Location Based Services Mobile Computing - CNT 5517 -5564 Dr. Sumi Helal Professor Computer & Information Science & Engineering Department University of Florida, Gainesville, FL 32611 helal@cise. ufl. edu
Reading Materials • • • Paolo Bellavista, Axel Küpper and Sumi Helal “Location Based Services – Back to the Future, ” the Standards, Tools and Emerging Technologies Department, IEEE Pervasive Computing Magazine, Sumi Helal, Editor, Volume 7, Number 2, April-June 2008 Roxin, A. , Dumez, C. , Wack, M. , and Gaber, J. 2008. Middleware models for location-based services: a survey. In Proceedings of the 2 nd international Workshop on Agent-Oriented Software Engineering Challenges For Ubiquitous and Pervasive Computing (Sorrento, Italy, July 06 - 06, 2008). AUPC '08. ACM, New York, NY, 35 -40. C. Lee, A. Helal and D. Nordstedt, "μJini Proxy Architecture for Impromptu Mobile Service Access, " Proceedings of the Workshop on Next Generation Service Platforms for Future Mobile Systems (SPMS 2006). In conjunction with the IEEE/IPSJ International Symposium on Applications and the Internet (SAINT), Phoenix, Arizona, January 2006. (pdf) 2
Overview • • • What is LBS? What is impromptu LBS? Examples Why did LBS not take off for the past 10 years? LBS Evolution Today’s LBS classification LBS Middleware Mobile Service Discovery Mobile Service Delivery Ongoing research 3
Location Based Services • A service whose rendering depends on the location of the service requester, service provider or both • Mobile, networked Applications – Input: geo references from Assisted GPS system – Client/server interaction – Output: Location relevant Information • Example: weather, tourist information, . .
Elements of LBS • • • Querying Advertisement Discovery Delivery Localization Management – No installs – Lease / Release • Location Privacy 5
Impromptu LBS
Impromptu LBS
Impromptu LBS
Why Difficult to Believe LBS did not take off?
Great Phones/ Great B/W 2. 5 -3 G Mobile Phones shown GPRS, EDVO, UMTS, … à 500 -800 K speed Who needs Hot Spots!
The Wi. MAX Possibility • Wireless & Mobile Broadband at 10 -30 miles range • The Fat Pipe problem. Mobile TV: no thank you!
Commoditization Pressure • The Skype Phenomena • Vo. IP as a cheaper mobile phone service • Signs of commoditization of the Telecom Industry? pressure on Telecom to explore new sources of revenues (= New Services).
Early LBS (1) § Content-Centric § § § Current LBSs are content-oriented and lack the logic necessary for user interactivity (no user models captured in the service) Content could be boring! And has limited impact as compared to interactions Content-centricity was not by choice, it was more of a constraint. Downloading content was what is available, and was challenging enough (e. g. WAP performance)
Early LBS (2) § Precision of the Localization subsystem § § § Cellular triangulation useful for some applications but inadequate for others. On-board GPS (e. g. , Assisted GPS) offers better accuracy, but does not work indoor. “Locate nearest Pizza place!” era of LBS § § Does not need accuracy Outdoor!
Early LBS (3) § Telecom-centric § § Localization data owned by Telco; location based information provided by telco; telco partners with other content providers (such as Verizon and Microsoft MSN – never took off, even with a massive publicity campaign). The centricity and encumbrance by telecom proved to be non-scalable and actually an impedance to the much-anticipated proliferation of the elegant LBS concept
The First Fix: From Content to Applications • Redefining LBS to be a framework not an application. – As an application, LBS, gets a location, passes it to an authoritative server (@telco), and then delivers back location relevant information to the target. This is one application – very limiting. – As a framework, LBS gets a location, passes it to servers owned or provided by third party participants (small, medium and large businesses, from a variety of industries), and then delivers back location relevant services (applications) to the target. This is unlimited number of applications. This is very flexible and much more exciting!
Requirement to the First Fix: Impromptu (flash) Delivery of Applications. • Middleware and intelligent markup languages should be developed to enable the development of compact size code that takes a few second to download and a couple of seconds to get interpreted and run on a mobile target equipped with the middleware engine. • Code not content: compact code gets interpreted to native computations utilizing native resources. • Net effect: – A few seconds instead of 10’s of seconds or minutes in delivery time – No installation, de-installation or management. – Applications appear & disappear.
The Second Fix: Enable Indoor Localization • • More investment in indoor localization technology. Standardizations Solve Privacy issues Bluetooth Example: Through the creation of a new “Legalized Snooping” profile – Snoop protocol – Pay customer to snoop – Access to customer profile – On the fly tailored applications • Technologies: Wi-Fi, Ultra wideband, or licensed frequencies.
The Third Fix Alter LBS Business Model • Telco to sell and profit from basic services only (data pipe, SMS pipe, . . and perhaps application pipe in the future). Telco no longer define LBS. • Empower third party to transact LBS directly with end users, using (and paying for) Telco basic services. This is B 2 C with B 2 B embedding. • Any business should be allowed to participate and offer LBS. A business should be able to develop “LBSlets” using simple LBS development kits. • Businesses can host their own LBSs either directly or through a web hosting service. • User to own and sell his/her LBS user profile.
LBS Evolution LBS features and supporting services 1996 FCC passed E-911 mandate Key technologies & activities Introduction of finder LBSs • Restaurants • Filling stations • ATMs • … First Child tracking services Google launches Google. Maps First locationbased Mobile gaming 2000 Deadline phase 1 of E-911 Integration of location data into Merging of social outdoor network and indoor services LBS Locationapplications based dating First Applicationcommercial oriented Proactive LBSs 2004 Emergence First commercial of RFID WLAN fingerprinting systems Introduction of 3 G networks First handset Supporting Java Location API 2008 2012 Mass market penetration of GPScapable mobiles Deadline phase 2 of E-911 Launch of New Galileo middleware features for Introspam duction of avoidance Android and privacy handset preservatio n First GPS works capable indoors i. Phone Emergence of common middleware for proactive, crossreferencing, and multitarget LBSs
LBS Evolution community orientation crossreferencing multi-target self-referencing single-target operator-centric positioning content-oriented reactive proactivity degree device-centric positioning application-oriented user centrality
Mobile Service Discovery • Impromptu service discovery and delivery – – Widespread use of diverse mobile devices Wireless hotspots and broadband coverage Location-based and other context-relevant services Most importantly: the Business Opportunity • Challenges of impromptu mobile services – – – User mobility Service portability across a wide range of mobile devices Relevance and suitability: avoiding the morass of the Web User Manageability Acceptable quality of service • An effective infrastructure is a key to realize this vision – Context-aware service discovery – Device-independent service delivery
Service Discovery Protocols • Service discovery is relatively new (late 1990 s). – IETF SLP, Sun Jini, UPn. P, and Salutation – Announce-listen model (Soft state model) • Ad-hoc Service Discovery – IBM DEAPSpace – Konark Service Gossip Protocol [LHD+03][HDV+03] • Wide-area Service Discovery – Wide-area extension to SLP (WASRV) – Berkeley Secure Service Discovery Service (SSDS)
Sever Selection Mechanisms • Selection of the best among replicated services – Availability, fault-tolerance, load-balance, and scalability • Server-side approach – HTTP redirect • Network-side approach – DNS round-robin, DNS LOC RR, DNS GL RR – IP Anycast, Cisco Distributed. Router – IETF RSer. Pool (Reliable Server Pooling) • Client-side approach – Smart. Client
Three-tier Mobile SDP (Choonhwa Lee et al) • Provide the most appropriate service to mobile users by exploiting any meaningful context information • Service classification by coverage Service class Coverage Primary selection criteria Example Proximity service Local area Proximity Nearby printer Domain service Domain Global service Global area Proximity and service Area guide service features Service quality, user Media service, memory, or storage service availability
Conceptual Model of the Three-tier Discovery Architecture Services Contexts Service Profile Device Description Other Context Information GSR Proximity Services Domain Services Global Services BA • Different selection criteria • Guided selection • User transparency • Scalability (Performance) Profile Server at home
Domain Discovery Sub-system • On-campus registry hierarchy example campus … CSE Bld Printer serivce MSL Bld … 4 th floor 3 rd floor … E 451 E 467 Printer?
Global Service Discovery … Domain hierarchy GSR BA GSR-capable registry BA-capable registry … Domain-3 GSR Domain-2 BA service BA BA Domain-1 Client
Service Delivery Technologies • Over the Air Downloads (OTA) – UI tailored to work on target device downloading the service • Universal Interactions – Device-Independent UI Languages • W 3 C XForms, INCITS/V 2 URC, XIML, UIML, CMU PUC – UI Remoting Approaches • UPn. P Remote UI, Jini Proxy Architecture • UI Authoring Styles (W 3 C DI) – Single Authoring • A single generic description (all-in-one approach) – Multiple Authoring • A UI for each type of client devices (Jini Service. UI project) – Flexible Authoring • Customized UIs for popular platforms and automatically generated interfaces for rare platforms
Java for Mobile Services • Java technologies for service portability and dynamic service discovery • J 2 ME – Java runtime environments optimized for mobile devices – Configurations: CLDC and CDC – Profiles: MIDP, FP, PP, and other optional packages • Jini – Dynamic service discovery framework on top of Java RMI – Jini Surrogate Architecture for resource-poor devices • Jini requires J 2 ME CDC/RMI Profile as the minimal runtime environment
Jini Proxy Architecture VTC-Based Service Delivery Jini Protocol Mobile Clients Jini Proxy (VTC Service Delivery) Service Providers Enhanced Jini Protocol Context-aware Jini Lookup Service Standard Jini Protocol Context-Aware Service Discovery
Jini Proxy Architecture • Jini Proxy – functions as a proxy to a Jini network w. r. t. service discovery – serves client devices as VTC servers for service delivery • Three delivery mode to bring discovered services to resource-constrained mobile devices – Client executable mode – VTC MIDlet emulation mode – VTC J 2 SE emulation mode • Capable of selecting the best adaptation depending on the service context
Thin-Client Approach to Service Delivery • VTC (Virtual Thin Client)-based adaptation – Three delivery modes: Client executable, MIDlet service emulation, J 2 SE service emulation • Built on top of Sun Jini and AT&T VNC • Smart-phone client (J 2 ME capable phone) • Four main components – – Jini Protocol Resident Client VTC Jini Proxy
Jini System Architecture 34
MIDlet Emulator (4) Display update KVM event (3) KVM event X 11 input event (2) Jini protocol Jini Proxy MIDlet runner (1) VNC server pool VNC desktop pool
VTC non-MIDlet Emulation Mode ZOOM
Performance Measurement
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