A Parameter-Based Service Discovery Protocol for Mobile Ad-Hoc Networks

A Parameter-Based Service Discovery Protocolfor Mobile Ad-Hoc Networks

Unai Aguilera and Diego [email protected]

DeustoTech - Deusto Institute of Technology, University of DeustoBilbao, Spain

http://www.morelab.deusto.es

July 10, 2012

[email protected]

http://www.morelab.deusto.es

Outline

Introduction

Overview

Taxonomy usage

Search

Conclusions

ADHOC-NOW 2012, Belgrade, Serbia 2 / 20

Motivation

I MANET of devices providing services.I Devices connect/disconnectI No central information managerI Service Oriented Applications⇒ Service DiscoveryI Current solutions

I Search using service identifiers or service typeI Not suitable when searching for functional properties

I Service CompositionI Create service work-flows to provide new functionalities to the

users.I Discover compatible services (Input/Output).

ADHOC-NOW 2012, Belgrade, Serbia Introduction 3 / 20

Parameter-based Service Discovery

I Services are located using their input/output parametersI I/O parameters are classified

I Taxonomy of conceptsI Parameter disseminationI Service search and route managementI Other elements

I Neighbour detection⇒ using periodic beacon messages.I Reliable broadcast⇒ ACK messages

ADHOC-NOW 2012, Belgrade, Serbia Overview 4 / 20

Parameter dissemination

I Each node mantains a Parameter tableI The higher the value⇒ the closer a parameter of that type.I Local parameters Dd (max. dissemination value).I Real distance (hops) = Dd - value.I Decremented with each hop until it reaches 0.


Parameter table

I Defined as a table of {P,L} pairs.I P ⇒ parameter type.I L⇒ list of elements (D,N). Multiple Paths

I D ⇒ disseminated distance value.I N ⇒ neighbour (e.g network address) which supplied the

information. Avoid back-propagation.I Proactive algorithm

I Dissemination starts on nodes with services.I New neighbour detection⇒ broadcast parameter table.I Neighbour disappears⇒ remove entries received from that

node.I Updates are propagated across the network.


Updates propagation

I Changes are propagated to neighbours using UpdateTablemessages.

I Deletions⇒ list of entries which must be removed fromreceiver’s tables.

I Additions⇒ contains new information to be added.I Nodes apply received updatesI Changes are incremental. Reliable broadcast needed.I If changes occur in a node parameter table⇒ continue prop

agation. ExceptI Maximum dissemination distance reached.I No more values to delete.


Taxonomy and parameter grouping

I Pre-shared taxonomy relates the types of disseminatedservice’s parameters

I Expressed in XMLSchema, RDF or OWL.I Let A and B be two different parameters

I Equality occurs when their type is equal.I Subsumption means that A has a more general type than B.I Not-related if none of previous conditions occurs.

I Parameter groupingI A group represents all those parameters related through

equality or subsumption relationships.I Parameter tables are grouped during dissemination.

I Reduce the number of broadcasted messages.I Most general concept. (A and B as A)I Highest value.

ADHOC-NOW 2012, Belgrade, Serbia Taxonomy usage 8 / 20

Neighbour detection

I Protocol is proactive.I Disseminates and maintains parameter information.I Searches are hold until explictly cancelled.

I Reaction to network mobility needed.I Usage of periodic beacon messages.

I Table of known neighbours.I Nodes send beacons with a period TbI Expiration time T ≥ 2 ∗ Tb

I Any message acts as beacon message.I Neighbour updates are notified with an small delay.


Reliable broadcast

I IEEE802.11 does not avoid hidden terminal/collisions.I Proposed dissemination uses incremental changes.I Reliable broadcast

I List of expected destinations.I 1-hop neighbours reply with an ACK message.I Messages will be repeated until correctly received.I Random time for rebroadcast.

I To reduce number of broadcasted messages.I Multiple messages⇒ one single broadcast.


Taxonomy propagation

I A subsumes BI New nodes appear


Taxonomy propagation

I A subsumes BI Network breaks


Experiments configuration

I Simulated with NS-2 + AgentJ (Java 1.6 implementation).I 100 nodes.I 700x700 area.I Transmission range 100 m.I IEEE802.11 as MAC protocol.I 11 Mb/s and MTU 1500 bytes.I Maximum dissemination distance 10 hops.I Random WaypointI Speed 0-5 m/s. Pause time: 50, 100 s.

I This scenario has1

I Average Network Partition ≤ 5%I Average Shortest Path = 4.15 hops

1Kurkowski, S., Navidi, W., Camp, T.: Constructing MANET simulationscenarios that meet standards. In: IEEE Intl. Conf. on Mobile Adhoc andSensor Systems. pp. 1–9 (2007)


Dissemination experiment

I 2 to 20 services deployed with and without replication.


Service search

I Service search is started by sending a SearchMessageI Types of service’s parameters to locate.I Propagation controlled using a TTL.I Flooded⇒ Unique search ID.I Active until explicitly cancelled.

I Two search types:I Exact : I/O parameters of the same exact type are located.I Generic: exact and subsumed types are located.

I Node accepts a search message⇒ SearchResponsemessage is sent to searching node.

I Using unicast routes created during the propagation of searchmessages.

I Response message also create unicast routes.I Route tables are updated during mobility.

ADHOC-NOW 2012, Belgrade, Serbia Search 15 / 20

Search pruning

I Search is propagated only if:I TTL ≥ (Dd − v).I v is obtained from the parameter table

I Meaning that:I Near compatible parameters exist.I Can be reached with the current search message TTL.


Search experiment

I 30 services randomly distributed with 6 parameters each one.I Searches performed each 5 seconds. Groups of 5 nodes.I 10 seconds until search cancelled.

a)

c) d)

b)


Conclusions

I Protocol for service discovery proposed and tested.I Situations where a functional search is required (e.g service

composition).I Two parts:

I DisseminationI Disseminates service I/O parameters instead of service type or

id.I Uses taxonomy information to group paramaters and decrease

the number of messages.I Service search

I Performs pruning based on disseminated information to reducemessage overhead.

ADHOC-NOW 2012, Belgrade, Serbia Conclusions 18 / 20

Future work

I Generalize proposed protocol to propagate and search anykind of information, not only service parameters.

I Propagation of taxonomies through ad hoc network avoidinga pre-shared one.


Questions?

Thank you!


A Parameter-Based Service Discovery Protocol for Mobile Ad-Hoc Networks

Technology

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