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Research Research overviewoverview
Koen Victor, Koen Victor, 12/200712/2007
12/2007 22
Topics Topics • Introduction
Goal of this work Two examples Problem description
• Approach Addressing scheme
• Design• Notation• Coupling with the Overlay Network• Mapping to the Overlay Network
Overlay network• Design & Structure• Functionality
Architecture• Related Work
Problem Problem • In an unstructured mobile network,
addressing data / devices / services is hard (objects): Name of the object Exact address in the network -> Implies knowledge the user may not have
• Much information that is available to the user cannot be used to address objects Contextual information Relational information
• When an object connects to a network, it needs to integrate in the existing infrastructure
12/2007 33
12/2007 44
Example: event in Yolande’s Example: event in Yolande’s agendaagenda
• Traditional way: synchronize via central server
Central Calender System
• Need exact address of CSS: Internet access
•Could both be online and available, but CSS offline
•Not known whether this is the best way to schedule a meeting
•Both need to synchronize to have the latest CSS information
Example: event in Yolande’s Example: event in Yolande’s agendaagenda
• Proposed way: context supported addressing
12/2007 55
• Where is Yolande?
•Does she have an agenda? Where is it?
•(How) Does she want to be notified now?
12/2007 66
Example: print on nearest Example: print on nearest printerprinter
• Traditional way: name printer using location
p2a-duplexp2a-slide
p1a
p4a
p3a
•Know the naming scheme
•Default printer is not always the closest
•Unavailable printer
12/2007 77
Example: print on nearest Example: print on nearest printerprinter
• Proposed way: context supported addressing
p2a-duplexp2a-slide
p1a
p4a
p3a
“Print this document on the printer that is closest to me”
Example: print on nearest Example: print on nearest printerprinter
• Proposed way: context supported addressing
• Several questions: Where is the person printing the document? What are the nearest printers? What of these printers are suitable? What of these are available?
• Alternative addresses:“Print this document on the printer that is closest to my desk”
12/2007 88
12/2007 99
Goal of this workGoal of this work• Address objects using
Specification of object features Specification of context of the object
• In an unstructured mobile network As seen by the user Possibly with gateways to Internet or other
networks User doensn’t deal with network related issues
• Facilitating: Knowing whether the object is addressable Knowing whether the object is available Communication via the real network address,
and higher level protocols• Meaning of address depends on its context
AdvantagesAdvantages• Meaning of address depends on context
<-> Fixed address may become invalid when context changes e.g. printer closest to me
• No knowledge of network, infrastructure, technical details, availability… necessary These parameters are filled in by contextual
information e.g. no obligatory calendar synchronization
• Depends on all interested parties: e.g. by both issuer and addressee Me: ‘printers nearest to me’ Sysadmin: ‘for which ‘me’ has access’
• One simple address specification may deal with a lot of contextual information and policies
12/2007 1010
12/2007 1111
Building blocksBuilding blocks• Address notation
Flexible enough to specify a variety of addresses Stringent enough to allow address checking and
avoid unnecessary ambiguity • Reasoning & Selection
What does the address mean? What is the relevant context information / policies
in the network?• Searching
Where to find the relevant context information? Where to find inference schemes to do reasoning?
• Structuring & Storing How to allow new objects to the network?
12/2007 1212
Topics Topics • Introduction
Goal of this work Two examples Problem description
• Approach Addressing scheme
• Design• Notation• Coupling with the Overlay Network• Mapping to the Overlay Network
Overlay network• Design & Structure• Functionality
Architecture• Related Work
12/2007 1313
Addressing SchemeAddressing Scheme
Design
Overlay network
1414
Addressing SchemeAddressing Scheme
Design
“Place a meeting in the agenda of Yolande”•Address is as simple as possible•Ambiguity: there may be several Yolandes
contextual parameters from the initiating application: Yolande of the research group
Complete the address with
•Ambiguity: there may be several of her devices with the calendar application
Complete the address withcontextual parameters from the network: where is she now? (synchronization is application dependent)
Addressing SchemeAddressing Scheme
12/2007 1515
“Place a meeting in the agenda of Yolande”•Address is as simple as possible•Ambiguity: are there preferences relating to scheduling of meetings? (phone, email, calendar, not now)
contextual parameters from the target: Right now, you should phone me
Complete the address with
Design The address is completed by context information: context supported addressing
12/2007 1616
Addressing SchemeAddressing Scheme
Notation
• Flexible enough to specify a variety of addresses
• Stringent enough to allow address checking and avoid unnecessary ambiguity
•Independent of technical details (network, availability)
•Independent of practical details (Location of the target, target’s preferences, …)
•Allows to ‘fill in’ contextual information
•Should be adaptable to the application’s type of requests
Addressing SchemeAddressing SchemeQuite intuitive:• Example address:
Agenda(a), <Yolande>.owns(a)
• Or more specific: Agenda(a), <Yolande>.owns(a), <Yolande>.headOf(<embedded>), <Yolande>.isMobile
• Other way of specifying this:Application(a), <Yolande>.supports(a), Application.type(a) == agenda
12/2007 1717
Notation example
Addressing SchemeAddressing SchemeAgenda(a), <Yolande>.owns(a)
• <term>: system looks up what it means, depending on context
• Additionally, you can be more specific:Person(term) : the term is of type person
• Instances:Person(<Yolande>) y, y.fullname(“Yolande Berbers”),y.headOf(<embedded>)
• If ‘embedded’ is not further specified, from the context (Yolande, Koen) the system can infer: embedded group
12/2007 1818
Notation example
12/2007 1919
Addressing SchemeAddressing Scheme
Coupling with the overlay network
• No explicit coupling with the overlay• However, the knowledge in the overlay
will determine the result of a request• Objects may be located but not able to
communicate• Objects may leave
• Therefore, there are 4 possible answers to a request:1. Network address / list of network
addresses2. Object not found, but address valid3. Object found, but not available4. Address not valid
12/2007 2020
Addressing SchemeAddressing Scheme
Mapping to the
overlay network
• Addresses can not be mapped directly to the overlay
• Search for objects and context specification used in the address using known search techniques• Inspect relations, compare to address• Search for context information needed
for the context reasoning
pda
phone
Second floor of CWPrinter p2a
CSS
Embedded Taskforce
12/2007 2121
Topics Topics • Introduction
Goal of this work Two examples Problem description
• Approach Addressing scheme
• Design• Notation• Coupling with the Overlay Network• Mapping to the Overlay Network
Overlay network• Design & Structure• Functionality
Architecture• Related Work
12/2007 2222
Overlay NetworkOverlay Network• Tasks:• Given a physical network network with
context aware devices: structure• Be able to provide one of the 4
answers• Optimize for searching
• Allow queries for every object or context information in the network
• Allow queries for associations between these objects or information (needed for reasoning)
• Connect & integrate new objects to the overlay
Fucti-onality
12/2007 2323
Overlay NetworkOverlay Network• Build as a semantic network, using
associations between both context and objects
• Associations Semantic, Temporal, Spatial, Procedural Examples
• Spatial: CloseTo(A,B, distance) with distance Exact(20,m) or Fuzzy(visible)
• Semantic: isInterface(Interface#4864, SonyBravia#4864)
• Temporal: UsageFrequency(5 times / day, average)• Procedural: isRemoteFor([Remote#12,Remote #6864],
Interface#4864) Object or context information points to other objects
or context using associations. Following these pointers is equal to navigating
through the network
Design &
structure
12/2007 2424
Overlay NetworkOverlay Network• Objects & context that has the same
association is grouped: context groups• Examples
5th floor in CW building (a) Printers in CW building (b) Computers with internet access (e) Objects that are accessed at least 2 times / minute
(c) All objects used by application X (d)
• Enpowers: Searching: (a) * (b) -> Printers on the 5th floor in
CW building Optimalisation: (c) * (d) -> Place all frequently
accessed objects near to application X Backup all objects used by X on another network (e)
Design &
structure
Overlay NetworkOverlay Network• Admission of objects / information to the
network Detect possible associations between the new
objects / information and the environment Make detected associations, join context
groups• Detection using adapted form of flooding:
context-aware flooding Format: object, distribution criteria,
max_hardhops, max_softhops Flooding bounded to relevant environment Reference to relevant objects is returned ->
possible association If object is relevant in large environment ->
new group candidate12/2007 2525
Design &
structure
12/2007 2626
ArchitectureArchitectureApplication Layer
Context Supported Addressing
Context Reasoning
Search Algorithms
Inference & Decision Engine
Overlay Network
Presence Management
Searching Algorithms
Optimalisation, QOS
Persistence Management
Network Layer
Routing QOS Connection Management