Discovery and Search
T-106.5840 Internet of Things Matias Piispanen [email protected]
October 6, 2011 Contents
• Introduction • Search in Internet • Search in Internet of Things • EPCglobal • Conclusion
Introduction
Search problems in IoT: • High amount of devices • Heterogenous devices – RFID tags, sensors, actuators, ... • Distributed databases • Dynamic data • What are we searching?
Search in Internet – Case Google
• Googlebot crawls documents on the web – Static content – Only a part of the whole web!
• Found pages indexed in BigTable – Sparse, distributed and multidimensional sorted map
• PageRank
“Google” for IoT?
• Crawling is not possible – No links – Data is real-time
• Different ways of updating sensor data – Push – Pull – Sensor Ranking
Sensor Ranking
• Sensors data is sorted based on a prediction model – For example data is often cyclic or recent data is probably still accurate
• Pull data one by one until enough desirable results are found
• Better scalability than push and pull approaches – Still limited scalability
Tracking Physical Objects
• Objects need to be uniquely identified – RFID, barcodes, ...
• Objects are typically not connected to a network
• Local data – Global Search
• Distributed data
Supply Chain Management
EPCglobal Network
• Standard for sharing EPC (Electronic Product Code) related data • EPC Information Services (EPCIS) – Stores EPC Events – Offers a query interface • EPC Discovery Services (EPCDS) • Object Name Service (ONS)
EPCglobal Network Architecture
EPC Information Services
• Repository for EPC read events • Query interface
• EPC Read Event - What, Where, When, Why? – EPC Number – Event Time – Action – Location – Other data
Discovery Service Architecture
• There are many possibilities for the architecture of a Discovery Service – Directory of Resources – Notification of Resources – Notification of Clients – Query Propagation – Aggregating Discovery Service – P2P
• Different approaches to security
EPC Discovery Service
• EPCIS's inform EPCDS about the first read event for each EPC – EPC Number – URL of the EPCIS – Certificate of the company – Visibility – Timestamp • Supports ad hoc queries and registering for standing queries • Handles security concerns
Object Name Service (ONS)
• DNS-based service that resolves resources to an EPC
EPC Numbering Scheme:
• Granularity at product type level – resolves the EPC number to only one EPCIS
Search Problems
• Scalability is again a problem. There can't be just one discovery service • Not all EPCIS's are necessarily part of the same EPCDS network • It is unclear how to locate the correct discovery service given an EPC – Object Name Services – P2P • Searching only possible using the EPC number
Conclusion
• Scalability is an issue in Internet of Things
• Data is often distributed and not public
• No “One size fits all” solutions
• Global vs Local
Thank You!
References
Ostermaier, B. & Römer, K. & Mattern, F. & Fahrmair, M & Kellerer, W. A Real- Time Search Engine for the Web of Things. Available: http://www.vs.inf.ethz.ch/publ/papers/dyser.pdf
Lorentz, M. & Müller, J. & Schapranow, M. & Zeier, A. & Plattner, H. Discovery Services in the EPC Network. Available: http://www.intechopen.com/source/pdfs/18103/InTech-Discovery_services_in_the_epc_network.pdf
Beier, S. & Grandison, T. & Kailing, K. & Rantzau, R. Discovery Services— Enabling RFID Traceability in EPCglobal Networks. Available: http://www.cse.iitb.ac.in/comad/2006/proceedings/214.pdf
References
Evdokimov, S. & Fabian, B. & Kunz, S. & Schoenemann, N. Comparison of Discovery Services for the Internet of Things. Available: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5504696&isnumber=5504621
Guinard, D. & Karnouskos, S. & Trifa, V. & Dober, B. & Spiess, P. & Savio, D. Interacting with the SOA-based Internet of Things: Discovery, Query, Selection, and On-Demand Provisioning of Web Services. Available: http://vladtrifa.com/research/files/Guinard10tsc.pdf