Guidelines for Autonomic Service Agents
draft-carpenter-anima-asa-guidelines-00
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| Authors | Brian E. Carpenter , Sheng Jiang | ||
| Last updated | 2016-09-30 | ||
| Replaced by | draft-ietf-anima-asa-guidelines, RFC 9222 | ||
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draft-carpenter-anima-asa-guidelines-00
Network Working Group B. Carpenter
Internet-Draft Univ. of Auckland
Intended status: Informational S. Jiang
Expires: April 3, 2017 Huawei Technologies Co., Ltd
September 30, 2016
Guidelines for Autonomic Service Agents
draft-carpenter-anima-asa-guidelines-00
Abstract
This document proposes guidelines for the design of Autonomic Service
Agents for autonomic networks. It is based on the Autonomic Network
Infrastructure outlined in the ANIMA reference model, making use of
the Autonomic Control Plane and the Generic Autonomic Signaling
Protocol.
Status of This Memo
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This Internet-Draft will expire on April 3, 2017.
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
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include Simplified BSD License text as described in Section 4.e of
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Logical Structure of an Autonomic Service Agent . . . . . . . 3
3. Interaction with the Autonomic Infrastructure . . . . . . . . 4
3.1. Interaction with the security mechanisms . . . . . . . . 4
3.2. Interaction with the ACP . . . . . . . . . . . . . . . . 4
3.3. Interaction with GRASP and its API . . . . . . . . . . . 5
3.4. Interaction with Intent mechanism . . . . . . . . . . . . 6
4. Design of GRASP Objectives . . . . . . . . . . . . . . . . . 6
5. Life Cycle . . . . . . . . . . . . . . . . . . . . . . . . . 6
6. Coordination . . . . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 6
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
10.1. Normative References . . . . . . . . . . . . . . . . . . 6
10.2. Informative References . . . . . . . . . . . . . . . . . 7
Appendix A. Change log [RFC Editor: Please remove] . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
This document proposes guidelines for the design of Autonomic Service
Agents (ASAs) in the context of an Autonomic Network (AN) based on
the Autonomic Network Infrastructure (ANI) outlined in the ANIMA
reference model [I-D.ietf-anima-reference-model]. This
infrastructure makes use of the Autonomic Control Plane (ACP)
[I-D.ietf-anima-autonomic-control-plane] and the Generic Autonomic
Signaling Protocol (GRASP) [I-D.ietf-anima-grasp].
There is a considerable literature about autonomic agents with a
variety of proposals about how they should be characterized. Some
examples are [DeMola06], [Huebscher08], [Movahedi12] and [GANA13].
However, for the present document, the basic definitions and goals
for autonomic networking given in [RFC7575] apply . According to RFC
7575, an Autonomic Service Agent is "An agent implemented on an
autonomic node that implements an autonomic function, either in part
(in the case of a distributed function) or whole."
The reference model [I-D.ietf-anima-reference-model] expands this by
adding that an ASA is "a process that makes use of the features
provided by the ANI to achieve its own goals, usually including
interaction with other ASAs via the GRASP protocol
[I-D.ietf-anima-grasp] or otherwise. Of course it also interacts
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with the specific targets of its function, using any suitable
mechanism. Unless its function is very simple, the ASA will need to
be multi-threaded so that it can handle overlapping asynchronous
operations. It may therefore be a quite complex piece of software in
its own right, forming part of the application layer above the ANI."
A basic property of an ASA is that it is a relatively complex
software component that will in many cases control and monitor
simpler entities in the same host or elsewhere. For example, a
device controller that manages tens or hundreds of simple devices
might contain a single ASA.
The remainder of this document offers guidance on the design of ASAs.
NOTE: This is an early version of this document. It is expected to
grow considerably.
2. Logical Structure of an Autonomic Service Agent
As mentioned above, all but the simplest ASAs will be multi-threaded
programs.
A typical ASA will have a main thread that performs various initial
housekeeping actions such as:
o Obtain authorization credentials.
o Register the ASA with GRASP.
o Acquire relevant policy Intent.
o Define data structures for relevant GRASP objectives.
o Register with GRASP those objectives that it will actively manage.
o Launch a self-monitoring thread.
o Enter its main loop.
The logic of the main loop will depend on the details of the
autonomic function concerned. Whenever asynchronous operations are
required, extra threads will be launched. Examples of such threads
include:
o A background thread to repeatedly flood an objective to the AN, so
that any ASA can receive the objective's latest value.
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o A thread to accept incoming synchronization requests for an
objective managed by this ASA.
o A thread to accept incoming negotiation requests for an objective
managed by this ASA, and then to conduct the resulting negotiation
with the counterpart ASA.
o A thread to manage subsidiary non-autonomic devices directly.
These threads should all either exit after their job is done, or
enter a wait state for new work, to avoid blocking other threads
unnecessarily.
According to the degree of parallelism needed by the application,
some of these threads might be launched in multiple instances. In
particular, if negotiation sessions with other ASAs are expected to
be long or to involve wait states, the ASA designer might allow for
multiple simultaneous negotiating threads, with appropriate use of
queues and locks to maintain consistency.
The main loop itself could act as the initiator of synchronization
requests or negotiation requests, when the ASA needs data or
resources from other ASAs. In particular, the main loop should watch
for changes in policy Intent that affect its operation. It should
also do whatever is required to avoid unnecessary resource
consumption, such as including an arbitrary wait time in each cycle
of the main loop.
The self-monitoring thread is of considerable importance. Autonomic
service agents must never fail. To a large extent this depends on
careful coding and testing, with no unhandled error returns or
exceptions, but if there is nevertheless some sort of failure, the
self-monitoring thread should detect it, fix it if possible, and in
the worst case restart the entire ASA.
3. Interaction with the Autonomic Infrastructure
3.1. Interaction with the security mechanisms
TBD
3.2. Interaction with the ACP
TBD
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3.3. Interaction with GRASP and its API
GRASP [I-D.ietf-anima-grasp] is expected to run as an operating
system kernel module with its API [I-D.liu-anima-grasp-api] available
in user space. Thus ASAs may operate without special privilege,
unless they need it for other reasons. The ASA's view of GRASP is
built around GRASP objectives (Section 4), defined as data structures
containing administrative information such as the objective's unique
name, and its current value. The format and size of the value is not
restricted by the protocol, except that it must be possible to
serialise it for transmission in CBOR [RFC7049], which is no
restriction at all in practice.
The GRASP API offers the following features:
o Registration functions, so that an ASA can register itself and the
objectives that it manages.
o A discovery function, by which an ASA can discover other ASAs
supporting a given objective.
o A negotiation request function, by which an ASA can start
negotiation of an objective with a counterpart ASA. With this,
there is a corresponding listening function for an ASA that wishes
to respond to negotiation requests, and a set of functions to
support negotiating steps.
o A synchronization function, by which an ASA can request the
current value of an objective from a counterpart ASA. With this,
there is a corresponding listening function for an ASA that wishes
to respond to synchronization requests.
o A flood function, by which an ASA can cause the current value of
an objective to be flooded throughout the AN so that any ASA can
receive it.
For further details and some additional housekeeping functions, see
[I-D.liu-anima-grasp-api].
This API is intended to support the various interactions expected
between most ASAs, such as the interactions outlined in Section 2.
However, if ASAs require additional communication between themselves,
they can do so using any desired protocol. One option is to use
GRASP discovery and synchronization as a rendez-vous mechanism
between two ASAs, passing communication parameters such as a TCP port
number as the value of a GRASP objective.
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3.4. Interaction with Intent mechanism
TBD
4. Design of GRASP Objectives
TBD
5. Life Cycle
TBD, citing "A Day in the Life of an Autonomic Function"
[I-D.peloso-anima-autonomic-function].
6. Coordination
TBD, citing "Autonomic Functions Coordination"
[I-D.ciavaglia-anima-coordination].
7. Security Considerations
TBD. Authorization of ASAs is a subject for future study.
8. IANA Considerations
This document makes no request of the IANA.
9. Acknowledgements
TBD.
10. References
10.1. Normative References
[I-D.ietf-anima-autonomic-control-plane]
Behringer, M., Eckert, T., and S. Bjarnason, "An Autonomic
Control Plane", draft-ietf-anima-autonomic-control-
plane-03 (work in progress), July 2016.
[I-D.ietf-anima-grasp]
Bormann, C., Carpenter, B., and B. Liu, "A Generic
Autonomic Signaling Protocol (GRASP)", draft-ietf-anima-
grasp-07 (work in progress), September 2016.
[RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
October 2013, <http://www.rfc-editor.org/info/rfc7049>.
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10.2. Informative References
[DeMola06]
De Mola, F. and R. Quitadamo, "An Agent Model for Future
Autonomic Communications", Proceedings of the 7th WOA 2006
Workshop From Objects to Agents 51-59, September 2006.
[GANA13] ETSI GS AFI 002, , "Autonomic network engineering for the
self-managing Future Internet (AFI): GANA Architectural
Reference Model for Autonomic Networking, Cognitive
Networking and Self-Management.", April 2013,
<http://www.etsi.org/deliver/etsi_gs/
AFI/001_099/002/01.01.01_60/gs_afi002v010101p.pdf>.
[Huebscher08]
Huebscher, M. and J. McCann, "A survey of autonomic
computing--degrees, models, and applications", ACM
Computing Surveys (CSUR) Volume 40 Issue 3 DOI:
10.1145/1380584.1380585, August 2008.
[I-D.ciavaglia-anima-coordination]
Ciavaglia, L. and P. Peloso, "Autonomic Functions
Coordination", draft-ciavaglia-anima-coordination-01 (work
in progress), March 2016.
[I-D.ietf-anima-reference-model]
Behringer, M., Carpenter, B., Eckert, T., Ciavaglia, L.,
Pierre, P., Liu, B., Nobre, J., and J. Strassner, "A
Reference Model for Autonomic Networking", draft-ietf-
anima-reference-model-02 (work in progress), July 2016.
[I-D.liu-anima-grasp-api]
Carpenter, B., Liu, B., Wang, W., and X. Gong, "Generic
Autonomic Signaling Protocol Application Program Interface
(GRASP API)", draft-liu-anima-grasp-api-01 (work in
progress), June 2016.
[I-D.peloso-anima-autonomic-function]
Pierre, P. and L. Ciavaglia, "A Day in the Life of an
Autonomic Function", draft-peloso-anima-autonomic-
function-01 (work in progress), March 2016.
[Movahedi12]
Movahedi, Z., Ayari, M., Langar, R., and G. Pujolle, "A
Survey of Autonomic Network Architectures and Evaluation
Criteria", IEEE Communications Surveys & Tutorials Volume:
14 , Issue: 2 DOI: 10.1109/SURV.2011.042711.00078,
Page(s): 464 - 490, 2012.
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[RFC7575] Behringer, M., Pritikin, M., Bjarnason, S., Clemm, A.,
Carpenter, B., Jiang, S., and L. Ciavaglia, "Autonomic
Networking: Definitions and Design Goals", RFC 7575,
DOI 10.17487/RFC7575, June 2015,
<http://www.rfc-editor.org/info/rfc7575>.
Appendix A. Change log [RFC Editor: Please remove]
draft-carpenter-anima-asa-guidelines-00, 2016-09-30:
Initial version
Authors' Addresses
Brian Carpenter
Department of Computer Science
University of Auckland
PB 92019
Auckland 1142
New Zealand
Email: brian.e.carpenter@gmail.com
Sheng Jiang
Huawei Technologies Co., Ltd
Q14, Huawei Campus, No.156 Beiqing Road
Hai-Dian District, Beijing, 100095
P.R. China
Email: jiangsheng@huawei.com
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