Time-aware publish/subscribe for delay-tolerant networks

Giuseppe Sollazzowith Cecilia Mascolo and Mirco Musolesi

March-October 2006Department of Computer Science

University College London

Outline

Delay-tolerant networking Content dissemination in DTN

Publish/subscribe Time and DTN Our approach: TACO-DTN Future work

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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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Why DTN?

Provide interoperable connections in per-formance-challenged networks

Interspace communication Underwater communication Natural disasters, terrorism Developing world

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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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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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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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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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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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What about Time?

“Delay” suggests time Scheduled encounters Mobility patterns Defining a new paradigm

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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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TACO-Dtn

Our prototype of the model Content dissemination

Topic-based publish/subscribe Temporal description of topics

Discrete temporal functions

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TACO-Dtn Time-based event matching Temporal topic profiles: aggregate subscriptions data

(stored at servers) Temporal utility as selection metric

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Buffer management Event routing

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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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Simulations

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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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ReferencesGiuseppe 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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