Context Aware Middleware

Grounded Theory for the survery. The theory emerges from the interrelatons of general categories

Traditional Middleware: Hide heterogeneity and distribution

in Pervasive Computing this heterogeneity and distribution is dealt with in Middleware, without hiding them.

Types of Context

• Environment (infra-structure, vs, or self-contained)
  
• Storage (ordering data based on context information, vs, centralized storage facilities for storing
  
• Reflection (reification and absorption) (aapplication, middlware, context info)
  
• Quality
• Adaption (transparent, profile, rules)
  
• Migrationi (adaptive middleware systems)
  
• Composition

Aura
1. task oriented
2. task manager: managing tasks
3. environment manager: managing services
4. context observer: managing context (i.e., the intent of the user)

CARMEN:
1. proxies
2. proxy will migrate with the user

• resource move with the agent
• copy the resources when they agent migrates
• using remote reference
• re-binding to new resources

Resources have profiles

• user profiles: preferences, security, ...
  
• device profiles: hardware and software devices, ...
  
• service component profiles: interface for services
  
• site profiles: a group of profiles belonging to a single location

CARISMA
Profile: metadata of the middleware
1. passive profiles: actions the middleware should take when specific context events occur
2. active profiles: relations between services used by the application and the policies to deliver them

reflection is used to alter the profile kept by the middleware

Cooltown
Devices, People, and things are identified by a URL

• context (where, when, who, what, how)
• relationships (Contains, isContainedIn, isNextTo, isCarriedBy)

CORTEX
based on sentient objects: sense and views the behavior of neighbouring objects, reasons about it, and manipulates physical objects accordingly. They dynamically discover each other and share context information

• Publisher - Subscriber: discovery
  
• Group Communication
• Context
• QoS management

configured at deployment time, configured at run-time using Java Reflection

Gaia
a meta-operating system

• location
• context: collected by context providers
  
• event

Entities:

• application
  
• services
  
• device
  
• person

MiddleWhere
uses location providers

• location service
• spatial database
• reasoning engine

The model for location consists of (Points, Lines, Polygons)

Quality of location information (resolution, freshness, confidence)

MobiPADS
Mobilet is the entity that provides a service

• slave: resides on the server
  
• master: resides on the mobile device

context of mobile devices: 1. processing power, 2. memory, 3. storage, 4. network device, 5. battery

applications have access to reflective interfaces for context, service configurations, and adaption strategies

SOCAM: ontologies to model context

Context Provider: external or internal context
Context Interpreter: external context provider
Context Database: instance of the ontology of context
Context Reasoner: to derive more contextual information
Service Location Service: the registry for locating services of Context Providers
Context-aware Mobile Service: services that a context provider registers with the Service Location Service

rules are used to associate services with context information

Types of Context
Geographical Context
Physical Context
Social Context
Organisational Context
User Context
Action Context
Time Context