Personal Activity Coordinator

1
Personal Activity Coordinator

• Shelley Zhuang
• Computer Science Division
• U.C. Berkeley
• Ericsson Workshop
• August 2000

2
PAC What is it?

• Service coordination layer
• Collects contextual user information such as
  current geo-location, next destination from
  services such as GPS service, calendar service,
  IM-Anywhere (real-time presence, location, and
  behavior information)
• Spatial data (location, traffic, device type,
  etc)
• Temporal data (calendar data)

3
Goals

• Uncoupling of providers and consumers
• Extensibility
• High availability and fault tolerance
• Scalability
• Security
• Privacy

4
PAC Applications

• Real-time information about PAC users, enabling
  targeted message delivery and other enhanced
  services
• Assists the Preference Registry for more powerful
  service customization

5
Contextual Information Categorization

• Categorizing contextual information information
  updating performance vs. finer grained access
  control)
• Hierarchical name space
• Sample hierarchical categorization tree

root
new appointments
traffic
location
calendar
fax
email
trip time
GPS
IP address
mailing address
location
person
6
Schema Definition

• XML namespace standard
• Referenced by a well-known URL
• Single schema definition file for each contextual
  information category
• Defines the properties of each field of a
  contextual information category
• Tags associated with each field are Name,
  Description, Type, Enforcement, Values

7
Hierarchical Domain-based PAC Organization

• Separate PAC is provided for each individual
  user ease of maintainability, privacy
• Individual PACs are organized in a hierarchical
  domain-based fashion
• Uniform contextual information presentation
  defined for each domain of PACs
• Child domains inherit the presentations defined
  by their parents
• Supports dynamic creation and deletion of a
  category, creation of additional fields for a
  category, and update of schema definition file
  URL at the domain level

8
Internal View of the PAC

• Hierarchical category namespace defined by the
  domain, and schema definition files
• Contextual information repository
• Subscriber Information
• Service consumers subscribe to contextual
  information categories
• Notified in response to the creation, deletion,
  update and expiration of contextual information

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Architecture of PAC
root
subscriber 1
subscriber 2
subscriber 5
subscriber server
subscriber 6
name Server
subscriber 7
subscriber server
subscriber 3
subscriber 4
subscriber server
name Server
name Server
Hierarchical Name Space
Subscribers Space
Subscribers Space
node server
node server
node server
node server
node server
node server
node server
node server
virtual node server
virtual node server
Contextual Information
Repository Light-weight semi-structured
distributed database
10
Security Privacy

• Public key infrastructure
• For each contextual information category, the
  user can specify an Access Control List (ACL)

11
Garbage Collector

• Contextual information stored as soft state
• Allow the service providers to specify the
  lasting period of a contextual information

12
Execution Environment

• Runs on a Ninja base (iSpace ? vSpace)
• Name Lookup Service (service-specific-id ? users
  unique-id ? personal information, i.e.,
  preference registry, public key, PAC
• Xset database XML based database and query model

13
Future Work

• Migrate to Ninja vSpace
• Implement the security model
• Support query-based notifications for finer
  grained control of the notification scheme
• Real-time changing data - GPS, IM-Anywhere
• Users current activity identify categorization
  and semantics