Screen Spot: Multidimensional Resource Discovery for Distributed Applications in Smart Spaces

7/31/2019 Screen Spot: Multidimensional Resource Discovery for Distributed Applications in Smart Spaces

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Presented by

Mr. Abhishek KumarMr. Piyush NayakStudent IES IPS Academy


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ABSTRACTThe big challenge related to the contemporary research onubiquitous and pervasive computing is that of seamlessintegration.

In this paper, we present middleware-level resourcemanagement service for situated displays in public smartspaces, acting as a scheduler and an arbiter for mobileclients. We have implemented the discovery service and subjectedit for alpha testing in an indoor setting. We report a proof-of-concept implementation of the Screen Spot system and we demonstrate an approach of visualizing the discovery results to the user.


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INTRODUCTION A typical usage scenario in this research field involvesa mobile user with a smart phone, PDA or other similarnetworked terminal, utilizing services from theambient surroundings.

STEPS1) the user issues a discovery request including certain

discrete keywords to the service repository.2) which in turn performs static matchmaking to return

a set of matching service descriptions from thedirectory.


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3) the mobile client utilizes this proxy to control and exchangedata with the remote service.

In the case of distributed and non-directory-based discovery protocol, two operational modes are possible.1) The pull-based model.2) The push-based model.


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The Pull based model & The Push

based modelIn pull based model theclient issues servicerequests as multicastmessages to the networkin order to discoversuitable servicecandidates.

In the push-basedmodel, the serviceimplementations publishadvertisements of theirpresence to the network,and clients can tap tothis traffic to performdiscovery.


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Usage Scenario

These hotspots in conjunction with the personal mobiledevices allow the deployment of distributedapplication structures that realize multimodal userinterfaces towards the users.


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In addition to the aforementioned connectivity, the mobileterminals also engage ad-hoc communications with theambient RM instances through Bluetooth.

Through this short-range ad-hoc connectivity, we want tophysically enforce the aspect of spatial proximity to thecomputation.

The Bluetooth coverage area forms an ad-hoc connectivity

hot-spot around the situated display, and we utilize thiscoverage area as a virtual watchdog for monitoring theproximity between user and the display.


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Through this functionality, the leasing for thedisplay can be monitored in a way that user canterminate the leasing session merely by walkingaway from the display thus we inhibit an implicit

interaction session termination through theBluetooth watchdog beacons.


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High-level architecture of Screen Spot.


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Component structure on a situated display


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IEEE 802.11b WLAN802.11 is a set of IEEE standards that govern wirelessnetworking transmission methods.

802.11b has a maximum raw data rate of 11 Mbit/s anduses the CSMA/CA media access method defined inthe original standard.Due to the CSMA/CA protocol overhead, in practice

the maximum 802.11b throughput that an applicationcan achieve is about 5.9 Mbit/s using TCP and 7.1Mbit/s using UDP.


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IEEE802.3 EthernetIEEE 802.3 is a working group and a collectionof IEEE standards produced by the working groupdefining the physical layer and data link layer's mediaaccess control (MAC) of wired Ethernet.This is generally a local area network technology withsome wide area network applications.

Physical connections are made between nodes and/orinfrastructure devices (hubs, switches, routers) by various types of copper or fiber cable.


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Resource ManagerThis instance resides within each situated display, andis responsible for the allocation and scheduling of theresource instance, as well as the execution of serviceinstances residing on the resource.This design reflects the tight coupling of the resource with the associated services, which is essential in thecase of stateful distributed applications.

During the execution, it may be necessary to inject theapplication-related data from the client side to therespective ambient resource to reflect the state of thedistributed application.


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The Resource Manager component forms the core of the RM instance and coordinates the othercomponents.It realizes the discovery interface towards the mobileclients, and controls the execution of the discovery

procedure.


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Policy ManagerPolicy Manager acts as a container and controller forthe usage policies set for this resource.

A single usage policy is an aggregation of resourceutilization rules for a single user group.These include an access control list with usernames of the group, the renewal policies allowed for the group,

as well as the role that the group has in the smartspace, i.e. employee vs. guest.


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Fuego pub/sub clientFuego pub/sub client realizes the networking interfacetowards the publish/subscribe routing system.

The subscription semantics utilized in the discovery service are hybrid in nature.First, the routing system realizes a separatesubscription channel for the discovery traffic.

Secondly, the RM instance on each ambient resourcesubscribes only to the messages targeted to this groupof instances.


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This decoupled routing scheme allows a flexiblemaintenance of the smart space, which isnt difficultand sometimes impossible to perform through acomplete shutdown and restart.

A discovery request sent to the network is only received by running resource managers that have anactive and subscription, and thus are ready forresource utilization and service deployment.


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Lease QueueLease Queue maintains the queuing of the leases setfor the resource. Instance by mobile clients.The basic queuing scheme is FIFO.It should be noted that pre-emptive scheduling of users in this setting is highly counterproductive,especially when considering stateful applications.


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Service ProxyService Proxy acts as a singleton interface towards thecore, and allows the execution of the service binariesresiding within this resource object.The service binaries are tightly coupled with theresource instance and the users issue utilizationrequests to the resource by setting leases to theassociated lease queue.Each lease must be associatively connected to adeployable service binary.


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BT ServerBT Server implements the physical Bluetoothconnectivity around the ambient hotspot.This spatial connectivity has two distinct roles in oursystem.First, users residing within the Bluetooth coverage areaof a single hotspot can perform discovery requests to

the rest of the system through the local hotspot.Secondly, during the resource deployment, theBluetooth coverage area acts as a virtual spatial watchdog.


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Functionality

The main functionality of the system is to performdiscovery requests within a physical smart spacedomain and return multidimensional resourceinformation back to the user.The attachment points for end users in the system areBluetooth coverage areas around the ambient hotspotsthat provide resources and deployable services.


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Virtual spatial ranges from the seed instance


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As the user is residing within an ambient hotspot when the

discovery is initiated, the RM instance managing thishotspot becomes the seed for the discovery request.

From this seed, other RM instances within the smart spacedomain appear on different virtual spatial ranges, denoting

relative physical distances between the hotspots.


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Range zero consists of the local hotspot, and the successiveranges are dependent on the location model configured tothe system.

Range 1 can for example denote hotspots within the same

floor as the seed instance. Range 2 denotes instances within the next floor up. Outer ranges denote other areas within the smart space

physical domain.


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THANK YOU

Documents

Screen Spot: Multidimensional Resource Discovery for Distributed Applications in Smart Spaces