xeps/inbox/s2s-over-s5066.xml

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<xep>
<header>
  <title>Server to Server communication over STANAG 5066 ARQ</title>
  <abstract>
  This specification defines operation over XMPP over the NATO STANAG 5066 data link service for point to point links (ARQ).   This enables optimized XMPP performance over HF Radio (which STANAG 5066 was designed for) and over other data links using STANAG 5066.

  </abstract>
  <legal>
    <copyright>This XMPP Extension Protocol is copyright (c) 1999 - 2015 by the XMPP Standards Foundation (XSF).</copyright>
    <permissions>Permission is hereby granted, free of charge, to any person obtaining a copy of this specification (the &quot;Specification&quot;), to make use of the Specification without restriction, including without limitation the rights to implement the Specification in a software program, deploy the Specification in a network service, and copy, modify, merge, publish, translate, distribute, sublicense, or sell copies of the Specification, and to permit persons to whom the Specification is furnished to do so, subject to the condition that the foregoing copyright notice and this permission notice shall be included in all copies or substantial portions of the Specification. Unless separate permission is granted, modified works that are redistributed shall not contain misleading information regarding the authors, title, number, or publisher of the Specification, and shall not claim endorsement of the modified works by the authors, any organization or project to which the authors belong, or the XMPP Standards Foundation.</permissions>
    <warranty>## NOTE WELL: This Specification is provided on an &quot;AS IS&quot; BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, express or implied, including, without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. In no event shall the XMPP Standards Foundation or the authors of this Specification be liable for any claim, damages, or other liability, whether in an action of contract, tort, or otherwise, arising from, out of, or in connection with the Specification or the implementation, deployment, or other use of the Specification. ##</warranty>
    <liability>In no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or agreed to in writing, shall the XMPP Standards Foundation or any author of this Specification be liable for damages, including any direct, indirect, special, incidental, or consequential damages of any character arising out of the use or inability to use the Specification (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses), even if the XMPP Standards Foundation or such author has been advised of the possibility of such damages.</liability>
    <conformance>This XMPP Extension Protocol has been contributed in full conformance with the XSF's Intellectual Property Rights Policy (a copy of which may be found at &lt;<link url='http://xmpp.org/extensions/ipr-policy.shtml'>http://xmpp.org/extensions/ipr-policy.shtml</link>&gt; or obtained by writing to XSF, P.O. Box 1641, Denver, CO 80201 USA).</conformance>
  </legal>
  <number>xxxx</number>
  <status>ProtoXEP</status>
  <type>Standards Track</type>
  <sig>Standards</sig>
  <approver>Council</approver>
  <dependencies>

    <spec>XEP 0361</spec>
    <spec>STANAG 5066</spec>
  </dependencies>
  <supersedes/>
  <supersededby/>
  <shortname>S5066</shortname>
  <author>
    <firstname>Steve</firstname>
    <surname>Kille</surname>
    <email>steve.kille@isode.com</email>
    <jid>steve.kille@isode.com</jid>
  </author>
  <revision>
    <version>0.0.1</version>
    <date>2015-08-19</date>
    <initials>sek</initials>
    <remark><p>First draft.</p></remark>
  </revision>
</header>
<section1 topic='Introduction' anchor='intro'>
  <p>
   This specification arose from requirements to operate over HF Radio, which has exceedingly high latency (sometimes minutes) low data rates (down to 75 bits/second) and poor reliablity.   STANAG 5066 is a widely used link level protocol.   Direct use of STANAG 5066 enables elimination of all extraneous end to end handshaking, which is important to optimize performance.  It also enables use of STANAG 5066 flow control, which is important for reslience.
  
  </p>
<p> 
  The solution is based on XEP-0361 "Zero Handshake Server to Server Protocol" and requires peer configuration to be established according to XEP-0361.  The data exchanged between the XMPP servers follows exactly what is specified in XEP-0316.    The data is transferred using STANAG 5066 rather than using TCP.    
 
</p>
</section1>
<section1 topic='Requirements' anchor='reqs'>
  <p>
    This specification can be considered as a profile for server to server XMPP communication, to enable XMPP deployment over HF Radio using STANAG 5066.   This profile MUST only be used where its use has been pre-agreed and configured for both participating servers.  
  </p>
</section1>

<section1 topic='Use Cases' anchor='usecases'>
  <p>
    An example scenario where this protocol is important is where two ships connected by HF Surface Wave communication only need to exchange XMPP messages. A reliable link (Soft Link) can be established using STANAG 5066 and XMPP communicated efficiently and reliably.
 
  </p>
</section1>
<section1 topic='Business Rules' anchor='rules'>
 
  <section2 topic="General Operation"> 
  <p>
    Because of potentially very low bandwidth sending server MAY perform traffic optimisation, such as selective removal of stanzas that are not adding sufficient value, like CSNs, or strip selected elements such as xhtml-im.
  </p>
    <p>
      Applications sending data over STANAG 5066 need to be aware of increased delays and any application level timers (e.g., IQ response timers) need to be set accordingly.
    </p>
  </section2>
  <section2 topic="Stream Fragmentation">
    <p>
      XEP-0361 transfer of data between a pair of XMPP servers is a byte stream flowing in each direction over TCP.   There is no other protocol or hand shaking.   
      When carried instead over STANAG 5066, these byte streams are transmitted as a sequence of blocks transferred in order 
 Each block is an XML stanza, holding message, presence or iq.   Essentially the stream is broken into blocks (stanzas) at natural boundaries XMPP boundaries, and then reassembled on reception into the original stream.
      
      
    </p>
    <p>
      XEP-0198 Stream Management MUST not be used over STANAG 5066, as reliability of stanza transfer is handled by use of STANAG 5066.  Application-layer keepalives and timeout detection such as white-space pings and XEP-0199 MUST NOT be used.
    </p>
   
  </section2>

<section2 topic="Mapping onto STANAG 5066">
  <p>
    Each stanza is transferred using the RCOP (Reliable Connection Oriented Protocol) defined in Section F.8 of Annex F of STANAG 5066.   This reliably transfers the block of data to the destination.   If a soft link needs to be established this will be done by the STANAG 5066 service.  The XEP-0361 peer agreement is supported by a flow of stanzas in each direction being transferred by RCOP.  The peer agreement will use this flow of stanzas to provide a service equivalent to the TCP connection or connections of XEP-0361.
  </p>
  <p>
    STANAG 5066 SIS Delivery Confirmation MAY be set to NODE DELIVERY, as this gives optimum network performance.  CLIENT DELIVERY MAY be used, which increases reliability as stanza delivery to the peer XMPP server is guaranteed and the sending server will receive acknowledgements equivalent to XEP-0198 support.     In the event of delivery failure, the whole RCOP PDU (Stanza) MUST be retransmitted.
  </p>

</section2>
  <section2 topic="Addressing">
    <p>  
  The peer addressing of the STANAG 5066 end points will be configured as part of the XEP-03161 peer agreement.
    </p>
    <p>
 The STANAG 5066 SAP MAY be set to any mutually agreed value.   It is RECOMMENDED that 2 is used.  This is the standard SAP for RCOP.
    </p>
<p>
  The RCOP connection ID number will be set to a mutually agreed value.  It is RECOMMENDED that 0 is used as the preferred value.
</p>
  </section2> 
</section1>


<section1 topic='Security Considerations' anchor='security'>
  <p>
    Security Considerations of XEP-0361 apply.   STANAG 5066 will frequently be employed in conjunction with link level crypto devices, which SHOULD be done when appropriate to provide data confidentiality.       
  </p>
  
</section1>
<section1 topic='STANAG 5066 Standard' anchor='iana'>
  <p>This specification uses STANAG 5066 Edition 3 "PROFILE FOR HF RADIO DATA COMMUNICATIONS" (December 2010). </p>
  <p>STANAG 5066 is a NATO UNCLASSIFED  (Releasable to the Public) document that may circulated freely.  The author has requested permission form NATO to enable publishing of this document on the Web.</p>
</section1>
  
  <section1 topic="Acknowledgements">
    <p>
      Curtis King designed and validated the approach documented in this XEP.
    </p>
    <p>
      Kevin Smith provided useful comments on this specification.
    </p>
  </section1>
</xep>