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Versions: 00 01 02 03 04                                                
COIN                                                          D. Trossen
INTERNET-DRAFT                                                    Huawei
Intended Status: Informational                          C. Sarathchandra
Expires: July 26, 2021                                 InterDigital Inc.
                                                             M. Boniface
                                               University of Southampton
                                                        January 26, 2021


          In-Network Computing for App-Centric Micro-Services
                 draft-sarathchandra-coin-appcentres-04


Abstract

   The application-centric deployment of 'Internet' services has
   increased over the past ten years with many millions of applications
   providing user-centric services, executed on increasingly more
   powerful smartphones that are supported by Internet-based cloud
   services in distributed data centres, the latter mainly provided by
   large scale players such as Google, Amazon and alike. This draft
   outlines a vision for evolving those data centres towards executing
   app-centric micro-services; we dub this evolved data centre as an
   AppCentre. Complemented with the proliferation of such AppCentres at
   the edge of the network, they will allow for such micro-services to
   be distributed across many places of execution, including mobile
   terminals themselves, while specific micro-service chains equal
   today's applications in existing smartphones.

   We outline the key enabling technologies that needs to be provided
   for such evolution to be realized, including references to ongoing
   standardization efforts in key areas.


Status of this Memo

   This Internet-Draft is submitted to IETF 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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   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."



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Table of Contents

   1   Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2   Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3   Use Cases  . . . . . . . . . . . . . . . . . . . . . . . . . .  4
   4   Requirements . . . . . . . . . . . . . . . . . . . . . . . . .  4
   5   Enabling Technologies  . . . . . . . . . . . . . . . . . . . .  5
     5.1  Application Packaging . . . . . . . . . . . . . . . . . . .  5
     5.2  Service Deployment  . . . . . . . . . . . . . . . . . . . .  7
     5.3  Compute Inter-Connection at Layer 2 . . . . . . . . . . . .  7
     5.4  Service Routing . . . . . . . . . . . . . . . . . . . . . .  8
     5.5  Constraint-based Forwarding Decisions . . . . . . . . . . .  9
     5.6  Collective Communication  . . . . . . . . . . . . . . . . . 10
     5.7  State Synchronization . . . . . . . . . . . . . . . . . . . 11
     5.8  Dynamic Contracts . . . . . . . . . . . . . . . . . . . . . 11
   6   Overview of Relevant Standardization Efforts . . . . . . . . . 11
   7   Security Considerations  . . . . . . . . . . . . . . . . . . . 12
   8   IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 12
   9   Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 12
   10  References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     10.1  Normative References . . . . . . . . . . . . . . . . . . . 13
     10.2  Informative References . . . . . . . . . . . . . . . . . . 13
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16





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1   Introduction

   With the increasing dominance of smartphones and application markets,
   the end-user experiences today have been increasingly centered around
   the applications and the ecosystems that smartphone platforms create.
   The experience of the 'Internet' has changed from 'accessing a web
   site through a web browser' to 'installing and running an application
   on a smartphone'. This app-centric model has changed the way services
   are being delivered not only for end-users, but also for business-to-
   consumer (B2C) and business-to-business (B2B) relationships.

   Designing and engineering applications is largely done statically at
   design time, such that achieving significant performance improvements
   thereafter has become a challenge (especially, at runtime in response
   to changing demands and resources). Applications today come
   prepackaged putting them at disadvantage for improving efficiency due
   to the monolithic nature of the application packaging. Decomposing
   application functions into micro-services [MSERVICE1] [MSERVICE2]
   allows applications to be packaged dynamically at run-time taking
   varying application requirements and constraints into consideration.
   Interpreting an application as a chain of micro-services, allows the
   application structure, functionality, and performance to be adapted
   dynamically at runtime in consideration of tradeoffs between quality
   of experience, quality of service and cost.

   Interpreting any resource rich networked computing (and storage)
   capability not just as a pico or micro-data centre, but as an
   application-centric execution data centre (AppCentre), allows
   distributed execution of micro-services. Here, the notion of an
   'application' constitutes a set of objectives being realized in a
   combined packaging of micro-services under the governance of the
   'application provider'. These micro-services may then be deployed on
   the most appropriate AppCentre (edge/fog/cloud resources) to satisfy
   requirements under varying constraints. In addition, the high degree
   of distribution of application and data partitions, and compute
   resources offered by the execution environment decentralizes control
   between multiple cooperating parties (multi-technology, multi-domain,
   multi-ownership environments). Furthermore, compute resource
   availability may be volatile, particularly when moving along the
   spectrum from well-connected cloud resources over edge data centres
   to user-provided compute resources, such as (mobile) terminals or
   home-based resources such as NAS and IoT devices.

   We believe that the emergence of AppCentreS will democratize
   infrastructure and service provision to anyone with compute resources
   with the notion of applications providing an element of governing the
   execution of micro-services. This increased distribution will lead to
   new forms of application interactions and user experiences based on



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   cooperative AppCentreS (pico-micro and large cloud data centres), in
   which applications are being designed, dynamically composed and
   executed.

2   Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

3   Use Cases

   Although our motivation for the 'AppCentre' term stems from the
   (mobile) application ecosystem, we foresee use cases that are not
   limited to mobile applications only. Instead, we interpret
   'applications' as a governing concept of executing a set of micro-
   services where the 'application provider' can reach from those
   realizing mobile applications over novel network applications to
   emerging infrastructure offerings serving a wide range of
   applications in a purpose- (and therefore application-)agnostic
   manner.

   Originally being described in more detail in this draft, use cases
   are now gathered and described in more detail in [COIN-usecases],
   following a common taxonomy for their description. Specifically, the
   use cases for immersive devices and infrastructure services have
   guided the following requirements and technology selection, although
   this draft also applies to a number of industrial use cases as well.
   For more detail on those use cases overall, we refer the reader to
   [COIN-usecases].

4   Requirements

   The following requirements are derived from the use cases in Section
   5 and 6 in [COIN-usecases], serving as a guidance for the following
   discussions on enabling technologies in Section 5 of this document.

   Req 1 - Service Routing: Any app-centric execution environment MUST
          provide means for routing of service requests between
          resources in the distributed environment.

   Req 2 - Constraint-based Forwarding Decisions: Any app-centric
          execution environment MUST provide means for dynamically
          choosing the best possible micro-service sequence (i.e.,
          chaining of micro-services) for a given application
          experience. Means for discovering suitable micro-service
          SHOULD be provided.




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   Req 3 - Flow Affinity: Any app-centric execution environment MUST
          provide means for pinning the excution of a specific micro-
          service to a specific resource instance in the distributed
          environment.

   Req 4 - Deployment: Any app-centric execution environment SHOULD
          provide means for packaging micro-services for deployments in
          distributed networked computing environments. The packaging
          SHOULD include any constraints regarding the deployment of
          service instances in specific network locations or compute
          resources. Such packaging SHOULD conform to existing
          application deployment models, such as mobile application
          packaging, TOSCA orchestration templates or tar balls or
          combinations thereof.

   Req 5 - Synchronization: Any app-centric execution environment MUST
          provide means for real-time synchronization and consistency of
          distributed application states.

   Req 6 - Generic Invocation: Any app-centric execution environment
          MUST provide support for app/micro-service specific invocation
          protocols.

   Req 7 - Collective Communication: Any app-centric execution
          environment SHOULD utilize Layer 2 multicast transmission
          capabilities for responses to concurrent service requests.

   Req 8 - Orchestration: Any app-specific execution environment SHOULD
          expose means to specify the requirements for the tenant-
          specific compute fabric being utilized for the app execution.
          Any app-specific execution environment SHOULD allow for
          dynamic integration of compute resources into the compute
          fabric being utilized for the app execution; those resources
          include, but are not limited to, end user provided resources.
          Any app-specific execution environment MUST provide means to
          optimize the inter-connection of compute resources, including
          those dynamically added and removed during the provisioning of
          the tenant-specific compute fabric. Any app-specific execution
          environment MUST provide means for ensuring availability and
          usage of resources is accounted for.


5   Enabling Technologies

   We now discuss a number of enabling technologies that address the
   requirements set out in Section 4.

5.1  Application Packaging



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   Applications often consist of one or more sub-elements (e.g., audio,
   visual, hepatic elements) which are 'packaged' together, resulting in
   the final installable software artifact. Conventionally, application
   developers perform the packaging process at design time, by packaging
   a set of software components as a (often single) monolithic software
   package, for satisfying a set of predefined application
   requirements.

   Decomposing micro-services of an application, and then executing them
   on peer execution points in AppCentreS (e.g., on an app-centric
   serverless runtime [SRVLESS]) can be done with design-time planning.
   Micro-service decomposition process involves, defining clear
   boundaries of the micro-service (e.g., using wrapper classes for
   handling input/output requests), which could be done by the
   application developer at design-time (e.g., through Android app
   packaging by including, as part of the asset directory, a service
   orchestration template [TOSCA] that describes the decomposed micro-
   services). Likewise, the peer execution points could be 'known' to
   the application (e.g., using well-known and fixed peer execution
   points on AppCentreS) and incorporated with the micro-services by the
   developer at design-time.

   Existing programming frameworks address decomposition and execution
   of applications centering around other aspects such as concurrency
   [ERLANG]. For decomposing at runtime, application elements can be
   profiled using various techniques such as dynamic program analysis or
   dwarf application benchmarks. The local profiler information can be
   combined with the profiler information of other devices in the
   network for improved accuracy. The output of such a profiler process
   can then be used to identify smaller constituting sub-components of
   the application in forms of pico-services, their interdependencies
   and data flow (e.g., using caller/callee information, instruction
   usage). Due to the complex nature of resulting application structure
   and therefore its increased overhead, in most cases, it may not be
   optimal to decompose applications at the pico level. Therefore, one
   may cluster pico-services into micro-services with common
   characteristics, enabling a meaningful (e.g., clustering pico-
   services with same resource dependency) and a performant
   decomposition of applications. Characteristics of micro-services can
   be defined as a set of concepts using an ontology language, which can
   then be used for clustering similar pico-services into micro-
   services. Micro-services may then be partitioned along their
   identified borders. Moreover, mechanisms for governance, discovery
   and offloading can be employed for 'unknown' peer execution points on
   AppCentreS with distributed loci of control.

   Therefore, with this app-centric model, application packaging can be
   done at runtime by constructing micro-service chains for satisfying



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   requirements of experiences (e.g., interaction requirements), under
   varying constraints (e.g., temporal consistency between multiple
   players within a shared AR/VR world)[SCOMPOSE]. Such packaging
   includes mechanisms for selecting the best possible micro-services
   for a given experience at runtime in the multi-technology
   environment. These run-time packaging operations may continuously
   discover the 'unknown' and adapt towards an optimal experience. Such
   decision mechanisms handle the variability, volatility and scarcity
   within this multi-X framework.

5.2  Service Deployment

   The service function chains, constituting each individual
   application, will need deployment mechanisms in a true multi-X
   (multi-user, multi-infrastructure, multi-domain) environment
   [SDEPLOY1][SDEPLOY2]. Most importantly, application installation and
   orchestration processes are married into one, as a set of procedures
   governed by device owners directly or with delegated authority.
   However, apart from extending towards multi-X environments, the
   process also needs to cater for changes in the environment, caused,
   e.g., by movement of users, new pervasive sensors/actuators, and
   changes to available infrastructure resources. Methods are needed to
   deploy service functions as executable code into chosen service
   execution points. Those methods need to support the various endpoint
   (e.g., device stacks, COTS stacks, etc.) and service function
   realizations, e.g., through utilizing existing and emerging
   virtualization techniques.

   A combination of application installation procedure and orchestrated
   service deployment can be achieved by utilizing the application
   packaging with integrated service deployment templates described in
   Section 5.1 such that the application installation procedure on the
   installing device is being extended to not only install the local
   application package but also extract the service deployment template
   for orchestrating with the localized infrastructure, using, for
   instance, REST APIs for submitting the template to the orchestrator.

   The concept of 'intent-based networking' [IB_CONC] has been the focus
   of studies in the Network Management RG, allowing for declaratively
   stating the goals that a network shall meet. In relation to service
   deployment, intent-based concepts may be useful for the placement of
   service endpoints in a distributed environment under given service-
   specific constraints, e.g., on HW constraints for the execution of
   service endpoints or similar. This could also link into conveying
   service-specific constraints for the forwarding of information, as
   discussed in the following Section 5.5.

5.3  Compute Inter-Connection at Layer 2



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   While Layer2 switching technologies have long proliferated in data
   centre deployments, recent developments have advanced the
   capabilities for interconnecting distributed computing resources over
   Layer2 technologies. For instance, the efforts in 3GPP on so-called
   '5G LAN' (or Vertical LAN) [SA2-5GLAN] allow for establishing a
   Layer2 bearer between participating compute entities, using a
   vertical-specific LAN identifier for packet forwarding between the
   distributed Layer2 entities. Combined with Layer2 technology in data
   centres as well as office and home networks alike, this enables the
   deployment of services in vertical (Layer2) networks, interconnecting
   with other Internet-based services through dedicated service
   gateways.

   Real deployments and realizations will have to show the scalability
   of this approach but it points into a direction where application or
   service-specific deployments could potentially 'live' entirely in
   their own vertical network, interconnecting only based on need (which
   for many services may not exist). From the application's or service's
   perspective, the available compute resource pool will look no
   different from that being realized in a single data centre albeit
   with the possibility to being highly distributed now among many
   (e.g., edge) data centres as well as mobile devices.

   In such a deployment, it is interesting to study the realization of
   suitable service routing capabilities, leading us to the next
   technology area of interest.

5.4  Service Routing

   Routing service requests is a key aspect within a combined compute
   and network infrastructure in order to enable true end-to-end
   experiences across distributed application execution points
   provisioned on distant cloud, edge and device-centric resources. Once
   the micro-services are packaged and deployed in such highly
   distributed micro-data centres, the routing mechanisms must ensure
   efficient information exchange between corresponding micro-services,
   e.g., at the level of service requests, within the multi-technology
   execution environment.

   Routing here becomes a problem of routing micro-service requests, not
   just packets, as done through IP. This calls for some form of 'flow
   affinity' that allows for treating several packets as part of a
   request semantic. This is important, e.g., for mobility (avoiding to
   send some packets of a larger request to one entity, while other
   packets are sent to another one, therefore creating incomplete
   information at both entities as a result). Also, when applying
   constraints to the forwarding of packets (discussed in more detail in
   Section 5.6), it is important to apply the actions across the packets



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   of the request rather than individually.

   Another key aspect is that of addressing services. Traditionally, the
   combination of the Domain Naming Service (DNS) and IP routing has
   been used for this purpose. However, the advent of virtualization
   with use cases such as those outlined in Section 3 (such as those on
   app-specific micro-services on mobile devices) have made it
   challenging to further rely on the DNS. Apart from the initial delay
   observed when resolving a service name into a locator for the first
   time, the long delay in updating DNS entries to 'point' to the right
   micro-service instances prohibits offloading to dynamically created
   service instances. If one was to use the DNS, one would be updating
   the DNS entries at a high rate, caused by the diversity of trigger,
   e.g., through movement. DNS has not been designed for such frequent
   update, rendering it useless for such highly dynamic applications.
   With many edge scenarios in the VR/AR space demanding interactivity
   and being latency-sensitive, efficient routing will be key to any
   solution.

   Various ongoing work on service request forwarding [RFC8677] with the
   service function chaining [RFC7665] framework as well as name-based
   routing [ICN5G][ICN4G][ICNIP] addresses some aspects described above
   albeit with a focus on HTTP as the main invocation protocol.
   Extensions will be required to support other invocation protocols,
   such as GRPC or MPI (for distributed AI use cases). Proposals such as
   those in [DYN-CAST] suggest extensions to the IP anycast scheme to
   enable the flexible routing of service requests to one or more
   service instances. Common to those proposals is the use of a semantic
   identifier, often a service identifier akin to a URL, in the routing
   decision within the network.

   Efforts existed in the IRTF, in the form of the Routing RG [RRG], to
   specifically study aspects of routing. The RRG concluded its work in
   2014, but its possible revival has been suggested in ongoing
   discussions on routing evolution [FIPE] as a forum to study semantic-
   rich routing approaches.

5.5  Constraint-based Forwarding Decisions

   Allocating the right resources to the right micro-services is a
   fundamental task when executing micro-services across highly
   distributed micro-data centres (e.g., resource management in cloud
   [CLOUDFED]). This is particularly important in the light of volatile
   resource availability as well as concurrent and highly dynamic
   resource access. Once the specific set of micro-services for an
   application has been identified, requirements (e.g., QoS) must be
   ensured by the execution environment. Therefore, all micro-data
   centres and the execution environment will need to realize mechanisms



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   for ensuring the utilization of specific resources within a pool of
   resources for a specific set of micro-services belonging to one
   application, while also ensuring integrity of the wider system.
   Application-layer solution frameworks, such as those developed as
   part of the Alto WG [ALTO], can be used for utilizing app/service-
   specific constraints.

   In relation to the service routing capability, realized below the
   application layer and discussed in the previous sub-section,
   constraints may need to be introduced into the forwarding decisions
   for service requests. Such constraints will likely go beyond network
   load and latency, as often applied in scenarios such as load
   balancing in CDNs and as used in solutions such as [RFC7868].
   Instead, those constraints could be app/service-specific and will
   need a suitable representation for the use within network nodes that
   are forwarding service requests, as also outlined in [DYN-CAST].
   Moreover, individual router decisions (e.g., realized through
   matching operations such as min/max/equal over a constraint
   representation) may be coordinated to achieve a distribution of
   service requests among many service instances, effectively realizing
   a service scheduling capability in the network, optimized around
   service-specific constraints, not unlike many existing data centre
   service switching schemes.

   As discussed already in Section 5.2, managing the constraints (for
   controlling the forwarding behaviour) may be linked into the concepts
   of intent-based networking [IB_CONC] to declaratively describe the
   goals of the forwarding or steering of traffic, while specific
   signaling protocols will need to be used to convey the actual
   constraints as well as the operations performed on them in order to
   fulfil the stated intent (or goals).

5.6  Collective Communication

   Many micro-service scenarios may exhibit some form of collective
   communication beyond 'just' unicast communication, therefore
   requiring support for 1:M, M:1, and M:N communication. It is
   important to consider here that such collective communication is
   often extremely short-lived and can even take place at the level of a
   single request, i.e., a following request may exhibit a different
   communication pattern, even at least a different receiver group for
   the same pattern, such as in the case of an interactive game. It is
   therefore required that solutions for supporting such collective
   communication must support the spontaneous formation of multicast
   relations, as observed in those scenarios.

   Solutions at Layer 2 have been discussed in [ICNIP], enabling the
   delivery of service requests over a Layer2 forwarding solution. The



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   solution in [BIER-MC] utilizes the capabilities introduced by the
   BIER multicast overlay [BIER] to form such spontaneous multicast
   relations. Both approaches, however, are limited to the reachability
   of the respective transport technology, i.e., the Layer 2 or BIER
   overlay. Solutions over Layer 3 are currently limited to long-lived
   IP multicast groups or will need to rely on application-level
   solutions, mapping the group communication to replicated unicast
   forwarding operations at the network layer, such as done in the
   message passing interface [MPI], leading to significant
   inefficiencies through high peak-to-average ratios for the required
   transport network deployments.

5.7  State Synchronization

   Given the highly distributed nature of app-centric micro-services,
   their state exchange and synchronization is a very crucial aspect for
   ensuring in-application and system wide consistency. Efforts such as
   those in [GAIA-X] aim at developing solutions for application areas
   such as distributed storage and data repositories. For this,
   mechanisms that ensure consistency will ensure that data is
   synchronized with different spatial, temporal and relational data
   within a given time period. From the perspective of support through
   in-network compute capabilities, such as provided through
   technologies like P4, it is important to consider what system and
   protocol support is required to utilize such in-network
   capabilities.

5.8  Dynamic Contracts

   NOTE: left for future revision

6   Overview of Relevant Standardization Efforts

  +--------------+--------------------------------------------------+
  | Requirement  | Standardization Efforts                          |
  +==============+==================================================+
  | 1-Service    | former Routing RG [RRG], possibly re-instated    |
  | Routing      | Dyncast [DYN-CAST]                               |
  |              | APN BoF [APN]                                    |
  +--------------+--------------------------------------------------+
  | 2-Constraint | Dyncast [DYN-CAST]                               |
  | based Fwd    | EIGRP [RFC7868]                                  |
  | Decision     | Alto WG [ALTO]                                   |
  |              | Intent-based Networking [IB_CONC]                |
  +--------------+--------------------------------------------------+
  | 3-Flow       | Dyncast [DYN-CAST]                               |
  | Affinity     |                                                  |
  +--------------+--------------------------------------------------+



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  | 4-Deployment | ETSI NFV MANO                                    |
  |              | Intent-based Networking [IB_CONC}                |
  +--------------+--------------------------------------------------+
  | 5-Synchroni- | GAIA-X [GAIA-X]                                  |
  | zation       |                                                  |
  +--------------+--------------------------------------------------+
  | 6-Generic    | Internet Services over ICN [ICNIP]               |
  | invocation   |                                                  |
  +--------------+--------------------------------------------------+
  | 7-Collective | BIER WG [BIER]                                   |
  | Communication| Internet Services over ICN (ICNIP]               |
  |              | Multicast for HTTP over BIER [BIER-MC]           |
  +--------------+--------------------------------------------------+
  | 8-Orchestr.  | 3GPP 5GLAN [SA2-5GLAN] and ETSI MANO             |
  +--------------+--------------------------------------------------+

     Figure 1: Mapping of Requirements to Standardization Efforts

7   Security Considerations

   The use of semantic (or service) identifiers for routing decisions,
   as mentioned in Section 5.4October 1, 2018April 4, 2019, requires
   methods to ensure the privacy and security of the communication
   through avoiding the exposure of service semantic (which is realized
   at the application layer) to the network layer, therefore opening up
   the opportunity for traffic inspection, among other things. The use
   of cryptographic information, e.g., through self-certifying
   identifiers, should be investigated to mitigate potential security
   and privacy risks.

8   IANA Considerations

   N/A

9   Conclusion

   This draft positions the evolution of data centres as one of becoming
   execution centres for the app-centric experiences provided today
   mainly by smart phones directly. With the proliferation of data
   centres closer to the end user in the form of edge-based micro data
   centres, we believe that app-centric experiences will ultimately be
   executed across those many, highly distributed execution points that
   this increasingly rich edge environment will provide, such as smart
   glasses and IoT devices. We have listed and discussed a number of
   enabling key technologies that address some of the challenges for
   realizing such AppCentre evolution.

   Based on the requirements relevant to those key technologies, derived



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   from the COIN use cases, we have further provided an evaluation of
   ongoing and related efforts in the relevant areas of study. We
   believe that this analysis can be useful for positioning work
   discussed and pursued in COIN against those ongoing efforts.
   Furthermore, it may guide those interested in the respective key
   technologies to create appropriate linkages to those ongoing efforts
   elsewhere.

10  References

10.1  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, DOI
              10.17487/RFC2119, March 1997, https://www.rfc-
              editor.org/info/rfc2119.

   [RFC7665]  Halpern, J., Ed., and C. Pignataro, Ed., "Service Function
              Chaining (SFC) Architecture", RFC 7665, DOI
              10.17487/RFC7665, October 2015, https://www.rfc-
              editor.org/info/rfc7665.

10.2  Informative References

   [MSERVICE1] Dragoni, N., Giallorenzo, S., Lafuente, A. L., Mazzara,
              M., Montesi, F., Mustafin, R., & Safina, L. (2017).
              Microservices: yesterday,today, and tomorrow. In Present
              and Ulterior Software Engineering (pp. 195-216). Springer,
              Cham.

   [MSERVICE2] Balalaie, A., Heydarnoori, A., & Jamshidi, P. (2016).
              Microservices architecture enables devops: Migration to a
              cloud-native architecture. IEEE Software, 33(3), 42-52.

   [SRVLESS]  C. Cicconetti, M. Conti and A. Passarella, "An
              Architectural Framework for Serverless Edge Computing:
              Design and Emulation Tools," 2018 IEEE International
              Conference on Cloud Computing Technology and Science
              (CloudCom), Nicosia, 2018, pp. 48-55. doi:
              10.1109/CloudCom2018.2018.00024

   [TOSCA]    Topology and Orchestration Specification for Cloud
              Applications Version 1.0. 25 November 2013. OASIS
              Standard. http://docs.oasis-
              open.org/tosca/TOSCA/v1.0/os/TOSCA-v1.0-os.html.

   [ERLANG]   Armstrong, Joe, et al. "Concurrent programming in ERLANG."
              (1993).



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   [SCOMPOSE] M. Hirzel, R. Soule, S. Schneider, B. Gedik, and R. Grimm,
              "A Catalog of Stream Processing Optimizations", ACM
              Computing Surveys,46(4):1-34, Mar. 2014

   [SDEPLOY1] Lu, H., Shtern, M., Simmons, B., Smit, M., & Litoiu, M.
              (2013, June). Pattern-based deployment service for next
              generation clouds. In 2013 IEEE Ninth World Congress on
              Services (pp. 464-471). IEEE.

   [SDEPLOY2] Eilam, T., Elder, M., Konstantinou, A. V., & Snible, E.
              (2011, May). Pattern-based composite application
              deployment. In 12th IFIP/IEEE International Symposium on
              Integrated Network Management (IM 2011) and Workshops (pp.
              217-224). IEEE.

   [RFC8677]  Trossen, D., Purkayastha, D., Rahman, A., "Name-Based
              Service Function Forwarder (nSFF) Component within a
              Service Function Chaining (SFC) Framework", RFC 8677,
              November 2019.

   [ICN5G]    Ravindran, R., Suthar, P., Trossen, D., Wang, C., White,
              G., "Enabling ICN in 3GPP's 5G NextGen Core Architecture",
              https://www.ietf.org/archive/id/draft-irtf-icnrg-5gc-icn-
              04, (work in progress), January 2021.

   [ICN4G]    Suthar, P., Jangam, Ed., Trossen, D., Ravindran, R.,
              "Native Deployment of ICN in LTE, 4G Mobile Networks",
              https://tools.ietf.org/html/draft-irtf-icnrg-icn-lte-4g-
              08, (work in progress), January 2021.

   [CLOUDFED] M. Liaqat, V. Chang, A. Gani, S. Hafizah Ab Hamid, M.
              Toseef, U. Shoaib, R. Liaqat Ali, "Federated cloud
              resource management: Review and discussion", Elsevier
              Journal of Network and Computer Applications, 2017.

   [GRPC]     High performance open source universal RPC framework,
              https://grpc.io/

   [MPI]      A. Vishnu, C. Siegel, J. Daily, "Distributed TensorFlow
              with MPI", https://arxiv.org/pdf/1603.02339.pdf

   [FCDN]     M. Al-Naday, M. J. Reed, J. Riihijarvi, D. Trossen, N.
              Thomos, M. Al-Khalidi, "fCDN: A Flexible and Efficient CDN
              Infrastructure without DNS Redirection of Content
              Reflection", https://arxiv.org/pdf/1803.00876.pdf

   [DYN-CAST] P. Liu, P. Willis, D. Trossen, "Dynamic-Anycast (Dyncast)
              Use Cases and Problem Statement",



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              https://tools.ietf.org/html/draft-liu-rtgwg-dyncast-ps-
              usecases-00, (work in progress), January 2021

   [SA2-5GLAN] 3gpp-5glan, "SP-181129, Work Item Description,
              Vertical_LAN(SA2), 5GS Enhanced Support of Vertical and
              LAN Services", 3GPP,
              http://www.3gpp.org/ftp/tsg_sa/TSG_SA/Docs/SP-181120.zip

   [COIN-usecases] I. Kunze, K. Wehrle, D. Trossen, "Use Cases for In-
              Network Computing", https://tools.ietf.org/html/draft-
              kunze-coin-industrial-use-cases-04, (work in progress),
              January 2021.

   [APN]      Application-Aware Networking (APN), IETF BoF,
              https://datatracker.ietf.org/group/apn/about/ (work in
              progress), January 2021.

   [RFC7868]  D. Davage et al. , "Cisco's Enhanced Interior Gateway
              Routing Protocol (EIGRP)", RFC 7868, May 2016,
              https://tools.ietf.org/html/rfc7868

   [ALTO]     Application-Layer Traffic Optimization, IETF Working
              Group, https://datatracker.ietf.org/wg/alto/about/,
              January 2021

   [GAIA-X]   Gaia-X, "GAIA-X: A Federated Data Infrastructure for
              Europe", accessed January 2021, https://www.data-
              infrastructure.eu/GAIAX/Navigation/EN/Home/home.html,
              January 2021

   [ICNIP]    D. Trossen, S. Robitzsch, M. Reed, M. Al-Naday, J.
              Riihijarvi, "Internet Services over ICN in 5G LAN
              Environments", https://tools.ietf.org/html/draft-trossen-
              icnrg-internet-icn-5glan-04, (work in progress), January
              2021

   [BIER-MC]  D. Trossen, A. Rahman, C. Wang, T. Eckert, "Applicability
              of BIER Multicast Overlay for Adaptive Streaming
              Services", https://tools.ietf.org/html/draft-ietf-bier-
              multicast-http-response-05, (work in progress), January
              2021

   [BIER]     Bit Indexed Explicit Replication, IETF Working Group,
              https://datatracker.ietf.org/wg/bier/about/, January 2021

   [RRG]     Routing RG (concluded), IRTF Research Group,
              https://trac.ietf.org/trac/irtf/wiki/RoutingResearchGroup,
              accessed January 2021



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   [FIPE]    Future Internet Protocol Evolution (FIPE) side meeting,
              https://github.com/FIPE-Study/IETF109-Side-Meeting-FIPE,
              November 2020

   [IB_CONC]  A. Clemm, L. Ciavaglia, L. Granville, J. Tantsura,
              "Intent-Based Networking - Concepts and Definitions",
              https://datatracker.ietf.org/doc/draft-irtf-nmrg-ibn-
              concepts-definitions/, (work in progress), September 2020

Authors' Addresses


   Dirk Trossen
   Huawei Technologies Duesseldorf GmbH
   Riesstr. 25C
   80992 Munich
   Germany

   Email: Dirk.Trossen@Huawei.com



   Chathura Sarathchandra
   InterDigital Europe, Ltd.
   64 Great Eastern Street, 1st Floor
   London EC2A 3QR
   United Kingdom

   Email: Chathura.Sarathchandra@InterDigital.com


   Michael Boniface
   University of Southampton
   University Road
   Southampton SO17 1BJ
   United Kingdom

   Email: mjb@it-innovation.soton.ac.uk













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