Generic Autonomic Signaling Protocol Application Program Interface (GRASP API)
draft-liu-anima-grasp-api-01
The information below is for an old version of the document.
| Document | Type |
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| Authors | Brian E. Carpenter , Bing Liu , Wendong Wang , Xiangyang Gong | ||
| Last updated | 2016-06-23 | ||
| Replaced by | draft-ietf-anima-grasp-api, RFC 8991 | ||
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draft-liu-anima-grasp-api-01
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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