Device capabilities
Adaptation
- Also considered multiserving
- Deliver content as per each user device's capabilities E.g if client device is.
- Old supporting only WML - show WML page with Wireless Bitmap (wbmp) images.
- Mordern XHTML MP-compliant - deliver an XHTML MP customised to the screen size
- on iMode (Japan) - Compact HTML (cHTML) version that's more forgiving than XHTML.
- Users get the best experience possible on their device.
What to adapt
- UI
- Menus, browser, etc
- Figures
- Colour, size
- Communication
- Packet sizes, chatty protocols?
- Operations
- Where all calculation/computations are done
Why adapt
- Web pages
- Browsers specific quirks - IE, Opera, firefox, Chrome, Lynx,etc
- Possibility to use service with heterogeous devices/applications
- Third party apps e.g. browsers, file manager, etc
- Own client apps can be run on different device types
When to adapt
- Adaptations can be taken into account either server or client side
- Server - more computing power thus fits better for adaptation
- Client can inform the server its capabilities
- Approaches of capability informing
- Client tells it all - CC/PP & UAProf
- Server fetches client device name & retrieves device capabilites from a database - Wurfl
- Your own custom built combining these two
Composite capabilities & preference profile (CC/PP)
- System for expressing device capabilities and preferences (delivery context)
- Defined by CC/PP WG by W2C
- Motive
- Differences in devices used to access services
- Provides the rules of how to construct vocabulary describing capabilities & preferences
- Does not define attributes & their values
- Based on RDF (resource description framework)
- XML
CC/PP ...
- CC/PP profile contains one or more features
- Component is a category of features e.g. software or hardware
- Each component contains one or more attributes e.g. screensize
- Each component may optionally specify a set of default values for attributes it contains
- Extensible
- Clients may refere to a standard profile & made additions / modifications to it.
- JSR 188 CC/PP processing
- Java API for processing CC/PP information
CC/PP exchange profiles
- Uses HTTP extension framework (RFC 2369)
- URI for CC/PP can be sent instead of huge profiles
- E.g. the device capabilities can be fetched from manufactures web page
- Only changes in profile can be transmitted to reduce network load
- E.g. sound turned off
- CC/PP is very verbose
- Compressed / Binary XML should be used on slow connections
- Work continued in device independence workgroup of W3C
- Defined CC/PP 2.0
- Until 01.07.2010 was developed at Ubiquitous Web Application Workgroup
User Agent Profile (UAProf)
- User agent → application interacting with the information source e.g. micro/minibrowser
- User agent profiles defines
- The capabilities of user agents
- Capabilities of the platform the user agent runs on
- Specific vocabulary for user agents based on CC/PP
UAProf ...
- 6 different components
- Hardware platform - e.g. Vendor, model, screen size, IO methods
- Sofware platform - e.g. OS, java support, audio & video encoder
- Network characteristics - e.g. Security support, bearer support (latency, reliability)
- Browser user agent - e.g. browser name, supported HTML & XML versions
- WAP charcteristics - e.g. supported WAP, WML versions, WML script libraries, WAP deck size
- Push characteristics - e.g. accepted type of content, maximum message size, content types of push message, maximum size of push message
UAProf ...
- UAProf decribes the transmission of profile from client to a server
UAProf ...
- Final profile arriving to server is a combination of characteristics on the transmission path
- Similar to CC/PP in UAProf - client states the default profile(hardware,sofware, browser capabilities)
- Network may add/overide networking characteristics in the profile during transmission
- On profile reaching a WAP proxy it may be updated with WAP characteristics
- With UAProf information - service can be adapted for the user device and network capabilities
- Better experience on the service use
- UAProf is also extensible
- Based on CC/PP which follow RDF model
UAPROF examples
Wireless Universal Resource FiLe (WURFL)
- Open source XML based repository for device capabilities
- aims to provide as much infomation about devices capabilities as possible
- information is provided by different people around the world
- Targeted for WAP page developers
- Can be used for other services as well
- requires computing power and memory as the
- API's for several languages exist
- Java, PHP, Perl, Python, .NET, XSLT, C++ tools
- Functions to find out necessary information
- Several tools provided tha use wurfl information to adapt content e.g. picture size
- Some commercial alternatives of device personalisation
WURFL examples
Resources
