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Virtual Resources: Dynamically Sharing Mobile Platforms

With

Nitya Narasimhan

Venu Vasudevan

Motorola Labs, Schaumburg, IL

Karishma Babu, Ashish Bijlani, Ada Gavrilovska, Minsung Jang, Ankur Pai, Bala Seshasayee, Karsten Schwan

CERCS Center for Experimental Research in Computer Science

College of Computing

Georgia Institute of Technology, Atlanta, GA

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Motivation

• Modern mobile platforms create and consume content– Onboard camera, microphone, etc.– Variety of wireless technologies (bluetooth, GPRS, wifi, …)

• Enables rich interactions– “Live mobile youtube”: user-generated videos shared among

participants (e.g., soccer game, stage performance)– Citizen journalism (photos/images)– Ad hoc interest groups– Social networking

• Interactions inhibited by platform limitations– Limited on-board storage– Small form factors (display, keyboard)– Concerns with battery life– Worse with price-constrained devices like set-top boxes

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Opportunities

• Use virtualization technologies to create richer platforms via `illusion’ of `local’ devices, without need to change applications or operating systems:– “YouTube”/Social networking: storage devices – exploit

remote storage capabilities for content sharing, buffering, longer term storage

– Citizen journalism: cameras – use remote device for better content access

– Limitations: leverage other platforms in home environment: keyboard or display – use home PC keyboard or disk, TV display, home security system cameras, etc.

• Almost like `plug and play’ dynamic platform assembly

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Benefits of Virtualization

• Isolation of containers’ functionality & behavior from each other

• Information hiding – content of one VM remains inaccessible to others

• Use of existing OSs, interfaces• Separation of implementation/location of a functionality

from its use

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Issues

• Virtualization infrastructure must deal with/support:– Distribution/remote access– Access control/privacy issues– Support for different realizations, requiring standard APIs

• This project: concrete example: VStore:– Initial focus on storage devices– Distributed storage across mobile devices – VStore

architecture combines modern middleware with virtualization technologies

– Additional work addressing multimedia – VMedia

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VStore – Basic Design

guest domain storage/control domain

Application

Object-based FS client

Metadata Server

Data Server DHT

Hypervisor

Data on disk

Database

to peers

to peers

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Distributed VStore – Architecture Detail

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Searching & Sharing

• Metadata is used for indexing storage objects• Searching relies on this index to retrieve the

corresponding object(s)– Note: can imply remote operation and access

• Adhoc sharing– Each participant hosts their own objects– Metadata stored using a distributed hash table– Objects are exchanged between participants

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Opportunities (1/2)

• Flexible Access Controls– Metadata used to store access control related information– Variety of access controls can be implemented

• Role based

• Content based

• Context based

– Implementation can be entirely carried out in the backend, transparent to VMs

– Extensions based on dynamic trust - in progress

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Opportunities (2/2)

• Digital watermarking– Content ownership in a shared environment– Digital signing– Secure deletion: when owner requires all copies to be deleted– Audits: to keep track of file sharing dynamics

• Deferred fulfillment– Intermittent connectivity in mobile environments– Users intents stored for future actions when they cannot be

carried out immediately– Connectivity related dynamics are notified to OS via existing

mechanisms

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Ongoing & Future Work

• Improved, lightweight implementation now being evaluated experimentally – overheads, delays

• Trust extension being completed (Jiantao Kong)

• Port to cellphones using L4 and Xen platforms (Ashish, Minsung) in progress

• Considering/experimenting with other devices (set top boxes, gumstix)

• Deferred services not yet implemented

• Need for `more cycles’ for tasks like digital watermarking

• Dynamic trust models heavily dependent on social context – location, group consensus, … => more research is needed to make them usable

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Publications

• VStore - Efficiently Storing V(irtualized) State Across Mobile Devices, Balasubramanian Seshasayee (Georgia Tech), Nitya Narasimhan (Motorola Labs), Ashish Bijlani (Georgia Tech), Ankur Pai (Georgia Tech), Karsten Schwan (Georgia Tech), MobiVirt workshop, June 17, 2008, Breckenridge, Colorado.

• Netchannel: A VMM-level Mechanism for Continuous, Transparent Device Access During VM Migration, Sanjay Kumar and Karsten Schwan, ACM International Conference on Virtual Execution Environments (VEE), June 2008.

• VMedia: Enhanced Multimedia Services in Virtualized Systems, Himanshu Raj, Balasubramanian Seshasayee, Karsten Schwan, Fifteenth Annual Multimedia Computing and Networking (MMCN'08), January 30-31, 2008, San Jose, California.

• VStore II – under development