Time-aware publish/subscribe for delay-tolerant networks

1. Time-aware publish/subscribe for
delay-tolerant networks
Giuseppe Sollazzo
with Cecilia Mascolo and Mirco Musolesi
March-October 2006
Department of Computer Science
University College London

2. Outline
 Delay-tolerant networking
 Content dissemination in DTN
 Publish/subscribe
 Time and DTN
 Our approach: TACO-DTN
 Future work
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3. Delay-tolerant networks
 Networking in extreme environments
 IRTF Research Group
 Academic researchers
 Industrial entities
 Intel Research, Berkeley
 Spin-off of Interplanetary Internet project
 Bundle protocol
 Protocol and architecture specification
 RFC5050 (experimental, not Internet Standard)
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4. Why DTN?
 Provide interoperable connections in per-
formance-challenged networks
 Interspace communication
 Underwater communication
 Natural disasters, terrorism
 Developing world
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5. What does a DTN look like?
 Heterogeneous devices and
links
 Fixed hosts
 Mobile hosts
 “Random” mobility
 Known mobility pattern
 Intermittent connections
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6. Bundle protocol
 Main specification of DTN architecture
 Bundle nodes “register” at an endpoint
 Characteristics of the architecture
 Bundle = (fragments of) application data
 Behaviour of delivery
 No guarantee of end-to-end path
 Store-and-forward (Custody transfer)
 Decision made at application layer
 Convengence layer adapts it to network
 But what about routing?
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7. Content dissemination in DTNs
 Routing is not specified in the Bundle Protocol
 Each node may have its own routing procedure(s)
 Different approaches
 Forwarding-based vs. Replication-based
 Epidemic
 Spray-and-wait
 Probabilistic
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8. Publish/subscribe
 Subscriptions match publications based on
the concept of “interests”
 Topic-based
 Content-based
 Type-based
 Space-decoupling
 Time-decoupling
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9. Publish/subscribe and DTN
 Time decoupling
 Send a message, wait for someone to store and
forward it
 Hosts registration
 Similar to subscriptions mechanisms
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10. What about Time?
 “Delay” suggests time
 Scheduled encounters
 Mobility patterns
 Defining a new paradigm
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11. Time-aware publish/subscribe
 New model for DTN
 Goals
 Buffer management
 Event routing
 Target scenarios
 Just-in-time advertising
 Remote area connection
 Traffic news
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12. TACO-Dtn
 Our prototype of the model
 Content dissemination
 Topic-based publish/subscribe
 Temporal description of topics
 Discrete temporal functions
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13. TACO-Dtn
 Time-based event matching
 Temporal topic profiles: aggregate subscriptions data
(stored at servers)
 Temporal utility as selection metric
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14. Buffer management
Event routing
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15. Simulations
 Preliminary evaluations
 Mixed network topology
 Mobile hosts, fixed infostations, carriers
 Infostations as publishers
 Mobile nodes as subscribers
 Node mobility
 Group-based mobility
 We assume similar nodes will visit similar paths as in
probabilistic routing
 Other parameters
 Size: 1000m X 1000m
 Communication range: 100m (~802.11b)
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16. Simulations
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17. Future work
 Case-study
 Realistic simulations
 Use of mobility traces instead of patterns
 Applications needed!
 needed to validate the approach
 Java ME implementation
 portable
 Folksonomy-based publish/subscribe?
 Divergence metrics may help
 Space+time
 Using GIS
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18. References
Giuseppe Sollazzo, Mirco Musolesi and Cecilia Mascolo.
TACO-DTN: A Time-aware Content-based Dissemination System for Delay-
Tolerant Networks
In Proceedings of the 1st ACM SIGMOBILE International Workshop on Mobile
Opportunistic Networking (MobiOpp 2007). Colocated with Mobisys'07.
Puerto Rico, USA, June 2007. ACM Press.
http://www.dtnrg.org for further information about DTN
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