Reference:

1
Building Personal Context-Aware Systems -
Realizing ACAS infrastructure for personal
useWei Li Computer and Systems Sciences
DepartmentRoyal Institute of Technology
Real World Implementation
Introduction The ACAS project has developed a
conceptual middleware solution to provide
adaptive applications a simple access of
distributed context information. This solution is
built upon a number of components (named context
entities), which interact with each other to form
a Context Network to ensure a desirable delivery
of required information. This poster addresses
the issues toward realizing the proposed solution
in the circumstance of real life, specifically
about the issues of how to acquire context
information from users with respect to their
economical affordability and personal
privacy protection.

• Bluetooth Detector a convenient way of providing
  users location (and other) context.

• Short range radio (10m, adjustable!)
• Commonly available
• Less power consumption
• Give rich Information (more than just MAC address)

Accessible over the net e.g., use Telnet gt
Telnet ServerHost 8989 gt Subscribe Appeared gt
Subscribe Disappeared gt Subscribe Present gt gt
Quit (or Exit)

• Person Centric System View
• The Personal Server works as a central and
  persistent online representative of a user
  (figure 1)
• Resides on users home network (e.g., their home
  desktop PCs)
• Holds a central storage of users context
  information as well as other entities like
  context manager, context server etc.
• Acts as a remote mediator to assist users local
  communication and interaction taking
  consideration of their situations

lt?xml version"1.0" encoding"UTF-8"
?gt ltBTDevList category"present" amount"2"
detector"070f546796103" location"FuseLab
Pentagon"gt ltBTDevice address" 08001719c4b6"
type"Computer Handheld PC/PDA
service"Networking ,Object Transfer , Audio"
timestamp"11147V1607531 Fri Apr 29
014007 CET 2005" presentFrom"11147V1607531
Fri Apr 29 014007 CEST
2005"gtskypeliweilt/BTDevicegt ltBTDevice
address"000ad91452ee" type"Phone Smart phone"
service"Limited Discovery , Object
Transfer" timestamp"11147V1607481 Fri Apr 29
014007 CEST 2005" presentFrom"11147V160
7481 Fri Apr 29 014007 CEST
2005"gtmsnliwei_at_hotmail.comlt/BTDevicegt lt/BTDevList
gt
Figure 1. Central Personal Server three types of
context reports arrive from difference sources
continuous context updates from users familiar
places (e.g., home and office) irregular context
reports from users mobile devices when their
connections are intermittent and occasional
context exchange with the unfamiliar people and
environment in the users vicinity. Each place
and user may have a central context entity which
aggregates the associated information and manages
the access to it.

• Pseudonym Based Context Sharing
• The Anonymizer Proxy Server helps to provide user
  privacy protection by hiding users real identity
  with pseudonyms when
• communicating with untrustworthy parties (Figure
  )
• A pseudonym is an abstract (literally neutral)
  URI pointing to the users Anonymizer Proxy
• The Anonymizer Proxy Server is hosted by a user
  trusted third party to provide a mapping service
  between users abstract URI and the real
  communication identity.
• A number of pseudonym is agreed between users
  mobile system and the Anonymizer Proxy before
  hand
• These agreed pseudonyms will be noticed (via
  detection) by the local parties in the proximity.
  And the unfamiliar parties can use this detected
  pseudonym to send context requests or reports to
  the Anonymizer Proxy Server
• The Anonymizer Proxy Server will decide where and
  how to forward the context requests to the users
  context system based on knowledge of pseudonym
  mapping
• The Personal Context System will also decide
  whether to reply the request directly or go
  through the Anonymizer Proxy Server again

The server produces four types of events for
subscribers (context consumers) appearing,
appeared, disappeared and present. Each event
consists of a list of devices, the device name in
the example is set with users IM account

• IM Networks an alternative realization of
  pseudonym based context sharing

Personal Server with IM URI yahooabc_at_yahoo.com
IM Networks SIP, MSN, Yahoo, Skype
Local Infra-structure Service
Anonymizer Proxy Server
Name device with users Personal Server IM URI,
like yahooabc_at_yahoo.com
Bluetooth Detector
Dynamic association withBluetooth discovery
Figure 2. A Dynamically Formed Context Network
with Anonymity Support the personal server
controls the access of personal data according to
the users permission while the Anonymous Proxy
Server helps to decrease user tractability caused
by context sharing. With these two components,
the user is provided better protection for their
personal data.

• Demo Application adding context (location)
  awareness to legacy software services (TeamSpace
  1)

Auto Mode
Manual Mode

• Reference
• 1 TeamSpace paper

Conclusion By making more use of the available
hardware and software technologies, we can lower
the entry of context aware systems by encouraging
and providing support for normal users to
actively participate in constructing individual
context systems which we hope will have big
impact for putting context system into real
life use.