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Versions: 00 01                                                         
ICNRG                                                    M. Arumaithurai
Internet-Draft                                                   J. Chen
Intended status: Informational                                     X. Fu
Expires: September 6, 2015                      University of Goettingen
                                                         K. Ramakrishnan
                                     University of California, Riverside
                                                              J. Seedorf
                                                           March 5, 2015

                   Enabling Publish/Subscribe in ICN


   Information-Centric Networks (ICN) provide substantial flexibility
   for users to obtain information without regard to the source of the
   information or its current location.  Publish/subscribe (pub/sub)
   systems have gained popularity in society to provide the convenience
   of removing the temporal dependency of the user having to indicate an
   interest each time he or she wants to receive a particular piece of
   related information.  Such an "information-centric" communication
   model should be supported in the new ICN network paradigm.  This
   document outlines some research directions for ICN with respect to
   enhancing the inherently pull-based ICN approaches for achieving
   efficient pub/sub capability.

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
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   This Internet-Draft will expire on September 6, 2015.

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Copyright Notice

   Copyright (c) 2015 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
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Pub/Sub Communication . . . . . . . . . . . . . . . . . . . .   3
   3.  Scenarios of Pub/Sub Architecture . . . . . . . . . . . . . .   4
     3.1.  Online Social Networks and RSS Feeds  . . . . . . . . . .   4
     3.2.  Online Gaming and Audio/Video Conferencing  . . . . . . .   4
     3.3.  Notification Systems in Disaster  . . . . . . . . . . . .   5
   4.  Requirements of an Efficient Pub/Sub Architecture . . . . . .   5
   5.  Related Work  . . . . . . . . . . . . . . . . . . . . . . . .   7
     5.1.  IP/Overlay Multicast  . . . . . . . . . . . . . . . . . .   7
     5.2.  Named-Data Networking (NDN) . . . . . . . . . . . . . . .   8
     5.3.  CCN . . . . . . . . . . . . . . . . . . . . . . . . . . .   8
     5.4.  Content-Oriented Publish/Subscribe(COPSS) . . . . . . . .   9
     5.5.  PSIRP Project . . . . . . . . . . . . . . . . . . . . . .   9
     5.6.  NetInf Project (http://www.netinf.org)  . . . . . . . . .   9
     5.7.  Pursuit Project (http://www.fp7-pursuit.eu/)  . . . . . .   9
     5.8.  Other Related Works . . . . . . . . . . . . . . . . . . .   9
   6.  Standardisation Considerations  . . . . . . . . . . . . . . .  10
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  11
   Appendix A.  Acknowledgment . . . . . . . . . . . . . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   This document points out the need to support publish/subscribe (pub/
   sub) capabilities in ICN and the problems with the existing
   solutions.  Further, the document discusses potential directions for
   enhancing Information Centric Networking (ICN) to achieve efficient

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   Section 2 describes the pub/sub systems and the challenges of such
   systems to the current Internet.  Section 3 demonstrates the use of
   pub/sub systems in different scenarios.  Section 4 outlines the
   requirements of an efficient pub/sub architecture and Section 5
   discusses the related works and some possible shortcomings.  In
   Section 6 we brief our standardisation considerations.

2.  Pub/Sub Communication

   Users increasingly desire access to information, ranging from news,
   financial markets, healthcare, to disaster relief and beyond,
   independent of who published it, where it is located, and often, when
   it was published.  Typical representation of these usages are
   microblogs, RSS feed, social network, search engines, etc.  A
   consumer may not wish (or it may even be infeasible) to receive all
   of the "channels" belonging to a myriad of information providers that
   disseminate items of interest, either on demand (such as web,
   twitter, blogs and social networks), or tune to a broadcast channel
   (e.g., television, radio, newspaper).  In these cases, the consumer
   would rather prefer obtaining the data based on Content Descriptors
   (CD) such as a keyword, a tag, or a property of the content
   (publisher identity, published date etc.).

   Publish/subscribe (pub/sub) systems are particularly suited for such
   kind of large scale content-oriented information dissemination, and
   provide the exibility for users to subscribe to information of
   interest, without being intimately tied to when that information is
   made available by publishers.  With the use of an appropriate
   interface, users can select and filter the information desired so
   that they receive only what they are interested in, often
   irrespective of the publisher.

   Intelligent end-systems and information aggregators (e.g., Google
   News and Yahoo!  News, cable and satellite providers) have
   increasingly adapted their interfaces to provide a content-oriented
   pub/sub-based delivery method.  However, these mechanisms are built
   on top of a centralized server based framework and can also result in
   a waste of network resources as shown in
   [Ramasubramanian2006][Katsaros2011], since the Internet protocol
   suite is focused on end-to-end delivery of data.  Furthermore, issues
   of "coverage" and "timeliness" still exist in such forms of
   dissemination, where the aggregator may be selective in what
   information is made available.

   Information-Centric Networks (ICN) is a new network paradigm that
   intendeds to achieve large scale data delivery with greater ease for
   users, greater scalability in terms of the amount of information
   disseminated as well as number of producers and consumers of

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   information, and greater efficiency in terms of network and server
   resource utilization.

   It is also desirable for such a network to assist the pub/sub
   communication model that delivers the information from any of the
   producers to all subscribers.  Moreover, it is desirable for the
   network to assist in delivering fine-grained information to the

   Recently, works such as
   [Schmidt2012],[Carzaniga2011],[Chen2011],[Chen2012] have also
   highlighted the need for ICN to support a pub/sub like communication

3.  Scenarios of Pub/Sub Architecture

   In this section, we list several use cases of pub/sub architectures
   in ICN.  They help us to understand the requirements of an efficient
   pub/sub architecture and why the existing solutions fall short.

3.1.  Online Social Networks and RSS Feeds

   Online social networks (e.g., Twitter, Facebook, etc.) and Rich Site
   Summary (RSS) feeds are typical use cases for a content-centric pub/
   sub system.  In such systems, the receivers receive messages either
   from friends, followees, or from some information aggregators.  They
   do not care which exact machine is sending the message (content-
   centric), nor do they know when and what is the name of the next
   message they are going to receive (temporal separation).

   To prevent the receivers from polling all the possible providers,
   existing systems use web servers as rendezvous points: the publishers
   send new messages to the servers and the receivers/subscribers poll
   the server periodically.  This still causes great wastage for the
   (HTTP) servers answering "304 - Not Modified" repeatedly since the
   message update frequency is usually lower than the polling frequency.

3.2.  Online Gaming and Audio/Video Conferencing

   Massively multiplayer online role-playing games (MMORPGs, e.g.,
   Counter-Strike, Quake, World of Warcraft, etc.) and audio/video
   conferencing (e.g., Skype meeting, Web Whiteboard, Etherpad, etc.) is
   another kind of content-centric pub/sub systems.  Similar to the
   social network scenario, users in such systems only care about the
   content, either the area of interest (AoI) or the conference
   partners, and they do not know when and from where the next message
   will come.  But different from the previous scenario, such systems

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   require real-time update (message) delivery and these messages are
   usually smaller in size compared to the online social networks.

   Many of these systems choose to use HTTPS or direct TCP connection
   between the server and the users to enable the capability of server
   "pushing" the updates to the user.  But maintaining such links are
   costly.  MMORPGs usually limit the number of players in a same game
   which greatly reduces the interesting of these games.

3.3.  Notification Systems in Disaster

   Disasters have often disrupted communications because of damages to
   critical infrastructure.  For instance in the aftermath of the
   Japanese Earthquake in 2011, approximately 1,200,000 fixed telephone
   lines and 15,000 base-stations were not functioning.  On average, 22%
   (with peaks up to 65% in some areas) of the base-stations had to shut
   down due to the lack of power or damages to the infrastructure.

   Contradictory to the loss of available hardware capacity, during and
   in the aftermath of a disaster, there is a substantial increase in
   the amount of traffic generated because of the natural anxiety and
   panic among people and the need to organize rescue and emergency
   services.  Many of these traffic are in the form of a pub/sub
   communication model, e.g., the government needs to publish some
   notifications (recovery status, new shelter locations, etc.), the
   refugees need to notify their friends about their safety, or people
   needs to ask for help from ambulances or fire brigade.  In the
   Japanese case, the congestion caused by such traffic resulted in
   restrictions in voice traffic up to 95%, including emergency priority

4.  Requirements of an Efficient Pub/Sub Architecture

   Given a pub/sub communication model as described in Section 2, on a
   high-level one can derive the following (incomplete) list of basic

   o  Decouple publishers and subscribers: In an ideal pub/sub
      environment, publishers only focus on their core task of
      publishing while not having to maintain membership status, and
      subscribers receive content from a multitude of sources without
      having to worry about maintaining a list of publishers and
      frequently polling them for the availability of fresh data.
      Moreover, a consumer may not wish (and it may even be infeasible)
      to subscribe to all of the channels belonging to a myriad of
      information providers that disseminate items of interest, either
      on demand (such as web, twitter, blogs and social networks), or
      tune to a broadcast channel (e.g., television, radio, newspaper).

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      In these cases, support should be provided to the consumer who
      would prefer obtaining the data based on descriptors such as
      keywords, tags, or other properties of the published data.

   o  Push enabled dissemination: The ability to exploit push-based
      delivery is a key to achieving timeliness and to avoid wasting
      server and network resources because of redundant polls.
      Therefore, an efficient pub/sub architecture must provide the
      capability for publishers to push information to online
      subscribers interested in it.  Such timely dissemination is
      necessary in many scenarios such as disaster (e.g., Tsunami)
      warnings, stock market information, news and gaming.

   o  Scalability: The target architecture should be able to accommodate
      a large number of subscribers as well as publishers (often
      subscribers are also publishers as user-generated content becomes
      common).  Therefore, it should minimize the amount of states
      maintained in the network, ensure the load on the publisher grows
      slowly (sublinearly) with the number of subscribers.  The load on
      the subscribers should also grow slowly with the number of
      publishers (e.g., dealing with the burden of duplicate
      elimination).  Importantly, the load on the network should not
      grow significantly with the growth in the number of publishers and
      subscribers.  There is also a need to accommodate a very large
      range in the amount of information that may be disseminated, and
      the need for all elements of the pub/sub framework in a content-
      centric environment to scale in a manageable way.

   o  Efficiency: The architecture should enable a nearly unlimited
      amount of information being generated by publishers, allow for
      delivery of information related to subscriptions independent of
      the frequency at which that information is generated by
      publishers.  The architecture must utilize network and server
      resources efficiently.  It is desirable that content is not
      transmitted multiple times by a server or on a link.  Furthermore,
      the overhead on publisher and subscriber end-points to query
      unnecessarily for information must be minimized.

   o  Dynamicity: The architecture should be able to deal with the
      substantial churn in subscription state, allowing a large number
      of users to join, leave and frequently change their subscriptions.
      The topics of interest may change frequently as well (e.g., in a
      Twitter-like publishing environment, where the popular topics
      change frequently).

   Additionally, to support a full-fledge pub-sub environment, it is
   desirable that the target system support the following additional

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   o  Support hierarchies and context in naming content: It is desirable
      to be able to exploit both context and hierarchies in identifying
      content.  Hierarchical naming has been recognized by NDN as well.
      Exploiting context enables a richer identification of content (in
      both subscriptions and published information), as noted in the
      database community.

   o  Support two-step dissemination for policy control and user
      interest: There is a need for pub/sub environments to support a
      two-step dissemination process both for reasons of policy and
      access control at the publisher as well as managing delivery of
      large volume content.  In such a scenario, the pub/sub framework
      would be designed to publish only a snippet of the data
      (containing a description of the content and the method how to
      obtain it) to subscribers.  The subscribers then request for the
      content based on their interest and allowance.

   o  Subscriber offline support: Another typical characteristic of pub-
      sub environments is that subscribers could be offline at the time
      the data is published.  There is clearly a need for asynchronous
      delivery of information in a pub/sub environment in an efficient,
      seamless and scalable manner.  The system needs to allow users who
      were online to retrieve the data that they have missed.  It should
      also allow new subscribers to retrieve previously published
      content that they are interested in.  We envisage a server that
      stores all the content published.

   o  Prevent Spam/DoS: Spam and DoS attacks are security issues that
      concern push based pub/sub mechanisms.  Efforts to mitigate this
      at the network layer as well as at the application layer should be

   Additionally, it will be desirable to have the following features to
   support a (limited) pub-sub environment in a disaster affected

   o  TBD

   o  TBD

5.  Related Work

5.1.  IP/Overlay Multicast

   IP multicast [RFC1112] is a candidate solution for efficiently
   delivering content to multiple receivers.  A sender sends data to a
   multicast group address that subscribers could join.  Multicast
   routing protocols such as PIM-SM [RFC4601] construct and maintain a

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   tree from each sender to all receivers of a multicast group.
   However, IP multicast isn't an efficient pub/sub delivery mechanism
   for several reasons: 1) IP multicast is designed for delivery of
   packets to connected end-points.  Dealing with disconnected operation
   (when subscribers are online) would have to be an application layer
   issue.  Overlay multicast solutions such as
   [Jannotti2000][Chu2002][Banerjee2002] are agnostic of the underlying
   network topology, usually relying on multiple unicasts in the
   underlay path and are therefore also inefficient as a pub/sub
   delivery mechanism. 2) The somewhat limited multicast group address
   space makes it difficult to support a direct mapping of CDs to IP
   multicast addresses. 3) Current IP multicast is not able to exploit
   relationships between information elements, such as CDs.  CDs may be
   hierarchical or may have a contextual relationship, which enables
   multiple CDs to be mapped to a group.  For example, consider a
   publisher that sends a message to all the subscribers interested in
   football, and subscribers who are interested in receiving messages
   about all sports.  The message from the publisher will have to be
   sent to two distinct IP multicast groups.  If there happens to be a
   subscriber of messages on sports and football, (s)he will receive the
   same message twice and will have to perform redundancy elimination in
   the application layer.  The result is a waste in network traffic and
   processing at both ends.

5.2.  Named-Data Networking (NDN)

   NDN has limited intrinsic support for pub/sub systems, a critical
   need in a content centric environment.  The aggregation of pending
   Interests at routers achieves efficient dissemination of information
   from NDN nodes.  But this aggregation is similar to a cache hit in a
   content distribution network (CDN) cache, which occurs only if
   subscribers send their Interests with some temporal locality.  Thus
   it avoids multiple Interest queries having to be processed directly
   by the content provider.  Note however that this is still a pull-
   based information delivery method and depends both on temporal
   locality of interests and a large enough cache to achieve effective
   caching in the (content centric) network.  On the other hand, native
   multicast support allows for a much more scalable push-based pub/sub
   environment, since it is not sensitive to issues such as the cycling
   of the cache when a large amount of information is disseminated.

   TBD: Update it based on recent modifications by the NDN team

5.3.  CCN

   TBD: Update it based on recent modifications by the CCN team

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5.4.  Content-Oriented Publish/Subscribe(COPSS)

   COPSS enhances CCN/NDN with a push-based delivery mechanism using
   multicast in a content-centric framework.  It is designed to satisfy
   the requirements mentioned above, especially to provide temporal
   separation between subscription (or expression of Interest) and
   publication.  At the content-centric network layer, COPSS uses a
   multiple-sender, multiple-receiver multicast capability, in much the
   same manner as PIM-SM.

5.5.  PSIRP Project


5.6.  NetInf Project (http://www.netinf.org)


5.7.  Pursuit Project (http://www.fp7-pursuit.eu/)


5.8.  Other Related Works

   Here we list the other related works we are considering.  The list
   might not be complete and we intend to add to it based on feedback
   received in further revisions.

   o  A.  Carzaniga, M.  Rutherford, A.  Wolf, A routing scheme for
      content-based networking, in: INFOCOM, 2004.

   o  B.  Segall, D.  Arnold, J.  Boot, M.  Henderson, T.  Phelps,
      Content Based Routing with Elvin, in: AUUG2K, 2000.

   o  C.  Esteve, F.  Verdi, M.  Magalhaes, Towards a new generation of
      information-oriented Internetworking architectures, in: ReArch,

   o  G.  Chockler, R.  Melamed, Y.  Tock, R.  Vitenberg, SpiderCast: a
      scalable interest-aware overlay for topic-based pub/sub
      communication, in: DEBS, 2007.

   o  H.  Eriksson, Mbone: the multicast backbone, Commun.  ACM 37 (8)
      (1994) 54-60.

   o  M.  Ott, L.  French, R.  Mago, D.  Makwana, Xml-based semantic
      multicast routing: an overlay network architecture for future
      information services, in: GLOBECOM, 2004.

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   o  P.  T.  Eugster, P.  A.  Felber, R.  Guerraoui, A.-M.  Kermarrec,
      The many faces of publish/subscribe, ACM Comput.  Surv. 35 (2)
      (2003) 114-131.

   o  R.  Baldoni, R.  Beraldi, V.  Quema, L.  Querzoni, S.  Tucci-
      Piergiovanni, TERA: topic-based event routing for peer-to-peer
      architectures, in: DEBS, 2007.

   o  R.  V.  Renesse, K.  P.  Birman, W.  Vogels, Astrolabe: A Robust
      and Scalable Technology for Distributed System Monitoring,
      Management, and Data Mining, ACM TOCS 21 (2001) 66-85.

   o  S.  Voulgaris, E.  Riviere, A.-M.  Kermarrec, M.  Van Steen, Sub-
      2-Sub: Self-Organizing Content-Based Publish and Subscribe for
      Dynamic and Large Scale Collaborative Networks, Research report,
      INRIA (December 2005).

   o  T.  Koponen, M.  Chawla, B.-G.  Chun, A.  Ermolinskiy, K.  H.
      Kim, S.  Shenker, I.  Stoica, A data-oriented (and beyond) network
      architecture, in: SIGCOMM, 2007.

   o  V.  Ramasubramanian, R.  Peterson, E.  G.  Sirer, Corona: a high
      performance publish-subscribe system for the world wide web, in:
      NSDI, 2006.

   o  V.  Jacobson, D.  K.  Smetters, J.  D.  Thornton, M.  F.  Plass,
      N.  H.  Briggs, R.  L.  Braynard, Networking Named Content, in:
      CoNEXT, 2009.

   o  Y.  Cui, B.  Li, K.  Nahrstedt, ostream: asynchronous streaming
      multicast in application-layer overlay networks, JSAC 22 (1)
      (2004) 91-106.

   o  Y.  Diao, S.  Rizvi, M.  J.  Franklin, Towards an internet-scale
      XML dissemination service, in: VLDB, 2004.

6.  Standardisation Considerations

   Future versions of this document will outline a concrete protocol
   specification for pub/sub support for ICN.  Below some initial
   standardisation considerations are outlined.

   An initial list of details that need to be specified is the

   o  Pub/Sub related interfaces/APIs

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   o  Pub/Sub related data structure modification to existing ICN

   We are also considering to write a survey paper that accumulates all
   the Pub/sub related work.

7.  References

7.1.  Normative References

   [RFC1112]  Deering, S., "Host extensions for IP multicasting", STD 5,
              RFC 1112, August 1989.

   [RFC4601]  Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,
              "Protocol Independent Multicast - Sparse Mode (PIM-SM):
              Protocol Specification (Revised)", RFC 4601, August 2006.

7.2.  Informative References

              Banerjee, S., Bhattacharjee, B., and C. Kommareddy,
              "Scalable application layer multicast", SIGCOMM, 2002, .

              Carzaniga, A., Papalini, M., and A. Wolf, "Content-based
              Publish/Subscribe Networking and Information-centric
              Networking", Proceedings of the ACM SIGCOMM workshop on
              Information-centric networking, ACM, 2011, .

              Chen, J., Arumaithurai, M., Fu, X., and K. Ramakrishnan,
              "COPSS: An Efficient Content Oriented Publish/Subscribe
              System", ACM/IEEE 7th Symposium on Architectures for
              Networking and Communications Systems (ANCS), 2011, .

              Chen, J., Arumaithurai, M., Fu, X., and K. Ramakrishnan,
              "G-COPSS: A Content Centric Communication Infrastructure
              for Gaming Applications", IEEE 32nd International
              Conference on Distributed Computing Systems (ICDCS), 2012,

   [Chu2002]  Chu, Y., Rao, S., Seshan, S., and H. Zhang, "A case for
              end system multicast", IEEE Journal on Selected Areas in
              Communications 20, no. 8 (2002): 1456-1471, .

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              Fenner, W., Rabinovich, M., Ramakrishnan, K., Srivastava,
              D., and Y. Zhang, "XTreeNet: Scalable overlay networks for
              XML content dissemination and querying (synopsis)", 10th
              International Workshop on Web Content Caching and
              Distribution (WCW), 2005, .

              Jannotti, J., Gifford, D., Johnson, K., and M. Kaashoek,
              "Overcast: reliable multicasting with on overlay network",
              Proceedings of the 4th conference on Symposium on
              Operating System Design & Implementation-Volume 4, pp.
              14-14. USENIX Association, 2000, .

              Katsaros, K., Xylomenos, G., and G. Polyzos, "MultiCache:
              An overlay architecture for information-centric
              networking", Computer Networks 55.4 (2011): 936-947, .

              Ramasubramanian, V., Peterson, R., and E. Sirer, "Corona:
              A High Performance Publish-Subscribe System for the World
              Wide Web", NSDI. Vol. 6. 2006, .

              Schmidt, T. and M. Waehlisch, "Why We Shouldn t Forget
              Multicast in Name-oriented Publish/Subscribe", arXiv
              preprint arXiv:1201.0349 (2012), .

Appendix A.  Acknowledgment

   This document has been supported by the GreenICN project (GreenICN:
   Architecture and Applications of Green Information Centric Networking
   ), a research project supported jointly by the European Commission
   under its 7th Framework Program (contract no. 608518) and the
   National Institute of Information and Communications Technology
   (NICT) in Japan (contract no. 167).  The views and conclusions
   contained herein are those of the authors and should not be
   interpreted as necessarily representing the official policies or
   endorsements, either expressed or implied, of the GreenICN project,
   the European Commission, or NICT.

Authors' Addresses

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   Mayutan Arumaithurai
   University of Goettingen
   Goldschmidt Str. 7
   Goettingen  37077

   Phone: +49 551 39 172046
   Fax:   +49 551 39 14416
   Email: arumaithurai@informatik.uni-goettingen.de

   Jiachen Chen
   University of Goettingen
   Goldschmidt Str. 7
   Goettingen  37077

   Phone: +49 551 39 172051
   Fax:   +49 551 39 14416
   Email: jiachen@informatik.uni-goettingen.de

   Xiaoming Fu
   University of Goettingen
   Goldschmidt Str. 7
   Goettingen  37077

   Phone: +49 551 39 172023
   Fax:   +49 551 39 14416
   Email: fu@informatik.uni-goettingen.de

   K. K. Ramakrishnan
   University of California, Riverside
   900 University Ave
   Riverside  CA 92521

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Internet-Draft                 ICN pub/sub                    March 2015

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