Location Based ServicesMobile Computing - CNT 5517-5564

Dr. Sumi HelalProfessor

Computer & Information Science & Engineering Department

University of Florida, Gainesville, FL 32611helal@cise.ufl.edu

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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 2nd 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)

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

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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 Privacy5

Impromptu LBS

Impromptu LBS

Impromptu LBS

Why Difficult to Believe LBS did not take off?

Great Phones/ Great B/W2.5-3G Mobile Phones shown

GPRS, EDVO, UMTS, …500-800 K speedWho needs Hot Spots!

The WiMAX Possibility

• Wireless & Mobile Broadband at 10-30 miles range• The Fat Pipe problem. Mobile TV: no thank you!

Commoditization Pressure

• The Skype Phenomena

• VoIP 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 FixAlter 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 B2C with B2B 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.

1996 2000 2004 2008 2012

Key technologies & activities

FCC passed E-911mandate

Deadline phase 1 of E-911

Deadline phase 2 of E-911

First handsetSupporting Java Location API

Mass market penetration of GPS-capable mobiles

Launch of Galileo

Intro-duction of Android handset

First commercial WLAN fingerprinting systems

Emergence of RFID

First GPS capable iPhone

LBS features and supporting services

Introductionof 3G networks

Introduction of finder LBSs•Restaurants•Filling stations•ATMs•…

Google launchesGoogleMaps

First Child tracking services

First location-based Mobile gaming

GPS worksindoors

Integration of location data into social network services

Location-based dating

First commercialProactive LBSs

Emergence of common middleware for proactive, cross-referencing, and multi-target LBSs

Application-oriented LBSs

New middleware features for spam avoidance and privacy preservation

Merging of outdoor and indoor LBS applications

LBS Evolution

user centrality

community orientation

operator-centricpositioning

self-referencingsingle-target

reactive

proactivity degreeproactive

device-centricpositioning

cross-referencingmulti-target

content-oriented application-oriented

LBS Evolution

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 1990s).– IETF SLP, Sun Jini, UPnP, 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 DistributedRouter– IETF RSerPool (Reliable Server Pooling)

• Client-side approach– SmartClient

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 Proximity and service features

Area guide service

Global service Global area Service quality, user memory, or availability

Media service, storage service

Conceptual Model of the Three-tier Discovery Architecture

ServiceProfileDevice

Description

Other ContextInformation

Global Services

Domain Services

Proximity Services

Profile Serverat home

BAGSR

ServicesContexts

•Different selection criteria•Guided selection•User transparency•Scalability (Performance)

Domain Discovery Sub-system

• On-campus registry hierarchy example

E 451

4th floor

E467

CSE Bld

3rd floor

campus

MSL Bld

…

…

…

Printer?

Printerserivce

Global Service Discovery

service BA

Client

GSR

…

Domain hierarchy

GSR-capable registry

BA-capable registryBA

GSR

…

BA

BA

Domain-1

Domain-2

Domain-3

Service Delivery Technologies

• Over the Air Downloads (OTA)– UI tailored to work on target device downloading the service

• Universal Interactions– Device-Independent UI Languages

• W3C XForms, INCITS/V2 URC, XIML, UIML, CMU PUC

– UI Remoting Approaches• UPnP Remote UI, Jini Proxy Architecture

• UI Authoring Styles (W3C DI)– Single Authoring

• A single generic description (all-in-one approach)

– Multiple Authoring• A UI for each type of client devices (Jini ServiceUI 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

• J2ME– 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 J2ME CDC/RMI Profile as the minimal runtime environment

Jini Proxy Architecture

MobileClients

Jini Proxy

(VTC Service Delivery)

Context-awareJini

Lookup Service

JiniProtocol

ServiceProviders

Enhanced Jini Protocol

Context-Aware Service Discovery

VTC-Based Service DeliveryS

tandard Jini Protocol

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 J2SE 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, J2SE service emulation

• Built on top of Sun Jini and AT&T VNC • Smart-phone client (J2ME capable phone)• Four main components

Jini Protocol – Resident Client– VTC Jini Proxy

Jini System Architecture

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Verifier

Adapter Jini Protocol

Jini Services

Dispatcher

Jini Proxy

Jini Lookup Services

Client Device

KVM

CLDC

MIDP

Application Space

ResidentClient

JAM

Jini Protocol

VNC Channel

VNCPNG Support

MIDlet EmulatorVTC Server

VTCClient

MIDlet Emulator

(2) Jini protocol

(1) VNC server pool

X11input event

VNC desktop pool

MIDletrunner

KVMevent

(4) Display update

(3) KVM event

(3) KVMevent

JiniProxy

ZOOM

VTC non-MIDlet Emulation Mode

Performance Measurement

Comparison of Local Execution Startup and VTC Startup

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50

100

150

200

250

300

iCoffee~35kB Jar

File

Shopping~23kB Jar

File

PhoneClient~24kB Jar

File

MapIt ~34kBJar File

MIDlet Name & Size

Se

co

nd

s

Local Execution

VTC