Pervasive computing involves interacting with embedded computers that are networked and aware of their surroundings. It allows accessing information and applications anywhere. Key goals are invisible technology, integrating virtual and physical worlds, and devices communicating without human intervention. Challenges include making computing invisible, scaling to many users and devices, ensuring availability anywhere, handling dynamic and mobile environments, integrating diverse hardware and software, and respecting user privacy. The Service Location Protocol allows devices to discover and interact with available services in a network.

1. Ali Bahu
03/24/2013
PERVASIVE
COMPUTING

2. INTRODUCTION
 An environment in which people interact with embedded (and
mostly invisible) computers (processors) and in which networked
devices are aware of their surroundings and peers and are able to
provide services or use services from peers effectively. It is the
ability to access information and software applications anytime
and anywhere. It is also Known as:
 Pervasive Computing
 Ubiquitous Computing
 Ambient Intelligence
 Wearable Computing
 Context Awareness

3. TODAY:
Cool toys…

4. OUR WORLD TODAY:
 Devices increasingly more
powerful.
 Devices are also becoming
smaller & cheaper.
 People interact daily with
hundreds of computing devices
(many of them mobile):
 Cars
 Desktops/Laptops
 Cell phones
 PDAs
 MP3 players
 Transportation passes, etc.

5. JUST NOW…
Too bad they
can’t talk to
each other…

6. TODAY…
Configuration?
Too much work…

7. GOALS OF PERVASIVE
COMPUTING
 As our lives are full of devices and gadgets with different
functionalities and abilities, it is becoming harder to keep track of
each one of them and use them efficiently and seamlessly. This is
where the pervasive computing come is into the picture with the
following goals:
 Invisible technology
 Integration of virtual and physical worlds
 Throughout desks, rooms, buildings, and life
 Take the data out of environment, leaving behind just an enhanced ability to act.
 Devices and services communicating with each other without any human
intervention or help.

8. PERVASIVE COMPUTING
APPLICATIONS
 Always running and available.
 Composed of collaborating parts spared over the network –
distributed components.
 Adapt to environments when the users/devices move –
reconfigure to use available services.
 Users are not aware of the computing embedded in the device –
transparent interaction.
 Information pursues the user rather than user pursues the
information.

9. SERVICE DISCOVERY
 Goal – allow devices to advertise, discover, configure, and
communicate with each other in a mobile network
 Example – when a device is moving between networks, it needs to
know what services are still available, will be available, and no longer
available. It also needs to know how to contact to these services.
Then, based on the resources, the device is able to perform its task and
for that Service Discovery Protocols are used.
 Service Discovery Protocols – protocol to facilitate association of
devices that have services to offer or that need services
 Enable interoperability
 Communication between devices
 Accommodate heterogeneity
 Devices can be of different kind
 Minimize administrative overhead
 Increase usability
 Simplified design time implementation

10. SERVICE LOCATION PROTOCOL
 A service discovery protocol for advertisement and discovery of network
services.
 Each service has a service type, which defines a collection of services
with a common nature.
 Each service has a name and a list of characteristics where each
characteristic is defined by a attribute-value pairing and Service with the
same service type have similar attributes but different values.
 For a device to connect to a service, a Service Access Point (SAP) is
needed which contains information about where and how to get the
service and secondly the structure of SAP is defined by URLs of
scheme service.

11. CONT.
 For the device to know if a service is what it needs, a Service
Advertisement is needed which contains information describing a
service including Service Type, the values of the attributes, and the
Service Access Point.
 Each device can be defined as an User Agent (UA) or a Service Agent
(SA) where User Agents are consumers of service and Service Agents
are providers of service.
 (Optionally) there is also a Directory Agent (DA) that maintains service
advertisements
 Many other service discovery protocols are available for example
Jini, Bluetooth, UPnP, Salutation, etc.
 The protocols are usually compose of the service clients (UA), service
providers (SA), and service directories (DA)

12. SERVICE DISCOVERY
PROTOCOLS

13. CHALLENGES
 Invisibility – disappearance of computing technology from users'
consciousness; embedding/combining computing infrastructure with
building infrastructure
 Scalability – scalability of users, devices, density of interactions in a
local area
 Availability – access to software applications and information anytime
and anywhere
 Dynamic – users and devices are mobile, services are provided by
collaborating distributed components
 Heterogeneity – variety of hardware, software platforms, network
protocols, service providers
 Integration with people – personal privacy, user intentions, access
control