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OverviewOverview ofof MoCAMoCA::Mobile Mobile CollaborationCollaboration ArchitectureArchitecture

Laboratory for Advanced Collaboration

PUC-Rio, Brazil

May 2006

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AgendaAgenda

• Research Goals

• The big picture

• Main Components and their interaction

• Prototype Applications

• Papers and Contact Information

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ResearchResearch GoalsGoalsMain Goals: • Design and implement a middleware to support the development

and deployment of such collaborative applications;• Experiment with new forms of context/location-aware collaboration,

develop applications using the middleware, and evaluate theirusability and usefulness.

Target setting:• Structured wireless network (802.11)• Users with laptops and palmtops• Intra-domain applications (e.g. for University campus-community,

corporation)

We called the middleware Mobile Collaboration Architecture (MoCA)

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MoCAMoCAMoCA consists of basic services for collecting and

processing context information, communication andclient/serverAPIs and a proxy Framework that facilitatethe use of these services by collaborative applications.

Essentially, the basic services support

• Distributed monitoring, storage and complex queriesabout the execution context of mobile devices.

• Advertisement and dynamic discovery of applications andmiddleware services.

•

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TheThe big Picturebig Picture

Client

Cm+ECIM

DS CIS CS

which CIS?

context

Appl?

req

subscr

req

event

reply mod_reply

LIS

COPS

Core Services

OptionalServices

Server

Cm+ECI

Server Server

Cm+ECI

ProxyFw

Application-specific adaptations

Application

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GlossaryGlossary

• Client and Server APIs• Cm: Communication Service• ECI: Event Communication Interface• M: Monitor/XP (also versions /Sim & /CE)• CS: Configuration Service• CIS: Context Information Service• LIS: Location Inference Service• DS: Discovery Service

• ProxyFw: Proxy Framework• COPS: Context Privacy Service

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MoCAMoCA´́ss PersonalitiesPersonalities

To widen the usability of MoCA’s core services, we have developed twoadditional programming interfaces personalities

• MoCA/MAX – for use with Agent Framework Jade

• MoCA/WS – for use as a Web Service

MoCA Core Services

MoCA/MAX MoCA/WS

Jade Application Java Application C# Application

SOAP/XMLFIPA Cm ECI(Pub/Sub)

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Communication APIsCommunication APIsCommunication Service (Cm):• Supports synchronous and asynchronous communication among

Java programs using both TCP or UDP

Event-based Communication Interface (ECI):• Supports asynchronous communication using the publish/subscribe

approach based on topics

• Through its API, a process can:– subscribe to events related to some topic (and satisfying an given SQL-

like expression) and/or – publish an event+message on a topic.

• An event provider is in charge of dispatching events to all subscribers which have subscribed to this event and whose expression is satisfied by the event properties.

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ECI ECI -- ExampleExampleSubscriber:

Topic topic = subscriber.subscribe(subject,expression);MyEventListener listener = new MyEventListener(); subscriber.addListener(listener, topic);

On occurrence of an event, ECI calls onReceiveData(Object), of listener, where Object contains event data.

Topic is any string, e.g. the device’s MAC-address (00:12:A9:41:AA:D6)Example of Expression: ((EnergyLevel < 65) or (FreeMemory < 18000) or ((OnLine = false)

and (DeltaT > 8000)) or (AdvertisementPeriodicity > 2))

public class MyEventListener implements EventListener { public void onReceiveData(Object data) {

Event receivedEvent = null; receivedEvent = (Event) data; String msg = (String) receivedEvent.getData(); System.out.println(listenerMsg + " received this msg from Event Server: " + msg);

} }

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ECI ECI -- ExampleExample

Publisher (Event Server):publisher = new EventProvider(localAddress,true); // create Event Provider on localhost:porteventProperty = new EventProperty(); // create Properties of an eventeventProperty.setBooleanProperty("OnLine",true);eventProperty.setLongProperty("deltaT",5000);eventProperty.setIntProperty("EnergyLevel",30);eventProperty.setIntProperty("FreeMemory",19000); eventProperty.setIntProperty("CPU",58);

// Publishes the event with a message to subscribers on a specific topicString topic = new String("00:12:A9:41:AA:D6"); publisher.publish(topic,eventProperty,msg);

But Event will be delivered only if eventProperties satisfy Expression

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ClientClient andand Server Server APIsAPIsThis APIs make the interaction with MoCA core services transparent to

the application.

Main functions:

• Gets addresses & register at MoCA core services (CIS, DS)

• Client gets address of CIS (and possibly, of a proxy);

• Starts the Monitor (Client only);

• Selects a protocol (sockets/TCP, sockets/UDP) for communicationwith the server or proxy;

• Embodies Cm and ECI APIs

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Core Core ServicesServices ofof MoCAMoCA• Monitor (at the mobile device):

– Is in charge of: (i) probing the state information (aka execution context) of the mobile device and (ii) sending this information to the ContextInformation Service (CIS) executing in the static network;

• Configuration Service (CS):– Stores and manages the configuration of each mobile device:

• MAC Address, (IP:port) pair of CIS, periodicity of the Monitor repots to the CIS, and (IP:port) pair of the Discovery Service;

• Context Information Service (CIS): – stores and processes the state information received from the Monitors,

and eventually sends notifications about context changes to Proxieswhich have subscribed to such notifications;

• Discovery Service (DS):– Accepts announcements of applications, and allows Clients to locate the

corresponding Servers and Proxies;

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Appl.Proxy

TypicalTypical PatternPattern ofof InteractionsInteractions

Applserver

DS

Appl.Proxy

CIS CS

Appl. Client

M

which CIS?context

Proxy?

req

Subscrclient

req

event

reply mod_reply

MoCA Services

Subscrclient event

Handover

register register

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MainMain ComponentsComponents• Monitor

– is a daemon executing on the mobile device;– Periodically polls (and sends to the CIS) state information about

the mobile device’s resources and wireless RF signals, e.g.: • Strength of RF signal received from all visible Access Points ;• CPU utilization, available memory and energy;• MAC Address, IP and currently used Access Point;

– RF signals are obtained through WiFi scan operations, in a uniform way, independently of the 802.11 network interface;

• Implemented for Linux, WinXP– The Monitor also reports to the CIS any change of the current IP

address or Access Point of the device (i.e. a migration)

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MonitorMonitor

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Context Information Service (CIS)Delivers context information to any application process (e.g.

server/client/proxies), through direct queries or subscriptions withcontext expressions.

• Context variables used in expressions• CPU (Int – 0 to 100) %• EnergyLevel (Int – 0 to 100) %• AdvertisementPeriodicity (Int – 0 to 100000)• APMacAddress (String)• FreeMemory (Long) in Kbytes• DeltaT (Long) in milliseconds• OnLine (Boolean)• IPChange (Boolean)• Roaming (Boolean)• RF Signal Strength from each AP (dB)

• Example of an expression: (Roaming = true) or ((OnLine = false) and (DeltaT > 10000))

• Usually, applications are interested in:– State of the device (e.g. available memory, enery level)– Wireless connectivity status– Aproximate position of the device

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Context Information Service (CIS)

CIS can be deployed as a pool of servers (each onecollecting the context information from Monitors);

• CIS-Monitor communication uses sockets/UDP;

• The proxies subscribe to the CIS informing the devices’s MAC-Address (as the Subject) and the Context-changeevents they are interested in (expressed in standardSQL92). Example:

Subject=”02:DA:20:3D:A1:2B”, Properties = “roaming = True” or “FreeMem < 15%” OR “CPU > 90%”;

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LocationLocation InferenceInference ServiceService (LIS)(LIS)LIS é um serviço para a inferência aproximada da localização de

dispositivos com interface 802.11 em ambientes indoor.Envolve duas etapas:Mapeamento/Calibração:• Mede-se a intensidade de sinal proveniente de todos os APs 802.11em

diversos Pontos de Referência (RP), que são armazenadas• A cada ponto de RP associa-se uma coordenada ou nome simbólico• Define-se as Regiões Simbólicas na àrea de interesse

Inferência:• Usando a diferença entre intensidade de sinal medida (também de todos os

APs) e as intensidades armazenadas, estima-se a distância que o dispositivo está dos n RP mais próximos,

• A fim de compensar variações do sinal, usa-se várias medidas e emprega-se um algoritmo estocástico (que compara probabilidades)

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{-59,-80,-49} {-63,-85,-57} {-42,-60,-60} {-30,-45,-64}

{-90,-75,-42} {-92,-72,-53} {-82,-50,-89} {-55,-35,-78}

{-75,-78,-68} {-76,-77,-74} {-54,-55,-70}

Room 501 Room 502 Room 503 Room 504

Room 505 Room 506 Room 507 Room 508

Corridor

Access Point

Reference Points {Signal Pattern}

Device

Location Inference Service (LIS)Location Inference Service (LIS)

{-60,-78,-48}

Inferred Device Location:Inferred Device Location:Room 501

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LIS LIS –– AcessoAcesso SSííncrononcronoManipuação da/Consulta sobre a hierarquia de regiões Simbólicas:• Region[] getAtomicRegions()

• void add(Hierarchy hierarchy)

• void remove(String hierarchyId)

• Hierarchy getHierarchy(String hierarchyId)

• List getAllHierarchies()

Consultas sobre Dispositivos em região e Região de um Dispositivo:• String getRegion(String deviceId, String hierarchyId)

• String[] getDevices()

• String[] getDevices(String regionId)

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LIS LIS –– Acesso AssAcesso AssííncrononcronoAplicação precisa instanciar um RegionListener e/ou um DeviceListener:

• void subscribe(String regionId, RegionListener listener)– onDeviceEntered(String regionId, String deviceId)– onDeviceExited(String regionId, String deviceId)

• void unsubscribe(String regionId, RegionListener listener)

• void subscribe(String deviceId, DeviceListener listener)– onRegionChanged(String deviceId, String regionId)– void unsubscribe(String deviceId, DeviceListener listener)

• void unsubscribe(String deviceId, DeviceListener listener)

Cada vez que um disp. entra ou deixa uma área o LIS notifica todas as aplicações registradas através do método onRegionChanged, informando o regionID e deviceID

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LIS FuncionamentoLIS FuncionamentoMonitor envia sinais a cada segundoA cada segundo LIS consulta CIS sobre sinais referente a todos os dispositivos

LIS mantém um cache da localidade mais recente de cada dispositivo, implementa o algoritmo de inferência, e gerencia hierarquia de áreas

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Proxy Proxy FrameworkFrameworkProxy is the element dealing with mobility-related tasks such as:

– Wired-wireless protocol translation– Caching/Hoarding during disconnection– Handover Management– Content Adaptation– Notice context changes and perform context-specific adaptations– ...

• But each collaborative application has specific demands;

• ProxyFramework is a “white-box” Application Framework which canbe customized to the specific application needs;

• Currently supports:– Content Adaptation (image, text)– Caching, triggered by disconnection

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Proxy (Proxy (FrameworkFramework) ) StructureStructure

ProtocolTranslation

CachingMngt

ProfileMngt

ContentAdaptation

HandoverMngt

AuthenticationSetup

Communication

ContextProcessing

EventDispatching

ContextProcessing

subscribe notifications

ServiceDiscovery

Server Client

Context Information Service

Frozen

Hot

Hot and Frozen Spots

subscribe

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Monitor/Monitor/SimSimIs a tool which simulates a mobile device:

• Behavior defined by a configuration file (scans are read from different files)

• Sends this information to CIS (like the “real” Monitor)

• Can be deployed on any host

This facilitates:

• Debugging of the context-aware applications in the usual networked environment (without having to physically move between regions)

• Evaluating the scalability of the application (test with hundreds/thousands of fake mobile devices)

monitor.scanInterval=1000 monitor.repeating=true cis.server.host=localhostcis.monitor.port=55010 file1=conf/Scan-Banco_01.txt interval1=5000 file2=conf/Scan-EspacoAberto.txt interval2=10000 file3=conf/Scan-Mesa_03.txt interval3=20000

loop

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Some Some PrototypePrototype ApplicationsApplicationsSome location-aware applications (prototypes) developed using MoCA:

• W-Chat chat-tool with connectivity awareness

• Notes in the Air (NITA) notes to locations (virtual whiteboards) and location-based chat

• Mobile Matchmaking Service location-based matching of userinterests

• BuddySpaceLive on-line tracking of friend’s locations

• Wireless Marketing Service (WMS) location-based discount coupons

• Virtual Lines location-based reservation of a position in a line

• Who Are You? (WAY) proximity-based exchange of business cards

• ...

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WW--ChatChat

Wireless Chat (W-Chat) shares the wireless connectivitystatus of the participants of a chat room;

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UbiquitousUbiquitous GuideGuide -- uGuideuGuide

• Client/Server application

• Admin registers at the serverone URL for each symbolicregion

• Symbolic Regions may berepresentend in an hierarchy, e.g.

/PUC-Rio/RDCBuilding/5thfloor/Room511

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uGuideuGuide atat thethe ClientClient• User logs in • Icon appears in task-bar• Whenever user enters a

registered region, a pop-upopens with the correspondinglink

• Link can be opened in anyWeb browser

• Perhaps, user enters a nonregistered region

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SelectedSelected PublicationsPublications(available at www.inf.puc-rio.br/~endler/publ.html)

Overview:• V. Sacramento, M. Endler, H.K. Rubinsztejn, L.S. Lima, K. Gonçalves, F.N.do Nascimento, G.

Bueno, MoCA: A Middleware for Developing Collaborative Applications for Mobile UsersIEEE Distributed Systems Online, ISSN 1541-4922, vol. 5, no. 10, October, 2004.

LIS and NITA:• K. Gonçalves, H.K. Rubinsztejn, M. Endler, B. Santana, S.D.J. Barbosa, Um aplicativo para

comunicacão baseada em localização, 6o. Workshop de Comunicação sem Fio e ComputaçãoMóvel (WCSF 2004), Fortaleza, pages 225-231, October 2004.

• H.K. Rubinsztejn, M. Endler, V. Sacramento, K. Gonçalves, F.N. do Nascimento, Support for Context-aware Collaboration, First International Workshop on Mobility Aware Technologies and Applications (MATA 2004), Florianópolis, LNCS no. 3284, pages 37-47, October, 2004

Proxy Framework:• H.K. Rubinsztejn, M. Endler, N. Rodrigues, A Framework for Building Customized Adaptation

Proxies, in Proc. of the IFIP conference on Intelligence in Communication Systems (INTELLCOMM 2005) (to appear), Montreal, October 2005.

Context Privacy:• V. Sacramento, M. Endler, F.N do Nascimento, A Privacy Service for Context-Aware Mobile

Computing, Proc. of the IEEE Conference on Security and Privacy for Emerging Areas in Communication Networks (to appear), Athens, September 2005.

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MoCAMoCA –– CurrentCurrent StatusStatusImplementation (docu): online:

Monitor/XP (OK)Monitor/SimConfiguration Service - CS (OK) cs.lac.inf.puc-rio.br:

55015 (Mngt), 55016 (M)Context Information Service - CIS (OK) cis.lac.puc-rio.br:

55010(M);55000(pub);55001(query)Location Inference Service - LIS (OK) lis.lac.inf.puc-rio.br:

55020(pub);55021(query)Discovery Service -DSClient API (OK)

Synchronous &Asynchronous

Server API (OK)Synchronous & Asynchronous

EventService – ECI (OK)

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WorkWork in in ProgressProgress• Flexibilization of CIS with new tags (e.g. transmission

rate, GPS, etc.)

• Monitor/CE and Communication API for Windows Mobile

• Mechanism for measuring link quality (transmission rate)

• uGuide/CE for portables

• Integration of LIS with GPS-based positioning

• Framework for Context-aware workflows for m-commerce

• A tool for evolutionary and heterogeneous contextmanagement

• Mechanism for detecting stability of basic contextreadings

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CreditsCreditsThe Middleware Team:

• Vagner Sacramento

• Hana K. Rubinsztejn

• Ricardo C.A. da Rocha

• Luciana dos S. Lima

• José Viterbo

• Fernando Ney Nascimento

• Gustavo Luis Baptista

• Marcelo Malcher

The Application Folks:

• Kleder Gonçalves

• Pedro Neves

• Rodrigo Prestes

• Fabio Bruno Pereira

• João Paulo Braga

Other Collaborators:

• Daniel Fleischmann (Gr)

• Giulliano Bueno (Gr)

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More More InformationInformation......For documentation and downloads visit MoCA’s Web Site:

www.lac.inf.puc-rio.br/moca

Send Email to:

info@lac.inf.puc-rio.br