unit 2 pervasive

UNIT – II    Pervasive Computing Devices

Requirements and Application:

Weiser’s vision for ubiquitous computing can be summarised in three core

requirements:

1. Computers need to be networked, distributed and transparently accessible.

2. Human–computer interaction needs to be hidden more.

3. Computers need to be context-aware in order to optimise their operation in their environment.

It is proposed that there are two additional core types of requirements for UbiCom systems:

4. Computers can operate autonomously, without human intervention, be self-governed, in contrast to pure human–computer interaction (point 2).

5. Computers can handle a multiplicity of dynamic actions and interactions, governed by intelligent decision-making and intelligent organisational interaction. This may entail some form of artificial intelligence in order to handle:

(a) incomplete and non-deterministic interactions;

(b) cooperation and competition between members of organisations;

(c) richer interaction through sharing of context, semantics and goals.

These environments are clustered into two groups: (a) human-centred, personal social and economic environments; and (b) physical environments of living things (ecologies) and inanimate physical phenomena.

These five UbiCom requirements and three types of environment (ICT, physical and human) are not mutually exclusive, they overlap and they will need to be combined.

Distributed ICT Systems:

ICT- Information and Communication Technology

CCI- Computer to Computer Interaction (Center-Center)

CPI- Computer to Physical Environment Interaction

HCI- Human to Computer Interaction

1.     Smart Devices

A.    Smart devices, e.g., personal computer, mobile phone, tend to be multi-purpose ICT devices,

B.     Operating as a single portal to access sets of popular multiple application services that may reside locally on the device or remotely on servers. There is a range of forms for smart devices.

C.     The main characteristics of smart devices are as follows: mobility, dynamic service discovery and intermittent resource access (concurrency, upgrading, etc.).

D.    Devices are often designed to be multi-functional because these ease access to, and simplify the interoperability of, multi-functions at run-time.

E.     However, the trade-off is in a decreased openness of the system to maintain (upgrade) hardware components and to support more dynamic flexible run-time interoperability.

       I.            Classroom

    II.            Smart Spaces

Smart spaces refer to built environments such as apartments, offices, museums, hospitals, schools, malls, university campuses, and outdoor areas that are enabled for co-operation of smart objects and systems, and for ubiquitous interaction with frequent and sporadic visitors.

Prime business scenarios include smart retail environments and public areas providing better service to customers and citizens, and home and office environments making living and working more comfortable and efficient.

 III.            Cooltown

 IV.            iRoom

2.     Smart Environments

Cook and Das (2007) refer to a smart environment as ‘one that is able to acquire and apply knowledge about the environment and its inhabitants in order to improve their experience in that environment’.

A.    A smart environment consists of a set of networked devices that have some connection to the physical world.

B.     Unlike smart devices, the devices that comprise a smart environment usually execute a single predefined task, e.g., motion or body heat sensors coupled to a door release and lock control. Embedded environment components can be designed to automatically respond to or to anticipate users’ interaction using iHCI (implicit human–computer interaction), e.g., a person walks towards a closed door, so the door automatically opens. Hence, smart environments support a bounded, local context of user interaction.

C.     Smart environment devices may also be fixed in the physical world at a location or mobile, e.g., air-born.

D.    A more evolutionary approach could impart minimal modifications to the environment through embedding devices such as surface mounted wireless sensor devices, cameras and microphones.

Smart Interaction

A.    In order for smart devices and smart environments to support the core properties of UbiCom, an additional type of design is needed to knit together their many individual activity interactions.

B.     Smart interaction is needed to promote a unified and continuous interaction model between UbiCom applications and their UbiCom infrastructure, physical world and human environments.

C.     In the smart interaction design model, system components dynamically organise and interact to achieve shared goals. This organisation may occur internally without any external influence, a self organising system, or this may be driven in part by external events.

D.    Components interact to achieve goals jointly because they are deliberately not designed to execute and complete sets of tasks to achieve goals all by themselves – they are not monolithic system components.

E.     There are several benefits to designs based upon sets of interacting components. A range of levels of interaction between UbiCom system components exists from basic to smart. 

F.      A distinction is made between (basic) interaction that uses fixed interaction protocols between two statically linked dependent parties versus (smart) interaction that uses richer interaction protocols between multiple dynamic independent parties or entities.

1.     Basic Interaction

Basic interaction typically involves two dependent parties: a sender and a receiver.

There are two main types of basic interaction, synchronous versus

asynchronous :

• Synchronous interaction: the interaction protocol consists of a flow of control of two messages, a request then a reply or response. The sender sends a request message to the specified receiver and waits for a reply to be received, e.g., a client component makes a request to a server component and gets a response.

• Asynchronous interaction: The interaction protocol consists of single messages that have no control of flow, a sender sends a message to a receiver without knowing necessarily if the receivers will receive the message or if there will be a subsequent reply, e.g., an error message is generated but it is not clear if the error will be handled leading to a response message.

2.     Smart Interaction

Asynchronous and synchronous interaction is considered part of the distributed system communication functions. In contrast, interactions that are coordinated, conventions based, semantics and linguistic-based and whose interactions are driven by dynamic organizations are considered to be smart interaction. Hence, smart interaction extends basic interactions as follows:

Coordinated interactions: different components act together to achieve a common goal using

explicit communication, e.g., a sender requests a receiver to handle a request to complete a subtask on the sender’s behalf and the interaction is synchronised to achieve this. There are different types of coordination such as orchestration (use of a central coordinator) versus choreography (use of a distributed coordinator).

• Policy and convention-based interaction: different components act together to achieve a common organisational goal but it is based upon agreed rules or contractual policies without necessarily requiring significant explicit communication protocols between them. This is based upon previously understood rules to define norms and abnormal behaviour and the use of commitments by members of organisations to adhere to policies or norms, e.g., movement of herds or flocks of animals are coordinated based upon rules such as keeping a minimum distance away from each other and moving with the centre of gravity, etc.

• Dynamic organisational interaction: organisations are systems which are arrangements of relationships (interactions) between individuals so that they produce a system with qualities not present at the level of individuals. Rich types of mediations can be used to engage others in organisations to complete tasks. There are many types of organisational interactional protocol such as auctions, brokers, contract-nets, subscriptions, etc.

• Semantic and linguistic interactions: communication, interoperability (shared definitions about the use of the communication) and coordination are enhanced if the components concerned

share common meanings of the terms exchanged and share a common language to express basic

structures for the semantic terms exchanged.