6lowapp R. Gold
Internet-Draft S. Krco
Intended status: Informational Ericsson
Expires: April 22, 2010 A. Gluhak
University of Surrey
Z. Shelby
Sensinode
October 19, 2009
SENSEI 6lowapp Requirements
draft-gold-6lowapp-sensei-00
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Abstract
This draft examines the requirements created by the SENSEI project
which are relevant to the 6LowApp interest group. The SENSEI project
is a large-scale EU project dealing with the design and
implementation of a framework for supporting applications wishing to
use sensor information.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Markets and Scenarios . . . . . . . . . . . . . . . . . . . . . 5
3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. General . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2. Application Protocols . . . . . . . . . . . . . . . . . . . 7
3.3. Application Commissioning . . . . . . . . . . . . . . . . . 8
4. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 9
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1. Normative References . . . . . . . . . . . . . . . . . . . 9
8.2. Informative References . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9
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1. Introduction
In order to fully realize the vision of intelligent machine-to-
machine (M2M) communication, heterogeneous wireless sensor and
actuator networks (WS&AN) have to be integrated into a common
framework of global scale on the Internet. This framework will need
to make the resources of the WS&ANs available to services and
applications via a set of open service interfaces. The SENSEI
project is a large European Union Framework 7 project started in 2008
with a consortium of 19 partners [SENSEI]. This project has created
an open architecture that fundamentally addresses the scalability
problems for a large number of globally distributed WS&AN devices.
It provides necessary network and information management services to
enable reliable and accurate context information retrieval and
interaction with the physical environment. By adding mechanisms for
accounting, security, privacy and trust it enables an open and secure
environment for context-awareness and real world interaction.
The SENSEI Framework represents sensors and actuators as resources.
A Resource is a conceptual representation, in the SENSEI domain, of
any information source that enables real world sensing or has the
ability to act upon the environment and entities within it. In
addition to Resources that have direct access to the physical world,
the concept covers also indirect information sources that acquire
context information via aggregation, fusion or even inference from
other SENSEI Resources. The SENSEI Framework has been designed using
fundamental concepts of the World-Wide Web. In order to enable the
SENSEI framework on even the most constrained devices (simple
sensors) and networks (such as 6LoWPAN [RFC4944]), it makes use of a
SENSEI embedded resource concept extending the web resource model to
minimal IPv6 nodes with very little overhead.
SENSEI project has made the initial implementation of the designed
global framework. It consists of the SENSEI core components: -
Resource Directory: serving as a rendez-vous point for resources and
resource users, it is storing descriptions of all available
resources. XML is used to describe the resources. There are two
types of description: basic and advanced. The basic descriptions
contain simple text based tags identifying the resource. Advanced
resource descriptions contain semantic descriptions with detailed
information about the context of the resource including its location,
available operations, inputs, outputs, etc. All resource
descriptions are XML based. - Semantic Query Resolver: Responsible
for analysis of high level user queries and discovery of suitable and
available resources capable of providing information required to
respond to the queries - Wireless sensor and actuator network islands
that interact with the framework via their respective gateways.
Implementation of a SENSEI resource end point wrapper is provided and
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can be applied to any gateway to make it SENSEI compliant.
Communication between all framework components is implemented using
RESTful interfaces. POST, GET, UPDATE and DELETE messages are used
to implement defined interfaces: RPI (Resource Publication
Interface), RLI (Resource Lookup interface) and RAI (Resource Access
Interface). WS&AN Gateways are responsible for compression of these
messages for the end sensor nodes using EXI.
The SENSEI project has very similar goals to 6LowApp
[I-D.bormann-6lowpan-6lowapp-problem], and has considered a wide
range of M2M applications. This document introduces selected markets
and scenarios that SENSEI is addressing and the requirements which
have been derived from them for achieving the SENSEI resource
architecture. We especially look at the SENSEI embedded resource
concept, and the requirements related to that useful also in the
scope of 6LowApp. Finally the document concludes with possible
contributions to the 6LowApp effort.
2. Markets and Scenarios
A large effort has been made in SENSEI to identify and study relevant
markets and application scenarios for this technology. In this
section we look at a subset of these applications.
Transportation: Modern cars along with the roads are becoming more
instrumented with sensors. Taking information from these different
sources and presenting it to the driver and/or passengers of a car
would allow better navigation and safety. Collision avoidance
systems and monitoring of transportation of hazardous materials are
two typical examples. Governmental authorities would also benefit
from more accurate information about road traffic patterns for
planning purposes. Enterprises, such as freight companies, would be
able to perform more effective route optimization which allows energy
savings.
Smart places: The major issues of the future have to be tackled in
cities: environment, security and well-being. To meet these needs,
sensors and actuators will thrive preferably there thanks to
economies of scale. This will take the form of mapping the physical
space into the Internet by allowing the public to interact, locally
or remotely, with the physical environment through the Internet via
the use of mobile devices.
Building automation: Every building (houses, offices etc.) will have
wireless sensor and actuator networks in order to automate some
processes, to support in users' activities, to make people more
comfortable and to secure their environment through more efficient
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energy consumption. There is a critical opportunity for deploying
Sin's in every building. In addition to the standard WS&AN
applications like the monitoring of temperature, humidity and other
parameters in a certain area or room, applications improving energy
management are of increasing importance.
Supply chain management: Whilst SENSEI examines passenger transport,
supply chain management is an equally important area focusing on
goods transport. As for passenger transport mobility is a key issue
for future for goods transport as well, because supply chains are
getting ever more global. In particular for cross border shipments,
companies have to stick to regulations imposed by external
authorities, environmental or social regulations.
3. Requirements
Using the application scenarios identified for the project,
requirements were extracted for achieving the global resource
architecture of the project. In this section the general project
requirements are first summarized. This is followed by an analysis
of technical requirements related to realizing the SENSEI embedded
resource concept that will be of interest to 6LowApp.
3.1. General
General requirements that have been derived from the SENSEI scope and
problem statement are as follows:
(1) Horizontalisation: Facilitate the horizontal reuse of sensing,
actuation and processing resources for a large number of
applications. This is similar to the idea of software reuse in
software engineering. Rather than having to recreate custom
bespoke solutions from scratch, it would be more efficient to
reuse the existing infrastructure.
(2) Heterogeneity: Accommodate a variety of different (technology,
administrative domains) sensor and actuator networks at its
edges. Whilst there will undeniably be an enormous variety of
sensors and actuators in the future, it is essential to use a
common method for interacting with them.
(3) Reduced Complexity: Reduce the complexity of accessing sensing
and actuation resources for applications. Since many sensors &
actuators and even gateways will have limited hardware
resources, keeping the complexity to an absolute minimum will be
crucial for the successful operation of the system.
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(4) Simplicity: Reduce the barrier of participation for WS&ANs and
thus facilitate deployment by ease of integration. Related to
the previous point, it is important that it is simple and
straightforward for new WS&ANs to be connected to a SENSEI
system and for these resources to be easily accessible.
(5) Evolvability: The architecture must be evolvable to withstand
technological change forced upon by tussles carried out by
actors in the eco-system. For reasons of sustainability we wish
to maximize the lifetime of the deployed system by allowing it
to be retasked to support new sensors and also new applications.
3.2. Application Protocols
The SENSEI project has designed and implemented an embedded web
resource protocol with similar goals to that of 6LowApp. In this
section we have extracted the key requirements used for this design.
In the realization of SENSEI resources and components, their
interfaces have been designed using RESTful principles.
Application protocol requirements from SENSEI:
(1) Push & Pull methods of interaction need to be supported.
Additionally, both one-time and periodic versions of these
interaction methods need to be supported to support as wide a
range of interactions as possible. As sensor nodes are often
available with a small duty cycle, a subscription-based PUSH
feature is critical to the application protocol. It should be
noted here that push interaction without any optimization is
quite resource-intensive as it requires soft-state to be kept at
the resource as to who the subscribers are.
(2) URL identifiers for resources, with the ability to compress URLs
with out-of-band identifiers.
(3) Caching and the ability to deal with sleeping nodes at the edge
of IP sensor network (e.g. 6LoWPAN) islands.
(4) Support for REST methods (GET, POST, PUT, DELETE) allowing for
easy interoperability with HTTP through a proxy.
(5) Support for UDP as a transport. Wireless mesh networks suffer
from packet losses and SENSEI transactions are often just a
single packet exchange. TCP is not suitable in such situations
due to its sensitivity to large variations in latency which are
typical of wireless cellular networks and also keeping a TCP
connection up in the presence of mobility is a challenging task.
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(6) Internet media type and transfer encoding type support. The
project uses RDF/XML and XML payloads which are encoded using
EXI.
(7) A compact protocol header which is easy to parse.
3.3. Application Commissioning
SENSEI performs application commissioning using what is called the
Resource Publication Interface (RPI). This interface is realized
with the same embedded web resource protocol on a well-known URL on
the proxy (usually on the Edge Router of the WS&AN) supporting REST
methods. Embedded resources advertise themselves by sending an EXI
encoded XML resource description, describing its resources available,
the interfaces to access them and meta-data.
Once resources have been published, they can subsequently be looked
up by using the corresponding Resource Lookup Interface (RLI). The
RLI supports both one-shot lookups and longer-lasting lookup
subscriptions. Similar to the RPI above, it uses an embedded web
resource protocol to provide this functionality.
The only requirement this kind of application commissioning requires
is for the embedded web protocol to support URLs and standard content
and encoding types. For more general use multicast support may also
be required.
4. Conclusions
The SENSEI project has developed an architecture for globally
scalable web resources for machines, sensors and actuators - The
Internet of Things. Part of this architecture includes an embedded
resource concept enabling web resources on very constrained devices
and networks while maintaining end-to-end IP principles and easy
interoperability with existing web protocols.
Potential contributions of this consortium to the 6LowApp effort may
include:
(1) Input to the problem statement, objectives and requirements
(2) Participation in the design of an embedded web resource protocol
(3) Participation in the requirements and design of application
commissioning
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(4) Possible input on security, web architecture integration,
scalability and resource mobility.
5. Security Considerations
No security issues have been identified in this draft.
6. IANA Considerations
This draft requires no IANA consideration.
7. Acknowledgments
We wish to thank our fellow members of the SENSEI consortium for many
fruitful discussions.
8. References
8.1. Normative References
[I-D.bormann-6lowpan-6lowapp-problem]
Bormann, C., Sturek, D., and Z. Shelby, "6LowApp: Problem
Statement for 6LoWPAN and LLN Application Protocols",
draft-bormann-6lowpan-6lowapp-problem-01 (work in
progress), July 2009.
[RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
"Transmission of IPv6 Packets over IEEE 802.15.4
Networks", RFC 4944, September 2007.
8.2. Informative References
[SENSEI] The SENSEI Work Package 3 team, "Reference Architecture",
Deliverable 3.2, 12 2008, <SENSEI>.
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Authors' Addresses
Richard Gold
Ericsson
Faeroegatan 6
Kista 16480
Sweden
Phone: +46 76 11 53 725
Email: richard.gold@ericsson.com
Srdjan Krco
Ericsson
Milana Savica 60
Novi Sad N/A
Serbia
Phone: +38163531683
Email: srdjan.krco@ericsson.com
Alex Gluhak
University of Surrey
University of Surrey
Guildford GU2 7XH
UK
Phone: +44 1483 689124
Email: a.gluhak@surrey.ac.uk
Zach Shelby
Sensinode
Kidekuja 2
Vuokatti 88600
FINLAND
Phone: +358407796297
Email: zach@sensinode.com
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