaps exist:

   o  Authorization of ASAs is out of scope.

   o  The Rapid mode of GRASP is not supported.

2.2.  API definition

2.2.1.  Parameters and data structures

   Wherever a 'timeout' parameter appears, it is an integer expressed in
   milliseconds.  If it is zero, the GRASP default timeout
   (GRASP_DEF_TIMEOUT, see [I-D.ietf-anima-grasp]) will apply.  If no
   response is received before the timeout expires, the call will fail
   unless otherwise noted.

   An 'objective' parameter is a data structure with the following
   components:

   o  name (UTF-8 string) - the objective's name

   o  neg (Boolean) - True if objective supports negotiation (default
      False)

   o  synch (Boolean) - True if objective supports synchronization
      (default False)

   o  loop_count (integer) - Limit on negotiation steps etc. (default
      GRASP_DEF_LOOPCT, see [I-D.ietf-anima-grasp])

   o  value - a specific data structure expressing the value of the
      objective.  The format is language dependent, with the constraint
      that it can be validly represented in CBOR (default integer = 0).

   An 'ASA_locator' parameter is a data structure with the following
   contents:





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   o  locator - The actual locator, either an IP address or an ASCII
      string.

   o  ifi (integer) - The interface identifier index via which this was
      discovered - probably no use to a normal ASA

   o  expire (system dependent type) - The time on the local system
      clock when this locator will expire from the cache

   o  is_ipaddress (Boolean) - True if the locator is an IP address

   o  is_fqdn (Boolean) - True if the locator is an FQDN

   o  is_uri (Boolean) - True if the locator is a URI

   o  diverted (Boolean) - True if the locator was discovered via a
      Divert option

   o  protocol (integer) - Applicable transport protocol (IPPROTO_TCP or
      IPPROTO_UDP)

   o  port (integer) - Applicable port number

   In most calls, an 'asa_nonce' parameter is required.  It is generated
   when an ASA registers with GRASP, and any call in which an invalid
   nonce is presented will fail.  It is an up to 24-bit opaque value
   (for example represented as a uint32_t, depending on the language).
   It should be unpredictable; a possible implementation is to use the
   same mechanism that GRASP uses to generate Session IDs
   [I-D.ietf-anima-grasp].  Another possible implementation is to hash
   the name of the ASA with a locally defined secret key.

   In some calls, a 'session_nonce' parameter is required.  This is an
   opaque data structure as far as the ASA is concerned, used to
   identify calls to the API as belonging to a specific GRASP session.
   In fully threaded implementations this parameter might not be needed,
   but it is included to act as a session handle if necessary.  It will
   also allow GRASP to detect and ignore malicious calls or calls from
   timed-out sessions.  A possible implementation is to form the nonce
   from the underlying GRASP Session ID and the source address of the
   session.

   Other parameters are described in the following sections.








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2.2.2.  Registration

   These functions are used to register an ASA and the objectives that
   it supports with the GRASP module.  If an authorization model is
   added to GRASP, it would be added here.

   o  register_asa()

         Input parameter:

            name of the ASA (UTF-8 string)

         Return parameters:

            success (Boolean)

            result

               if success: asa_nonce (integer)

               if not success: error message (UTF-8 string)

         This initialises state in the GRASP module for the calling
         entity (the ASA).  In the case of success, an 'asa_nonce' is
         returned which the ASA must present in all subsequent calls.
         In the case of failure, the ASA has not been authorized and
         cannot operate.

   o  deregister_asa()

         Input parameters:

            asa_nonce (integer)

            name of the ASA (UTF-8 string)

         Return parameters:

            success (Boolean)

            result

               if success: none

               if not success: error message (UTF-8 string)

         This removes all state in the GRASP module for the calling
         entity (the ASA), and deregisters any objectives it has



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         registered.  Note that these actions must also happen
         automatically if an ASA crashes.

         Note - the ASA name is strictly speaking redundant in this
         call, but is present for clarity.

   o  register_objective()

         Input parameters:

            asa_nonce (integer)

            objective (structure)

            discoverable (Boolean - default False)

         Return parameters:

            success (Boolean)

            result

               if success: none

               if not success: error message (UTF-8 string)

         This registers an objective that this ASA supports and may
         modify.  The 'objective' becomes a candidate for discovery.
         However, discovery responses should not be enabled until the
         ASA calls listen_negotiate() or listen_synchronize(), showing
         that it is able to act as a responder.  This can be overridden
         by setting the optional parameter 'discoverable' to True,
         intended for objectives that are only defined for GRASP
         discovery, and which do not support negotiation or
         synchronization.  The ASA may negotiate the objective or send
         synchronization or flood data.  Registration is not needed if
         the ASA only wants to receive synchronization or flood data for
         the objective concerned.  This call may be repeated for
         multiple objectives.

   o  deregister_objective()

         Input parameters:

            asa_nonce (integer)

            objective (structure)




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         Return parameters:

            success (Boolean)

            result

               if success: none

               if not success: error message (UTF-8 string)

         The 'objective' must have been registered by the calling ASA;
         if not, this call fails.  Otherwise, it removes all state in
         the GRASP module for the given objective.

2.2.3.  Discovery

   o  discover()

         Input parameters:

            asa_nonce (integer)

            objective (structure)

            timeout (integer)

            flush (Boolean - default False)

         Return parameters:

            locator_list (structure)

         This returns a list of discovered 'ASA_locator's for the given
         objective.  If the optional parameter 'flush' is True, any
         locally cached locators for the objective are deleted first.
         Otherwise, they are returned immediately.  If not, GRASP
         discovery is performed, and all results obtained before the
         timeout expires are returned.  If no results are obtained, an
         empty list is returned after the timeout.

         This should be called in a separate thread if asynchronous
         operation is required.

2.2.4.  Negotiation

   o  request_negotiate()

         Input parameters:



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            asa_nonce (integer)

            objective (structure)

            peer (ASA_locator)

            timeout (integer)

         Return parameters:

            success (Boolean)

            session_nonce (structure)

            result

               if success: objective (structure)

               if not success: error message (UTF-8 string)

         This function opens a negotiation session.  The 'objective'
         parameter must include the requested value, and its loop count
         should be set to a suitable value by the ASA.  If not, the
         GRASP default will apply.

         The 'peer' parameter is the target node; it must be an
         'ASA_locator' as returned by discover().  If the peer is null,
         GRASP discovery is performed first.

         If the 'success' parameter is 'true', the negotiation has
         successfully started.  There are then two cases:

         1.  The 'session_nonce' parameter is null.  In this case the
             negotiation has succeeded (the peer has accepted the
             request).  The returned objective contains the value
             accepted by the peer.

         2.  The 'session_nonce' parameter is not null.  In this case
             negotiation must continue.  The returned objective contains
             the first value proffered by the negotiation peer.  Note
             that this instance of the objective must be used in the
             subsequent negotiation call because it also contains the
             current loop count.  The 'session_nonce' must be presented
             in all subsequent negotiation steps.

             This function must be followed by calls to 'negotiate_step'
             and/or 'negotiate_wait' and/or 'end_negotiate' until the




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             negotiation ends. 'request_negotiate' may then be called
             again to start a new negotation.

         If the 'success' parameter is 'false', the negotiation has
         failed for the reason given in the result parameter.  An
         exponential backoff is recommended before any retry.

         This should be called in a separate thread if asynchronous
         operation is required.

         Special note for the ACP infrastructure ASA: It is likely that
         this ASA will need to discover and negotiate with its peers in
         each of its on-link neighbors.  It will therefore need to know
         not only the link-local IP address but also the physical
         interface and transport port for connecting to each neighbor.
         One implementation approach to this is to include these details
         in the 'session_nonce' data structure, which is opaque to
         normal ASAs.

   o  listen_negotiate()

         Input parameters:

            asa_nonce (integer)

            objective (structure)

         Return parameters:

            success (Boolean)

            result

               if success: session_nonce (structure)

               if not success: error message (UTF-8 string)

            requested_objective (structure)

         This function instructs GRASP to listen for negotiation
         requests for the given 'objective'.  It also enables discovery
         responses for the objective.  It will block waiting for an
         incoming request, so should be called in a separate thread if
         asynchronous operation is required.  Unless there is an
         unexpected failure, this call only returns after an incoming
         negotiation request.  When it does so, 'requested_objective'
         contains the first value requested by the negotiation peer.
         Note that this instance of the objective must be used in the



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         subsequent negotiation call because it also contains the
         current loop count.  The 'session_nonce' must be presented in
         all subsequent negotiation steps.

         This function must be followed by calls to 'negotiate_step'
         and/or 'negotiate_wait' and/or 'end_negotiate' until the
         negotiation ends. 'listen_negotiate' may then be called again
         to await a new negotation.

         If an ASA is capable of handling multiple negotiations
         simultaneously, it may call 'listen_negotiate' simultaneously
         from multiple threads.  The API and GRASP implementation must
         support re-entrant use of the listening state and the
         negotiation calls.  Simultaneous sessions will be distinguished
         by the threads themselves, the GRASP Session IDs, and the
         underlying unicast transport sockets.

   o  stop_listen_negotiate()

         Input parameters:

            asa_nonce (integer)

            objective (structure)

         Return parameters:

            success (Boolean)

            result

               if success: null

               if not success: error message (UTF-8 string)

         Instructs GRASP to stop listening for negotiation requests for
         the given objective, i.e., cancels 'listen_negotiate'.  Of
         course, it must be called from a different thread.

   o  negotiate_step()

         Input parameters:

            asa_nonce (integer)

            session_nonce (structure)

            objective (structure)



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            timeout (integer)

         Return parameters:

            Exactly as for 'request_negotiate'

         Executes the next negotation step with the peer.  The
         'objective' parameter contains the next value being proffered
         by the ASA in this step.

   o  negotiate_wait()

         Input parameters:

            asa_nonce (integer)

            session_nonce (structure)

            timeout (integer)

         Return parameters:

            success (Boolean)

            result

               if success: null

               if not success: error message (UTF-8 string)

         Delay negotiation session by 'timeout' milliseconds.

   o  end_negotiate()

         Input parameters:

            asa_nonce (integer)

            session_nonce (structure)

            reply (Boolean)

            reason (UTF-8 string)

         Return parameters:

            success (Boolean)




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            result

               if success: null

               if not success: error message (UTF-8 string)

         End the negotiation session.

         'reply' = True for accept (successful negotiation), False for
         decline (failed negotiation).

         'reason' = optional string describing reason for decline.

2.2.5.  Synchronization and Flooding

   o  synchronize()

         Input parameters:

            asa_nonce (integer)

            objective (structure)

            peer (ASA_locator)

            timeout (integer)

         Return parameters:

            success (Boolean)

            result

               if success: objective (structure)

               if not success: error message (UTF-8 string)

         This call requests the synchronized value of the given
         'objective'.

         If the objective was already flooded, the flooded value is
         returned immediately in the 'result' parameter.  In this case,
         the 'source' and 'timeout' are ignored.

         Otherwise, synchronization with a discovered ASA is performed.
         The 'peer' parameter is an 'ASA_locator' as returned by
         discover().  If 'peer' is null, GRASP discovery is performed
         first.



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         This call should be repeated whenever the latest value is
         needed.

         Call in a separate thread if asynchronous operation is
         required.

         Since this is essentially a read operation, any ASA can use it.
         Therefore GRASP checks that the calling ASA is registered but
         the objective doesn't need to be registered by the calling ASA.

         In the case of failure, an exponential backoff is recommended
         before retrying.

   o  listen_synchronize()

         Input parameters:

            asa_nonce (integer)

            objective (structure)

         Return parameters:

            success (Boolean)

            result

               if success: null

               if not success: error message (UTF-8 string)

         This instructs GRASP to listen for synchronization requests for
         the given objective, and to respond with the value given in the
         'objective' parameter.  It also enables discovery responses for
         the objective.

         This call is non-blocking and may be repeated whenever the
         value changes.

   o  stop_listen_synchronize()

         Input parameters:

            asa_nonce (integer)

            objective (structure)

         Return parameters:



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            success (Boolean)

            result

               if success: null

               if not success: error message (UTF-8 string)

         This call instructs GRASP to stop listening for synchronization
         requests for the given 'objective', i.e. it cancels a previous
         listen_synchronize.

   o  flood()

         Input parameters:

            asa_nonce (integer)

            objectives (type)

         Return parameters:

            success (type)

            result (type)

               if success: name (type)

               if not success: error message (UTF-8 string)

         This call instructs GRASP to flood the given synchronization
         objective(s) and their value(s) to all GRASP nodes.  The
         'objectives' parameter is a list of one or more objectives.

         Checks that the ASA registered each objective.

         This call may be repeated whenever any value changes.

3.  Example Logic Flows

   TBD

   (Until this section is written, some Python examples can be found at
   <https://www.cs.auckland.ac.nz/~brian/graspy/Briggs.py> and
   <https://www.cs.auckland.ac.nz/~brian/graspy/Gray.py>.)






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4.  Security Considerations

   Security issues for the GRASP protocol are discussed in
   [I-D.ietf-anima-grasp].  Authorization of ASAs is a subject for
   future study.

   The 'asa_nonce' parameter is used in the API as a first line of
   defence against a malware process attempting to imitate a
   legitimately registered ASA.  The 'session_nonce' parameter is used
   in the API as a first line of defence against a malware process
   attempting to hijack a GRASP session.

5.  IANA Considerations

   This does not need IANA assignment.

6.  Acknowledgements

   This document was produced using the xml2rfc tool [RFC7749].

7.  References

7.1.  Normative References

   [I-D.ietf-anima-grasp]
              Bormann, C., Carpenter, B., and B. Liu, "A Generic
              Autonomic Signaling Protocol (GRASP)", draft-ietf-anima-
              grasp-05 (work in progress), May 2016.

7.2.  Informative References

   [I-D.ietf-anima-reference-model]
              Behringer, M., Carpenter, B., Eckert, T., Ciavaglia, L.,
              Liu, B., Nobre, J., and J. Strassner, "A Reference Model
              for Autonomic Networking", draft-ietf-anima-reference-
              model-01 (work in progress), March 2016.

   [I-D.liu-anima-grasp-distribution]
              Liu, B. and S. Jiang, "Information Distribution over
              GRASP", draft-liu-anima-grasp-distribution-01 (work in
              progress), March 2016.

   [RFC7749]  Reschke, J., "The "xml2rfc" Version 2 Vocabulary",
              RFC 7749, DOI 10.17487/RFC7749, February 2016,
              <http://www.rfc-editor.org/info/rfc7749>.






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Authors' Addresses

   Brian Carpenter
   Department of Computer Science
   University of Auckland
   PB 92019
   Auckland  1142
   New Zealand

   Email: brian.e.carpenter@gmail.com


   Bing Liu (editor)
   Huawei Technologies
   Q14, Huawei Campus
   No.156 Beiqing Road
   Hai-Dian District, Beijing  100095
   P.R. China

   Email: leo.liubing@huawei.com


   Wendong Wang
   BUPT University
   Beijing University of Posts & Telecom.
   No.10 Xitucheng Road
   Hai-Dian District, Beijing 100876
   P.R. China

   Email: wdwang@bupt.edu.cn


   Xiangyang Gong
   BUPT University
   Beijing University of Posts & Telecom.
   No.10 Xitucheng Road
   Hai-Dian District, Beijing 100876
   P.R. China

   Email: xygong@bupt.edu.cn











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