Team 4 Pervasive Computing __________________________________ Abe El-Dewak Sheb Findik Kenneth Brancik Tom Lombardi

Introduction to Pervasive computing Pervasive computing is an emerging field that suggests the capability for users to perform daily computer activities on any device, at any time, and at any location Pervasive computing definition is broad to encompass a variety of technologies and applications

Introduction to Pervasive computing We see networked computers everywhere. For instance: At work we may interact daily with an Ethernet-connected desktop PC, a laptop with IEEE wireless connectivity stored in the briefcase, a Bluetooth-enabled PDA in the jacket, and a cell phone or pager with an integrated CDPD modem clipped on the belt At Home, we may find another desktop PC, a smart digital cable receiver box on top of the TV, and a 4 th –generation video game console next to the intelligent digital video recorder

Approach to utilize pervasive computing Leverage the existing variety of computing hardware that already surrounds us. We can enrich our lives by enabling applications and their session states to move seamlessly and automatically among these machines while providing service to the user regardless of location, time or platform The consolidation of user interactivity on these platforms into continuous, uninterrupted computing experience can get the public towards more sophisticated and useful mobile computing

System architecture to support this vision This architecture should provide a runtime system that allows a client application to move its state across heterogeneous client devices This capability can be implemented with known process migration or simple device “syncing” commonly used to synchronize PDA and a PC

Issues with common “syncing” approach 1. PDA or laptops may lack the hardware, software, or network bandwidth to handle data objects over the network coming from application server 2. Supporting data trans coding and dynamic user interactivity. (In many application the user is allowed to perform dynamic interactive operations which later is committed back to the application server. This scenario creates difficulties) Maintaining scalable service for large numbers of Heterogeneous clients

Application Session Handoff The answer to this challenge suggest the notion of a pervasive application that seamlessly and automatically follows a user over the network between heterogeneous client devices by utilizing a mechanism of “Application Session Handoff” This approach is suggested in a dissertation submitted by : “Thomas Phan”, the university of California. “Utilizing Application Session Handoff to support the Pervasive Computing vision in the Nascent Millennium”

Application Session Handoff (ASH) With Application Session Handoff (ASH), all interactivity appears to the user to be part of on single continuous application even when running on different machines Application is able to run by following its thread of execution and maintaining a stable set of data In the case of the pervasive application, its execution can be suspended even indefinitely as long as its session state can be saved and resumed at some point

ASH Session State Session state is a minimal set of application level data structures, files, and network connections required to encapsulate the current temporal and spatial location of the program during its execution Session state can be generated internally within the program from an application server or peer, or both Session state can follow the user from platform to platform while providing its services until it is explicitly ended by the user. At each device, the state is transcoded to fit the software, hardware, or bandwidth limitations of the platform

ASH development & architecture to support it With ASH users will be able to run their typical applications continuously across client devices which communicate with an application server acting as a data repository The clients may be some set of desktop workstations, laptops, display tablets, handheld pocket computers, or PDA. Each with its own bandwidth and computation characteristics Despite this degree of client heterogeneity, users will be able to seamlessly move an application’s sessions from one machine to another machine running some version of the same application

ASH development & architecture to support it This session transfer will use the network as a conduit allowing sessions to be suspended and restored from any network connected location A middleware proxy servers are placed between the clients and the application server to shield the user from any complexities and provides near instantaneous and uninterrupted computing convergence between platforms As an example: consider how client outfitted with the properties of ASH. If the user wants to move between different client devices, instead of having to Resynchronize information between devices the handoff capability of ASH seamlessly and automatically manages the transfer of information from one client to another via the proxy When user moves to another device, the program starts up in a similar, if not exact state as he had left it on the previous machine

ASH development & architecture to support it By moving from machine to machine along with the user, the pervasive application provides an assistive and comforting level of familiarity for the user in the face of extreme platform heterogeneity. The outcome is that a person can concentrate on work while moving between platforms because the user becomes accustomed to data availability rather than aware of its conspicuous absence among different machines

Other related work to ASH Other research work looked into mechanisms to move an application’s state across devices as: Process migration [Milojicic] File hoarding [Alonso] Network layer indirection [Perkins] Mobile agents [Rothermel] Handoff-like method [Bharat], [Richardson], [Banavar]

Pervasive application enabled with ASH moves its session state from one device to another. Session can be suspended when the session is not active and resumed when the user wishes to utilize it again

Application Session Handoff ASH The session appears to the user as one single continuous application even when running on different machines The application DO NOT move between devices ( that will require binary executable compatibility and homogeneous platforms) Instead, the session state in the form of encapsulated data is moved Each client may be running a different version of executable program so long as each properly suspend and/or resume the session state

illustrate ASH functionality A user working on a word processing document on a desktop PC in his office decides to go home. The use click a button the application encapsulates and suspends its session Transfers the session state to a local middleware proxy on the network The user reached home and decides to resume his work on a laptop connected to a dial-up modem User starts his word processing which in turn find a proxy to download the state and then reinstate the session to the same point the user had left it Unlike file transfer, the handoff capability allows programmers and service providers the flexibility to define a session state that contains all the necessary runtime data of the program in order to cleanly suspend, transfer, and resume the session