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

November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 2
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

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, ...

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

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?

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

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

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

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

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 Candidate Recommendation

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 Candidate Recommendation

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
Next Lecture
Semantic Web

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

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