Peer to Peer Overlay Network for Sensor net Eng. Husam Alzaq Computer Engineering Department Islamic University of Gaza 1

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Agenda ConclusionDesign & EvaluationBackgroundIntroduction  Introduction  Background on  Wireless Sensor Network  Peer to Peer Systems  Concept  Implementation  Results  Conclusion 2/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq What are Wireless Sensor Nodes? ConclusionDesign & EvaluationBackgroundIntroduction  They are small electronic components capable of sensing many types of information from the environment.  They are equipped with a certain amount of computational power, communication, storage and often actuation resources. 3/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq What is WSN? ConclusionDesign & EvaluationBackgroundIntroduction  It is a network that has multiple nodes connected to each other wirelessly  Sensor Network is distributed and is not structured. 4/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Constraints/Challanges ConclusionDesign & EvaluationBackgroundIntroduction  Hardware  Power Consumption  Software  Issues to be addresses:  Lifetime maximization  Robustness and fault tolerance  Self-configuration  Algorithms  Design of energy-aware algorithms 5/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Motivation ConclusionDesign & EvaluationBackgroundIntroduction  Motivation  Home/Office Observing –How can a user connect to Wireless Sensor Network over Internet? –How can a user retrieve the sensor data? What is the temperature at lab146?? 6/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Motivation ConclusionDesign & EvaluationBackgroundIntroduction  Solution  Peer to Peer Systems provide an overlay network that is able to connect a user to a Wireless Sensor Network.  Declarative Query would serve as a way to express user’s requests. 7/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq A Middleware for Sensor Networks ConclusionDesign & EvaluationBackgroundIntroduction  A middleware for sensor networks supports the development, maintenance, deployment, and execution of sensing-based applications.  Building a Peer to Peer application on existing WSN is important.  The complexity of accessing different sensor nodes must be hidden.  Many services can be offered. – Discovering Sensor gateway – Obtaining sensor data  Distributed Wireless Sensor Networks (WSNs) can be observed. 8/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Peer to Peer Systems ConclusionDesign & EvaluationBackgroundIntroduction  A Peer to Peer system is defined as a class of systems and applications that employs distributed resources to perform a critical function in a decentralized manner.  The resources encompass computing power, data, network bandwidth...etc.  The critical function can be distributed computing, data/content sharing, communication and collaboration, or platform services. 9/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Peer to Peer Characteristics ConclusionDesign & EvaluationBackgroundIntroduction  Symmetry  Decentralization  Scalability  Fault tolerant  Self-Organization  Resources Sharing  Fast Resource Location to determine where to find the resource 10/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Peer to Peer Classification ConclusionDesign & EvaluationBackgroundIntroduction P2PUnstructured Super P2P Model Hybrid Fully decentalized Structured 11/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Peer to Peer Classification ConclusionDesign & EvaluationBackgroundIntroduction 12/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Why Jxta? ConclusionDesign & EvaluationBackgroundIntroduction  Jxta is a generic overlay network system.  It consists of a set of protocols that are language, platform and network independent.  Java based and C implementation  It connects devices on the network ranging from embedded system and cellular phones to PCs and servers. 13/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Application Overview ConclusionDesign & EvaluationBackgroundIntroduction 14/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Requirements ConclusionDesign & EvaluationBackgroundIntroduction  Application Requirements  Detect sensor gateways.  Express user‘s requests in a SQL language.  Filter sensor data according to user request.  Technical Requirements.  Scalability.  Interoperability. 15/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Conceptual Design - Architecture ConclusionDesign & EvaluationBackgroundIntroduction  Jxta Layer  Governs the connection between a gateway and user agents, and the overlay network.  Ensures the interoperability between a gateway and user agents. 16/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Conceptual Design - Architecture ConclusionDesign & EvaluationBackgroundIntroduction  Sensor Gateway Layers  Sensor Network Interface Layer. – Extracts data from a sensor UDP packet and hands it to the Sensor Application layer.  Sensor Application Layer. –Manages all interactions between users and sensor nodes such as filtering data.  User Agents Layers  User Interface Layer.  WSN Application Layer. –Handles all user queries. –Handles all messages. 17/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Conceptual Design ConclusionDesign & EvaluationBackgroundIntroduction Block Diagram User AgentSensor Gateway 18/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Publishing & Discovery Process ConclusionDesign & EvaluationBackgroundIntroduction 1. Sensor Gateway publishes Advertisements on sensor nodes. 2. Jxta Overlay Network indexes these advertisements. 3. User Agent searches for advertisements.  Each advertisement includes  Set of properties that describe the sensor gateway –Name –Location –Description  Set of attributes that are provided by each sensor node. –types of data that the specified sensor can measure i.e. temperature, light... etc. and their units. 19/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Message Handler ConclusionDesign & EvaluationBackgroundIntroduction  A gateway and a user agents exchange a Jxta XML messages over a Jxta pipe.  Messages are used to  Create a new filter  Remove a filter  Send the filter results 20/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Distributed Query Process ConclusionDesign & EvaluationBackgroundIntroduction  Requests are expressed in a SQL-like query language to retrieve sensor data.  User query consists of  SELECT clause: specifies attributes, in which user is interested in.  FROM clause: specifies the name of the sensor gateway.  WHERE clause: filters sensor records by a predicate.  DURATION clause: is the period of time, which specifies how long the query should be run before terminated and removed from the filter list. (Select * From lab146.ibr.cs.tu-bs.de where Temperature < 20 duration = 600) 21/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Distributed Query Process ConclusionDesign & EvaluationBackgroundIntroduction  Query is distributively processed as follows: 1. The gateway name is extracted from the user query (specified in FROM) in order to establish a connection with the gateway. 2. The WHERE clause is encapsulated in a Query XML-based message. 3. The Query message is sent out to the gateway. 4. After that, the received results are displayed according to SELECT clause. 5. Query is terminated either by user or by gateway. 22/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Filter Process ConclusionDesign & EvaluationBackgroundIntroduction  Filter process is a way to suppress sensor tuples from randomly propagation and hand them in graceful manner to all interested users  Sensor tuples are a discrete raw of data  generated at discrete time  not stored in a data warehouse.  Filter is created by a user query.  Filter is activated for each received tuples.  Filter is only deleted in two cases  by user -> explicitly or implicitly  time is up 23/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Filter Process ConclusionDesign & EvaluationBackgroundIntroduction  Filter mechanism is based on attributes, which are described by key-value-operator.  Key indicates the semantics of the attribute  Operator describes how attributes will match when two attributes are compared (, =,... etc.)..  Typical attributes values – Sensor reading includes, temperature, voltage, light....etc. – Meta-data encompasses general information about a sensor node e.g. sensor ID. – Internal state is any information that is not related to sensor reading, such as timestamps. 24/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Implementation ConclusionDesign & EvaluationBackgroundIntroduction  A Sensor Gateway implements the basic functionality of the sensor agent.  The implementation is based on Jxta-C (version 2.5).  A User Agent prototype implements a user interface for JMSN, which is able to discover advertisements access any available sensor network.  The implementation is based on Jxta J2SE platform.  A prototype for a sensor application over a Peer to Peer System is named as Jxta Middleware for Sensor Network (JMSN). It consists of: 25/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq User Agent, GUI ConclusionDesign & EvaluationBackgroundIntroduction 26/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Evaluation ConclusionDesign & EvaluationBackgroundIntroduction Test-bed Equipments  Tests ware performed at the Workstation pool of IBR, where twelve machines of identical hardware are used.  They are equipped with –Intel Pentium(r) D CPU 3.2GHz –2.00 GB of RAM –Fast Ethernet card.  Half of them run Windows XP and the other run Debian GNU/Linux distribution. 27/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Evaluation - Memory Performance ConclusionDesign & EvaluationBackgroundIntroduction  This memory footprint is mainly due to the Apache Runtime (APR), which is embedded in the Jxta-C implementation.  It is observed that 8 threads are created (using DDD - Data Display Debugger) Summary of memory consumption tests. 28/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Evaluation – Filter Overhead ConclusionDesign & EvaluationBackgroundIntroduction  Constant message size  Time is linear in n with a slope of ms/filter operation.  The overhead of each filter process includes the time to  process the filter  searching for user PipeAdvertisement  establishing a connection  sending the message. – TCP transport is using blocking I/O. 29/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Conclusion Design & EvaluationBackgroundIntroduction  Peer to Peer Systems provide a decentralized approach that does not require any costly infrastructure.  Jxta was selected among other systems since it is a generic overlay network that connects devices on the network.  The design of “Peer to Peer overlay network for sensornets” combines a peer service discovery with a distributed query processing.  JMSN design doesn‘t come without cost. Results showed that the current implementation of Jxta-C consumes memory, which is not efficient for embedded system with limited memory. 30/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq Future Work ConclusionDesign & EvaluationBackgroundIntroduction  It is essential to extend the current version of Jxta-C implementation to cope with the limited memory devices.  It is necessary to enhance the user agent with  complex query  searching by partial names and attributes such as Location.  Aggregate function such as Average, Max, Count...etc. 31/31

Peer to Peer Overlay Netzwerk für Sensorennetze Husam Alzaq ConclusionDesign & EvaluationBackgroundIntroduction  شكراًَ لاستماعكم  Thanks for your attention 32/31