Mobile Information Systems - Lecture 08 - Web Information Systems (4011474FNR)

2 December 2005

Web Information Systems Mobile Information Systems

Prof. Beat Signer

Department of Computer Science

Vrije Universiteit Brussel

http://www.beatsigner.com

http://www.beatsigner.com/

Beat Signer - Department of Computer Science - [email protected]

2 November 22, 2013

Mobile Web

Web becomes accessible

from anywhere at anytime

notebooks, netbooks, mobile

phones, ...

New forms of connectivity

and information exchange

P2P networks

…

New requirements and

functionality

location-based services

context-awareness


3 November 22, 2013

2G Networks

Mainly designed for voice services conversations digitally compressed and encrypted

Best known 2G technology is GSM digital services also included SMS

Later the General Packet Radio Service (GPRS)

or 2.5G was added packet switching

pay for transfered data instead of connection time

transfer rates up to 114 kbit/s

WAP, email, MMS, WWW, ...


4 November 22, 2013

3G Networks

Set of standards for mobile telecommunication defined

by the International Telecommunication Union (ITU)

Higher transfer rates and better security minimum transfer rate of about 2 Mbit/s

authentification of the network

simultaneous use of speech and data transfer

mobile TV, video on demand, video conferencing, ...

Standards include Enhanced Data rates for GSM Evolution (EDGE)

- enhanced version of GSM with up to 1.9 Mbit/s

- note that since EDGE is slightly slower than other 3G standards, it is

sometimes also classified as 2.75G


5 November 22, 2013

3G Networks ...

Universal Mobile Telecommunications System (UMTS or 3GSM )

- requires new frequencies and antennas

- transfer rate of up to 14.4 Mbit/s

- used by other protocols

• e.g. High-Speed Downlink Packet Access (HSDPA)

Worldwide Interoperability for Microwave Access (WiMAX)

- based on IEEE 802.16 standard

- differs from Wi-Fi in how clients communicate with the wireless access point

(e.g. fixed assigned slot instead of competition for slots)

- covers up to 50 km distance and up to 1 Gbit/s (the larger the distance, the

smaller the transfer rate)

- alternative wireless technology for last mile connectivity

- should it be considered as a 4G network?


6 November 22, 2013

W3C Mobile Web Initiative (MWI)

The Mobile Web suffers from interoperability and

usability problems

Mobile Web Application Best Practices use cookies sparingly

do not execute unescaped or untrusted JSON data

optimise for application start-up time

inform the user about automatic network access

optimise network requests (e.g. compression or bundling)

keep DOM size resonable

...

Device Description Repository (DDR) Simple API standardised API for accessing device descriptors


7 November 22, 2013

Peer-to-Peer-Like Systems (P2P)

Many existing systems

work in a peer-to-peer-like

manner without a central

authority

e.g. the Simple Mail Transfer

Protocol (SMTP) where

Message Transfer Agents

(MTA) relay the messages to

each other

overlay networks

- peer-to-peer like behaviour on

top of other networks


8 November 22, 2013

Peer-to-Peer-Like Systems (P2P)

On the other hand, the Web has been de-

signed with a broadcasting-like architecture clients as consumers and servers as producers

what about Web 2.0?

In mobile information systems we often see

more P2P-like architectures automatic discovery of other peers

ad-hoc formation of new P2P networks (e.g. via Bluetooth)

- enables mesh networking in regions that are not covered by a wireless

network infrasturcture

- e.g. transmission of sensor or traffic data between moving cars

opportunistic information exchange

- spontanous information exchange based on the proximity of peers

One Laptop per Child


9 November 22, 2013

Peer-to-Peer-Like Systems (P2P) ...

In P2P networks each client provides some resources storage space, computing power, network bandwidth, ...

the capacity of the system grows with the number of peers

P2P systems are more robust since there is no single

point of failure

A disadvantage of P2P networks is the often increased

network traffic e.g. due to query flooding in older P2P systems

Not guaranteed that a query will be answered peers with the required data/functionality might not be available at

a given time


10 November 22, 2013

Context Awareness in Mobile Settings

Mobile settings users are often busy with multiple tasks/activities

limited functionality of mobile devices

- limited screen size

- non-visual output channels

- ...

A mobile information system should ensure that the user

gets the relevant information based on physical location

user preferences

time

environmental factors

- weather, noise pollution, other accompanying users, ...



Context Awareness

Often mobile systems focus only on location as context

such as in location-aware services

However, even if location is an important factor in mobile

applications, it is only one context dimension

Context is any information that can be used to character-

ize the situation of an entity. An entity is a person, place,

or object that is considered relevant to the interaction

between a user and an application, including the user and

applications themselves.

Anind K. Dey, 2000



Infrastructures for Context-Awareness

Instead of developing application-specific solutions, we

should design general models, mechanisms and

platforms to support the development and operation of

context-aware applications

In a general solution, all aspects of a web-based

information system might be context-aware content, structure and presentation



What is Needed?

Context model how is context defined for a specific application?

Context acquisition and representation from sensor data to context

how should the contextual state of an application be represented?

Mechanisms to support context-awareness how can we represent contextual variants of data?

what mechanisms can be used to deliver the right variants at the right time?

Methods for the design of context-aware applications



Support for Context-Awareness

Ubiquitous Computing Community focus is mainly on abstracting the sensor data layer

- from sensor data to logical context

e.g. Context Toolkit

- Dey and Abowd, Georgia Institute of Technology

Solutions from the Web Engineering community focus on adaptation and adaptivity of interfaces

- from data to context-dependant published information

generalised to cover many aspects of adaptation

- multi-channel, multi-lingual, location-based services, ...

There is a need for more general solutions to deal with

context-awareness on all levels in a uniform way sensors, data management, visualisation, ...



Location-Based Services (LBS)

Use contextual information about a person's or

object's position as part of a request

Different possibilities to get a client's position (manually entered by user)

Global Positioning System (GPS)

Wi-Fi signal strength

cell phone tower triangulation

RFID, Bluetooth and other tags

...

Potential applications include navigation services, tracking services (e.g. parcels),

location-based advertising, recommender systems (e.g. nearby restaurants), ...



Geotagging of Digital Resources

Add geographical metadata (latitude, longitude)

to different types of media websites

photographs

videos

RSS feeds

...

Metadata can be added manually or automatically e.g. recent digital cameras automatically geotag new pictures

Note that automatic geotagging may introduce some

privacy issues!



Geotagging of HTML Pages

GeoURL standard defines a metatag (ICBM) for adding

positional information to an HTML page tagged webpages can be added to the GeoURL directory

(http://geourl.org)

- currently a few million registered webpages

find nearby webpages (location-to-URL reverse directory)

location metadata can be used by other applications

- e.g. Google Maps mashup

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <title>WISE - Web and Information Systems Engineering</title> <meta name="ICBM" content="50.820985, 4.392990" /> ... </head> ... </html>



Geotagging of HTML Pages ...

Also the microformat approach (discussed next week)

can be used for HTML geotagging special Geo microformat

Many websites start to use Geo metadata Flickr, multimap.com, Wikipedia, ...

Some web browsers offer native access to any Geo

microformat metadata

The office is located at 50.820985, 4.392990 



Geo RSS

Geo RSS is used for location-aware RSS feeds two encodings: GeoRSS-Simple and GeoRSS GML

Other GeoRSS-Simple elements include <polygon>, <elev>, <featurename>, <featuretypetag>, ...

<?xml version="1.0" encoding="ISO-8859-1" ?> <rss version="2.0" xmlns:georss="http://www.georss.org/georss"> <channel> <title>W3Schools Home Page</title> <link>http://www.w3schools.com</link> <description>Free web building tutorials</description> <item> <title>RSS Tutorial</title> <link>http://www.w3schools.com/rss</link> <description>New RSS tutorial on W3Schools</description> <georss:point>46.5434 7.18747</georss:point> </item> ... </channel> ... </rss>

GeoRSS-Simple Example



Geography Markup Language (GML)

Markup language to define geographical features defined by the Open Geospatial Consortium (OGC)

deals not only with vector objects but also sensor data etc.

GML offers a rich set of primitives which can be used to

define specific application languages feature (representing a physical entity such as a building or river)

geometry

- note that a feature can have multiple geometries

coordinate reference system (CRS)

...

There exist various application-specific GML schemas e.g. CityGML for 3D urban city and landscape models

- viewers include LandXPlorer CityGML Viewer, CityGML4j, ...



Keyhole Markup Language (KML)

KML is an XML application for 2D and 3D annotation and

visualisation developed to be used with Google Earth (Keyhole Earth Viewer)

open standard for the visualisation of geographic information in geobrowsers managed by the OGC

note that a KML document can also contain GML data



Geolocation

Standard interface for accessing geographical

location information on the client device transparent access to different location information sources

- GPS, GSM cells, IP address, RFID, Wi-Fi connection etc.

Firefox uses the Google Location Service as default

lookup service send IP address and information about nearby wireless access

points to the Google Location Service and an approximate location will be computed

W3C C

andid

ate

Recom

mendation



Geolocation ...

JavaScript access to the Geolocation API access via the geolocation child object of the navigator object

we can also continuously monitor the client's position

function showPosition(position) { alert(position.coords.latitude + " " + position.coords.longitude); } function showError() { alert("Your current position cannot be computed!"); } navigator.geolocation.getCurrentPosition(showPosition, showError, {timeout:10000});

navigator.geolocation.watchPosition(showPosition);

W3C C

andid

ate

Recom

mendation



Geolocation Example: Google Maps



Geolocation Support

When can I use..., http://caniuse.com/#search=geolocation



Mobile Input Methods

Text-based navigation for screen-based systems WAP and other mobile browsers

Hands-free voice interfaces e.g. VoiceXML application with mobile phone as client device

Digital pen and paper-based user interfaces

Position (e.g. GPS) and orientation (digital compas) of a

device as input parameter

Use of camera image to drive the interaction e.g. augmented reality applications

Multiple input modalities can be used in combination to

achieve a specific task (multimodal user interfaces)



Video: Microsoft's Vision of Future Retail



Augmented Reality

Augmentation of the physical environment with digital

information and services mixed-reality

the physical environment becomes the user interface

Information can be visualised (overlaid) in different ways head-mounted displays (HMDs)

- see-through glasses with graphical overlay functionality

- registration with environment and tracking of glasses (6 degrees of freedom)

handheld displays

- make use of video see-through techniques

- today's camera phones offer the required hardware

fixed installations

- e.g. beamer projecting onto physical objects



Wikitude World Browser

The WIKITUDE World

browser presents

information about nearby

physical landmarks as

well as content added by

other users

Real-time augmentation of mobile phone camera view location-based augmented reality based on GPS, compass and

accelerometer

WIKITUDE.me authoring tool to add points of interest

WIKITUDE API for augmented reality applications



Ubiquitous Computing

Mark Weiser coined the term Ubiquitous

Computing while working at Xerox PARC

Digital information and services become

accessible through (mobile) physical objects

with embedded computing functionality mobile phones, RFID-tagged objects,

smart pens, …

Mark Weiser

The most profound technologies are those that disappear.

They weave themselves into the fabric of everyday life

until they are indistinguishable from it. ...

M. Weiser, The Computer for the 21st Century,

ACM Mobile Computing and Communications Review, July 1999



Paper as a Mobile Device



Digital Pen and Paper

Anoto offers

camera technology

pattern license

(virtual paper space

of 60 million km2)

Pen manufacturers

Nokia

Maxell

Adapx

Livescribe



Weaving the Mobile Paper Web

linking paper to digital information/services and vice-versa

image

video clip



Use Case: EdFest Project

Global Information Systems Group

ETH Zurich



EdFest Documents



"Disappearing" User Interface



Content-driven Cross-Media Publishing

XCM content publishing

XML data

of festival

venues

and events

iServer cross-media link server

import

publish

PDF

XML link

definition

data

iPublish publishing framework

Structure Style

XSL CSS

Information-centric approach


ETH Zurich



EdFest Architecture Overview

iPaper Client

XCM content publishing

platform

Metadata DB Appln DB

iServer/iPaper cross-media

link server

Link DB

Context

Engine

Context DB

Client

Controller

Active

Components

Text-to-Speech

Engine

ICR handwriting

recognition


ETH Zurich



Network Disconnection

What is the difference between failure and

disconnection? disconnection can be considered as planned failure

There may be various degrees of disconnection total disconnection due to user shut-down

disconnection due to loss of network connection

weak disconnection due to low bandwidth

How to deal with this kind of planned failure in mobile

distributed environments? one possible solution is to design new programming languages

dealing with potential network failures at the programming model

- e.g. AmbientTalk from the Software Languages Lab at the VUB



Power Issues in Mobile Systems

The powering of mobile

devices is still a problem we do not want to charge

them every few hours

The transmission of data

is often a "power killer"

Power can be saved by choosing an

appropriate data distribution and query processing transmitting data generally costs more than receiving

- broadcasting of information can save power

more computation on the server side if the client consumes a lot of power while processing data

...

Parasitic Power Shoes Project, MIT Media Lab



Conclusions

The future challenges in developing mobile information

systems are less on the hardware and protocol level. We

need to develop architectures, frameworks and

infrastructures dealing with distributed information and

service management in a flexible way and supporting

general forms of context-aware content delivery and

information sharing.



Exercise 8

Google Maps and Geolocation API



References

W3C Mobile Web Initiative http://www.w3.org/Mobile/

Mobile Web Applications Best Practices http://www.w3.org/TR/mwabp/

WIKITUDE World Browser http://www.wikitude.org

M.C. Norrie, B. Signer, M. Grossniklaus,

R. Belotti, C. Decurtins and N. Weibel, Context-Aware

Platform for Mobile Data Management, WINET, Vol. 13,

No. 6, Springer, December 2007 http://www.academia.edu/175422/Context-Aware_Platform_for_Mobile_Data_Management

2 December 2005

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Mobile Information Systems - Lecture 08 - Web Information Systems (4011474FNR)