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

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This lecture is part of a Web Information Systems course given at the Vrije Universiteit Brussel.

This lecture is part of a Web Information Systems course given at the Vrije Universiteit Brussel.

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  • 1. 2 December 2005 Web Information Systems Mobile Information Systems Prof. Beat Signer Department of Computer Science Vrije Universiteit Brussel http://www.beatsigner.com
  • 2. 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
  • 3. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 3 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 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 4 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 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 5 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 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 6 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 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 7 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 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 8 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 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 9 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 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 10 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, ...
  • 11. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 11 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
  • 12. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 12 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
  • 13. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 13 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
  • 14. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 14 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, ...
  • 15. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 15 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), ...
  • 16. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 16 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!
  • 17. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 17 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>
  • 18. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 18 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 <span class="geo">The office is located at <span class="latitude">50.820985</span>, <span class="longitude">4.392990</span> </span>
  • 19. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 19 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
  • 20. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 20 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, ...
  • 21. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 21 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
  • 22. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 22 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
  • 23. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 23 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
  • 24. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 24 Geolocation Example: Google Maps
  • 25. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 25 Geolocation Support When can I use..., http://caniuse.com/#search=geolocation
  • 26. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 26 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)
  • 27. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 27 Video: Microsoft's Vision of Future Retail
  • 28. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 28 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
  • 29. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 29 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
  • 30. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 30 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
  • 31. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 31 Paper as a Mobile Device
  • 32. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 32 Digital Pen and Paper  Anoto offers  camera technology  pattern license (virtual paper space of 60 million km2)  Pen manufacturers  Nokia  Maxell  Adapx  Livescribe
  • 33. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 33 Weaving the Mobile Paper Web  linking paper to digital information/services and vice-versa image video clip
  • 34. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 34 Use Case: EdFest Project Global Information Systems Group ETH Zurich
  • 35. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 35 EdFest Documents
  • 36. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 36 "Disappearing" User Interface
  • 37. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 37 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 Global Information Systems Group ETH Zurich
  • 38. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 38 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 Global Information Systems Group ETH Zurich
  • 39. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 39 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
  • 40. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 40 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
  • 41. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 41 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.
  • 42. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 42 Exercise 8  Google Maps and Geolocation API
  • 43. November 21, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 43 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
  • 44. 2 December 2005 Next Lecture Semantic Web