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

A Parameter-Based Service Discovery Protocol for Mobile Ad-Hoc Networks ´ ˜ Unai Aguilera and Diego Lopez-de-Ipina unai.aguilera@deusto.es DeustoTech - Deusto Institute of Technology, University of Deusto Bilbao, Spain http://www.morelab.deusto.es July 10, 2012

Outline Introduction Overview Taxonomy usage Search ConclusionsADHOC-NOW 2012, Belgrade, Serbia 2 / 20

Motivation MANET of devices providing services. Devices connect/disconnect No central information manager Service Oriented Applications ⇒ Service Discovery Current solutions Search using service identiﬁers or service type Not suitable when searching for functional properties Service Composition Create service work-ﬂows to provide new functionalities to the users. Discover compatible services (Input/Output).ADHOC-NOW 2012, Belgrade, Serbia Introduction 3 / 20

Parameter-based Service Discovery Services are located using their input/output parameters I/O parameters are classiﬁed Taxonomy of concepts Parameter dissemination Service search and route management Other elements Neighbour detection ⇒ using periodic beacon messages. Reliable broadcast ⇒ ACK messagesADHOC-NOW 2012, Belgrade, Serbia Overview 4 / 20

Parameter dissemination Each node mantains a Parameter table The higher the value ⇒ the closer a parameter of that type. Local parameters Dd (max. dissemination value). Real distance (hops) = Dd - value. Decremented with each hop until it reaches 0.ADHOC-NOW 2012, Belgrade, Serbia Overview 5 / 20

Parameter table Deﬁned as a table of {P, L} pairs. P ⇒ parameter type. L ⇒ list of elements (D, N). Multiple Paths D ⇒ disseminated distance value. N ⇒ neighbour (e.g network address) which supplied the information. Avoid back-propagation. Proactive algorithm Dissemination starts on nodes with services. New neighbour detection ⇒ broadcast parameter table. Neighbour disappears ⇒ remove entries received from that node. Updates are propagated across the network.ADHOC-NOW 2012, Belgrade, Serbia Overview 6 / 20

Updates propagation Changes are propagated to neighbours using UpdateTable messages. Deletions ⇒ list of entries which must be removed from receiver’s tables. Additions ⇒ contains new information to be added. Nodes apply received updates Changes are incremental. Reliable broadcast needed. If changes occur in a node parameter table ⇒ continue prop agation. Except Maximum dissemination distance reached. No more values to delete.ADHOC-NOW 2012, Belgrade, Serbia Overview 7 / 20

Taxonomy and parameter grouping Pre-shared taxonomy relates the types of disseminated service’s parameters Expressed in XMLSchema, RDF or OWL. Let A and B be two different parameters Equality occurs when their type is equal. Subsumption means that A has a more general type than B. Not-related if none of previous conditions occurs. Parameter grouping A group represents all those parameters related through equality or subsumption relationships. Parameter tables are grouped during dissemination. Reduce the number of broadcasted messages. Most general concept. (A and B as A) Highest value.ADHOC-NOW 2012, Belgrade, Serbia Taxonomy usage 8 / 20

Neighbour detection Protocol is proactive. Disseminates and maintains parameter information. Searches are hold until explictly cancelled. Reaction to network mobility needed. Usage of periodic beacon messages. Table of known neighbours. Nodes send beacons with a period Tb Expiration time T ≥ 2 ∗ Tb Any message acts as beacon message. Neighbour updates are notiﬁed with an small delay.ADHOC-NOW 2012, Belgrade, Serbia Taxonomy usage 9 / 20

Reliable broadcast IEEE802.11 does not avoid hidden terminal/collisions. Proposed dissemination uses incremental changes. Reliable broadcast List of expected destinations. 1-hop neighbours reply with an ACK message. Messages will be repeated until correctly received. Random time for rebroadcast. To reduce number of broadcasted messages. Multiple messages ⇒ one single broadcast.ADHOC-NOW 2012, Belgrade, Serbia Taxonomy usage 10 / 20

Taxonomy propagation A subsumes B New nodes appearADHOC-NOW 2012, Belgrade, Serbia Taxonomy usage 11 / 20

Taxonomy propagation A subsumes B Network breaksADHOC-NOW 2012, Belgrade, Serbia Taxonomy usage 12 / 20

Experiments conﬁguration Simulated with NS-2 + AgentJ (Java 1.6 implementation). 100 nodes. 700x700 area. Transmission range 100 m. IEEE802.11 as MAC protocol. 11 Mb/s and MTU 1500 bytes. Maximum dissemination distance 10 hops. Random Waypoint Speed 0-5 m/s. Pause time: 50, 100 s. This scenario has1 Average Network Partition ≤ 5% Average Shortest Path = 4.15 hops 1 Kurkowski, S., Navidi, W., Camp, T.: Constructing MANET simulation scenarios that meet standards. In: IEEE Intl. Conf. on Mobile Adhoc and Sensor Systems. pp. 1–9 (2007)ADHOC-NOW 2012, Belgrade, Serbia Taxonomy usage 13 / 20

Dissemination experiment 2 to 20 services deployed with and without replication.ADHOC-NOW 2012, Belgrade, Serbia Taxonomy usage 14 / 20

Service search Service search is started by sending a SearchMessage Types of service’s parameters to locate. Propagation controlled using a TTL. Flooded ⇒ Unique search ID. Active until explicitly cancelled. Two search types: Exact: I/O parameters of the same exact type are located. Generic: exact and subsumed types are located. Node accepts a search message ⇒ SearchResponse message is sent to searching node. Using unicast routes created during the propagation of search messages. Response message also create unicast routes. Route tables are updated during mobility.ADHOC-NOW 2012, Belgrade, Serbia Search 15 / 20

Search pruning Search is propagated only if: TTL ≥ (Dd − v ). v is obtained from the parameter table Meaning that: Near compatible parameters exist. Can be reached with the current search message TTL.ADHOC-NOW 2012, Belgrade, Serbia Search 16 / 20

Search experiment 30 services randomly distributed with 6 parameters each one. Searches performed each 5 seconds. Groups of 5 nodes. 10 seconds until search cancelled. a) b) c) d)ADHOC-NOW 2012, Belgrade, Serbia Search 17 / 20

Conclusions Protocol for service discovery proposed and tested. Situations where a functional search is required (e.g service composition). Two parts: Dissemination Disseminates service I/O parameters instead of service type or id. Uses taxonomy information to group paramaters and decrease the number of messages. Service search Performs pruning based on disseminated information to reduce message overhead.ADHOC-NOW 2012, Belgrade, Serbia Conclusions 18 / 20

Future work Generalize proposed protocol to propagate and search any kind of information, not only service parameters. Propagation of taxonomies through ad hoc network avoiding a pre-shared one.ADHOC-NOW 2012, Belgrade, Serbia Conclusions 19 / 20

Questions? Thank you!ADHOC-NOW 2012, Belgrade, Serbia Conclusions 20 / 20

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

by Unai Aguilera on Jul 16, 2012

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