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DBGlobe IST-2001-32645. Evaggelia Pitoura, UoI, Greece. 1 st Year Review, Cyprus, January 31, 2003. Proactive initiative on: Global Computing (GC). Future and Emerging Technologies (FET). The roots of innovation. Outline. General Introduction Dissemination and Self-Assessment
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DBGlobe IST-2001-32645 Evaggelia Pitoura, UoI, Greece 1st Year Review, Cyprus, January 31, 2003 Proactive initiative on: Global Computing (GC) Future and Emerging Technologies (FET) The roots of innovation
Outline General Introduction Dissemination and Self-Assessment Individual Presentations (per WP) Future Directions for Next Year DBGlobe, 1st Annual Review Paphos, Jan 2003
DBGlobe: Introduction DBGlobe, 1st Annual Review Paphos, Jan 2003
The Vision of Global Computing: In the near future, there will be increasingly powerful computers in smart cards, telephones, and other information appliances. Smart buildings will put computers in light switches, vending machines, and home appliances. Software objects, in the form of mobile software agents, will roam the Internet. This will create a massive infrastructure composed of highly diverse interconnected mobile entities. GC INITIATIVE:The ultimate goal of the research action is to provide a solid scientific foundation for the design of such systems, and to lay the groundwork for achieving effective principles for building and analysing such systems.
Why DBGlobe? On the premise,global computing is a database problem: how to design, build and analyze systems that manage large amount of data A Data-Centric Approach: autonomous mobile entities handle (possess, produce, need, use) data data (metadata) describe the entities Our focus: How to store, index, disseminate, discover, query data in global computing The traditional database approach of storing data of interest in monolithic database management systems becomes obsolete DBGlobe, 1st Annual Review Paphos, Jan 30, 2003
Why DBGlobe? • In GC, autonomous computational entities, not centrally controlledactivitythus massive distribution, heterogeneity, & autonomy In traditional db research, centralized or small scale distribution/relatively homogeneous, full control • In GC, mobilecomputational entities In traditional db research, passive data and data sources, in that they remain unchanged unless explicitly updated • In GC, the configuration varies over time In traditional db research, static (their location remains fixed). • In GC, systems operate with incomplete information about the environment In traditional db research, exact knowledge as opposed to discovery, filtering New research problems in all aspects of data management: modeling, dissemination, storage, and querying Paphos, Jan 2003 DBGlobe, 1st Annual Review
Overview The DBGlobe project aims at developing novel data management techniques to deal with the challenge of global computing Partners: Univ. of Ioannina, GR (coordinator) INRIA, FR CTI, GR AUEB, GR Univ. of Cyprus, CY Univ. of California at Riverside, USA Subcontractors, Technical University of Crete, GR Aalborg University, DK Paphos, Jan 2003 DBGlobe, 1st Annual Review
A quick look … Work divided in 6 Work Packages (WP) WP1: System Architecture (main system components, metadata, distribution) WP3: Data Delivery and Coordination (means to delivery data, how to coordinate execution) WP4: Querying and Information Discovery (how to discover data, how to query) WP2: Simulation Environment (provide an environment for simulation work) WP5: Proof-of-Concept (build a prototype context-aware applications) WP6: Project Management DBGlobe, 1st Annual Review Paphos, Jan 2003
Timeline … Year 1 Year 2 WP6: Management WP5: Proof-of-Concept Prototype WP4: Information Discovery and Querying WP3: Data Delivery & Coordination WP2: Simulation WP1: System Architecture 15 18 21 24 3 6 9 12 DBGlobe, 1st Annual Review Paphos, Jan 2003
A quick look … Overview per Work Package .. More on the results in the talks that will follow … DBGlobe, 1st Annual Review Paphos, Jan 2003
Data centric Approach • mobile entities as primary data stores, • mobile entities as mini-servers (computational entities) that protect and encapsulate access to their data • ad-hoc distributed database systems of unprecedented scale • Meta-information and services: • Storage Components that hold metadata about mobile objects • Server Components that provide services for and about the mobile objects. • a backbone of metadata information and services to reason about and query the behaviour and state of the autonomous mobile entities. Paphos, Jan 2003 DBGlobe, 1st Annual Review
System Architecture (WP1) Objectives • Specification of the requirements of the system • Metadata definition • Determining of policies for replicating, caching and aggregating data and metadata across the network sites of the system • Overall System Design DBGlobe, 1st Annual Review Paphos, Jan 2003
System Architecture (WP1) System Architectures:No centralized database server, instead, each mobile object constitutes a database of each own. PMOs (Primary Mobile Objects) PMO PMO PMO • Data-centric • PMOs as primary data stores • PMOs as computational entities that protect and encapsulate access to their data Communities: clustering of data and services based on “context”, e.g., location DBGlobe, 1st Annual Review Paphos, Jan 2003
WP1: System Architecture Service-Oriented Approach Data encapsulated within services Why services: interoperability respect autonomy of PMOs can be composed distributed execution security Users interact with the system through AXML queries, Active XML incorporates calls to services and XQuery (XML query language)
WP1: System Architecture AXML Query Ontologies/Metadata/Semantic Context Semantic Layer Infrastructure context (device metadata, location mangement) Indexes/replication/caching System Layer DBGlobe, 1st Annual Review Paphos, Jan 2003
WP1: System Architecture DBGlobe architecture • Infrastructure • PMOs are organized according to spatial proximity into cells • Cell Administration Servers (CAS) manage sets of cells and the PMOs located within them • Middleware • Community Administration Servers (CoAS): semantic grouping of PMOs and associated data and services according to context • User Agents represent the user (PMO) (for example, in case of network disconnections) DBGlobe, 1st Annual Review Paphos, Jan 2003
WP1: System Architecture Service Creation and Discovery Composition of Services and Semantic Service Matching • Parameter ontology covering all the parameters used in the various services • Service ontology supports the structuring of services and aids service discovery DBGlobe, 1st Annual Review Paphos, Jan 2003
WP1: System Architecture Profile Data - User Profile Users have preferences with respect to what information they usually request, and considering mobility, as to when and to where Profile Data - Device Profile • Data that characterizes the PMO • The characteristics of the device itself, • e.g., screen size, memory, keyboard, processor power • The characteristics of the device with respect to the DBGlobe system • e.g., credentials, after registering with the DBGlobe network, a schedule for the availability of data
WP1: System Architecture Profiles - Movement • User and device profiles contain spatiotemporal data about moving objects • Definition of a mobile ontology to record • the trajectory (movement) • properties of the trajectory (e.g., speed, heading) • relationships among trajectories (e.g., meet, intersect) • relationships with environment (e.g., cross) DBGlobe, 1st Annual Review Paphos, Jan 2003
WP2: Simulator Simulation Environment (WP2) Objective Build a simulator for such dynamic environments and use it to test our protocols Current Status Our current simulator supports the basic functionality of CAS Networking, mobility management, service registration and invocation DBGlobe, 1st Annual Review Paphos, Jan 2003
The DBGlobe Project: WP1 & WP2 • Summary • Distribution of “infrastructure components” (CAS) based on geographical proximity • Distribution of “middleware” components (CoAS) based on context proximity • Analysis of metadata (service and parameter ontology, mobile ontology, profile and content metadata) • Bloom-based summaries of indexes for distributed service discovery • Initial results on content caching • Replication of services (more later on AXML) • Working simulator that provides basic system support and proof-of-concept implementation work on specific aspects
Publications (WP1 and WP2) • A. Karakasidis and E. Pitoura, “DBGlobe: A Data-Centric Approach to Global Computing”. International Workshop on Smart Appliances and Wearable Computing (IWSAWC 2002). In conjunction with ICDCS 2002, Vienna, Austria, July 2002 • D. Pfoser, E. Pitoura, and N. Tryfona. “Metadata Modeling in a Global Computing Environment”. Proc. of the 10th ACM International Symposium on Advances in Geographic Information Systems, McLean, VA November 8-9, 2002. • 3. S. Valavanis, M. Vazirgianis, and K. Norvag, “MobiShare: Sharing Context-Dependent Data and Services from Mobile Sources”. Submitted for publication • 4. C. Ververidis, S. Valavanis, M. Vazirgiannis, G.C. Polyzos, “An Architecture for Sharing, Discovering and Accessing Mobile Data and Services: Location and Mobility Issues”, Presented at: Lobster Workshop, LBS for accelerating the European-wide deployment of Services for the Mobile User and worker, Mykonos, Greece, 4-5 October, 2002, http://www.iit.demokritos.gr/lobster/lobster_mykonos2002.html
Publications (WP1) 6. P. Triantafillou and I. Aekaterinides, “Web Proxy Cache Replacement: Do's, Don'ts and Expectations”. Submitted for Publication 7. P. Triantafillou and I. Aekaterinides, “Web Proxy Cache Placement, Replacement and the Proxy Teller”, Submitted for Publication 8. G. Koloniari and E. Pitoura, “Bloom-based Filters for Hierarchical Data”, Submitted for Publication 9. G. Kastidou, E. Pitoura and G. Samaras, “A Scalable Mobile Agent Location Mechanism”, Accepted for Publication 1st International Workshop on Mobile Distributed Computing (MDC'03), May 19, 2003, held in conjunction with the 23rd International Conference on Distributed Computing Systems (ICDCS'03), To appear 2003. A paper on the overall DBGlobe architecture, by all partners, in preparation
The DBGlobe Project: WP3 Work Outline (WP3) • Data Delivery/Coordination • Data delivery among the system components: (a) the mobile entities, (b) the servers and (c) the users. Derive adaptive data delivery mechanisms that will combine various mode of delivery such as • push (transmission of data without an explicit request) and pull, • periodic and aperiodic , as well as • multicast and unicast delivery. • Model the coordination of the mobile entities using workflow management and transaction management techniques that have been used in the multi-agent community. DBGlobe, 1st Annual Review Paphos, Jan 2003
The DBGlobe Project: WP3 Outcomes of WP3 so far: D8: Data Delivery Mechanisms A taxonomy of mechanisms An outline of potential use within the DBGlobe architecture • A number of specific results in data delivery: • Coherent Push-based Data Delivery • Adaptive Multi-version Broadcast Data Delivery • Efficient Publish-Subscribe Data Delivery DBGlobe, 1st Annual Review Paphos, Jan 2003
The DBGlobe Project: WP3 Taxonomy of Different Modes of Data Delivery push Publish/subscribe (aperiodic, 1-N, push) Email list ( aperiodic, unicast, push) pull Polling ( periodic, unicast, pull) 1-N broadcast unicast periodic aperiodic Request/Response (aperiodic, unicast, pull) DBGlobe, 1st Annual Review Paphos, Jan 2003
The DBGlobe Project: WP3 The Data Broadcast Push Model • The server broadcasts data from a database to a large number of clients • push mode + no direct communication with the server (stateless server, e.g., sensors) • “client-side” protocols • Data updates at the server • Periodic updates for the values on the channel Broadcast Channel Server Client • Efficient way to disseminate information to large client populations with similar interests • Physical support in wireless networks (satellite, cellular) • Various other applications, sensor networks, data streams
The DBGlobe Project: WP3 Coherent Data Delivery Ensure that clients receive temporally coherent (e.g., current) and semantically coherent (transaction-wise) data • Provide a model for temporal and semantic coherency • Show what type of coherency we get if there are no additional protocols • Show what type of coherency is achieved by a number of protocols proposed in the literature (and their extensions)
The DBGlobe Project: WP3 AdaptiveMulti-Version Broadcast • The server (data source) at each cycle sends not just one value per item but instead multiple versions per item • Explore multiple versions for increasing client concurrency and disconnections: develop protocols and evaluate their performance • Access multiple server states at the same time: access to data series when not enough memory or • Multiple data servers share the channel (multi-sensors networks), that is multiplexing data from a number of sensors
The DBGlobe Project: WP3 Issues How should the broadcast be organized? select the order according to which items are broadcast What are appropriate client-cache protocols? • We have developed • broadcast organizations and • client cache replacement policies that adapt to the client access behaviour • We have proposed data compression schemes DBGlobe, 1st Annual Report Paphos, Jan 2003
The DBGlobe Project: WP3 Subscription Framework in DBGlobe • Personalized Information Delivery: Pub/Sub Systems • Subscriptions of services • Events: service calls • Match: events to all subscriptions impacted • Key problems when designing and implementing large-scale publish/subscribe systems • efficient propagation of subscriptions and • distributed event processing among the servers of the system DBGlobe, 1st Annual Report Paphos, Jan 2003
The DBGlobe Project: WP3 Contributions • Motivation: Develop data structures and algorithms that can introduce significantly more efficient • subscription propagation, • event processing, and • event matching/filtering. • Key idea: Summarize subscriptions and … process summaries as opposed to subscriptions.
Publications (WP3) E. Pitoura and P. Chrysanthis. “Multiversion Data Broadcast”, IEEE Transactions on Computers, 51(10):1224-1230, October, 2002 E. Pitoura, P. K. Chrysanthis and K. Ramamritham. “Characterizing the Temporal and Semantic Coherency of Broadcast-based Data Dissemination”. Proc. of the 9th International Conference on Database Theory, January 2003, Siena, Italy. O. Shigiltchoff, P. Chrysanthis and E. Pitoura. “Multi-version Data Broadcast Organizations”. In Proc. of the 6th East European Conference on Advances in Databases and Information Systems (ADBIS), September 2002, Bratislava, Slovakia P. Triantafillou and A. Economides, “Subscription Summaries for Scalability and Efficiency in Publish/Subscribe Systems”, 1st Intl. IEEE Workshop on Distributed Event-based Systems, (DEBS02) July 2002. P. Triantafillou and A. Economides, “Efficient Distributed Event Processing using Subscription Summaries in Large Scale Publish/Subscribe System”, Submitted for Publication.
Work Outline (WP4) • Querying: Data exchange and computation in the background in response to cues or queries from users. On a multitude of databases (networked mobile processing entities and their data) • New query language modelling abstractions that will: • include a knowledge acquisition component, no exact knowledge of the data schema, information may be incomplete. High update rate (of both data values and context information) • incorporate filtering, • Be context-aware, to deal with the scale and complexity of the environment. • Query execution models for such dynamic environments of numerous processing entities. DBGlobe IST-2001-32645 Paphos, Jan 2003
The DBGlobe Project: WP4 AXML Documents • May contain calls to any SOAP web service • e-bay.net, google.com, babel.org, etc. • AXML peers also offer web services. • Locally defined services can be called. <knownAuctions ID="peer10"> <category name="Toys"> <sc>eBay.net/getOffers("Toys")</sc> <auction id="1254" > <heldBy>eBay.net</heldBy> <item>Pink panther</item> </auction> … <sc>babel.org/translate("Czech", "English", <sc>crystal.cz/getToys()</sc>)</sc> <sc>peer25/getAuctions([../@name])</sc> </category> ... <sc frequency="once" >getMyAuctions()</sc> … </knownAuctions> • Are enriched by each service call's results • The returned nodes are inserted as brothers of the corresponding <sc> element. • Can use XPath expressions for call parameters • Relative path expressions are evaluated starting from the <sc> element. • Activation of calls and data lifespan are controlled • frequency: when is the service called ? • validity: how long is the retrieved data kept ? • mode: immediate or lazy ? AXML Documents are powerful data integrators.
The DBGlobe Project: WP4 Outline • Distribution and replication • distributethe load among devices, by: • Using several services • Distributing documents across several devices. • replicate documents and services, to allow for “local” computation location-aware extension of XQuery to handle distributed/replicated data and services. A cost model for the global computing context, measuring the “observable performance” of each site An algorithm • Security and capabilities Based on types DBGlobe IST-2001-32645 Paphos, Jan 2003
The DBGlobe Project: WP4 Publications (WP4) S. Abiteboul, O. Benjelloun, I. Manolescu, T. Milo and R. Weber, “Active XML: Peer-to-Peer Data and Web Services Integration (demo)”, Proceedings of the 28th VLDB Conference, Hong Kong, 2002. T. Milo, S. Abiteboul, B. Amman, O. Benjelloun, F. Dang and Ngoc, “Exchanging Intentional XML Data”, SIGMOD 2003 S. Abiteboul, A. Bonifati, G. Cobena, I. Manolescu and T. Milo, “Dynamic XML Documents with Distribution and Replication”, SIGMOD 2003 DBGlobe IST-2001-32645 Paphos, Jan 2003
Work Outline (WP5) implement a proof-of-concept prototype location-aware queries DBGlobe, 1st Annual Review Paphos, Jan 2003
The DBGlobe Project: WP5 Initial Results Exploitation of Materialized Views (implemented through mobile agents) for supporting CoAS Initial implementation of context-aware portals for wireless users DBGlobe, 1st Annual Review Paphos, Jan 2003
Publications (WP5) C. Panayiotou, G. Samaras, “Personalized Portals for the Wireless User Based on Mobile Agents: Demonstration“, Accepted for Publication, 19th International Conference on Data Engineering, Sponsored by the IEEE Computer Society, March 5 - March 8, 2003 - Bangalore, India. To appear 2003. G. Samaras, C. Panayiotou, "A Flexible Personalization Architecture for Wireless Internet Based on Mobile Agents", Proc. 6th East-European Conference on Advances in Databases and Information Systems (ADBIS 2002), September 2002, Bratislava, Slovakia. G. Samaras, C. Spyrou, E. Pitoura, “View Generator (VG): A Mobile Agent Based System for the Creation and Maintenance of Web Views”, 7th IEEE Symposium on Computers and Communications, Taormina, Italy July 2002. G. Samaras, K. Karenos, P. K. Chrysanthis and E. Pitoura. “ViSMA: Implementation of an Extendible Mobile-Agent Based System for the Materialization and Maintenance of Personalized and Shareable Web Views” (Demo). Submitted for publication
Management Deliverables Meetings Budget DBGlobe, 1st Annual Review Paphos, Jan 2003
Technical Deliverables: Year 1 DBGlobe, 1st Annual Review Paphos, Jan 2003
Technical Deliverables: Year 2 DBGlobe, 1st Annual Review Paphos, Jan 2003
General Deliverables (WP6): Year 1 DBGlobe, 1st Annual Review Paphos, Jan 2003
General Deliverables (WP6): Year 2 DBGlobe, 1st Annual Review Paphos, Jan 2003
Meetings Three Project Meetings in 2002 Kick-off meeting, Jan 11, Athens 2nd Meeting, May 27-28, Ioannina 3rd Meeting, Nov 29, Athens presentations at the web page A number of Working Groups Meetings AUEB – UoI, Ioannina AUEB – CTI, Athens
Workpackage No and Title Lead Partner Persons-months per participant for the first year UOI INRIA CTI AUEB UCY UCR WP1: System Architecture CTI 7.0 8.0 11.0 - 1.0 4.0 WP2: Simulation Environment AUEB 4.0 - 1.0 7.78 3.0 1.0 WP3: Data Delivery and Coordination UoI 8.025 2.0 - 4.35 2.0 1.0 WP4: Information Discovery and Querying INRIA 1.0 9.0 - 1.98 1.5 - WP5: Proof-of-concept Prototype: Location-Aware Querying UCY 1.0 - - 1.0 2.5 - WP6: Project Management and Dissemination of Results UoI 6.0 - - - - - Effort
Dissemination Publications Web Page Events DBGlobe, 1st Annual Review Paphos, Jan 2003
Publications (WP1 and WP2) A. Karakasidis and E. Pitoura, “DBGlobe: A Data-Centric Approach to Global Computing”. International Workshop on Smart Appliances and Wearable Computing (IWSAWC 2002). In conjunction with ICDCS 2002, Vienna, Austria, July 2002 S. Valavanis, M. Vazirgianis, and K. Norvag, “ MobiShare: Sharing Context-Dependent Data and Services from Mobile Sources”. Submitted for publication C. Ververidis, S. Valavanis, M. Vazirgiannis, G.C. Polyzos, “An Architecture for Sharing, Discovering and Accessing Mobile Data and Services: Location and Mobility Issues”, Presented at: Lobster Workshop, LBS for accelerating the European-wide deployment of Services for the Mobile User and worker, Mykonos, Greece, 4-5 October, 2002, http://www.iit.demokritos.gr/lobster/lobster_mykonos2002.html
Publications (WP1) P. Triantafillou and I. Aekaterinides, “Web Proxy Cache Replacement: Do's, Don'ts and Expectations”. Submitted for Publication P. Triantafillou and I. Aekaterinides, “Web Proxy Cache Placement, Replacement and the Proxy Teller”, Submitted for Publication D. Pfoser, E. Pitoura, and N. Tryfona. “Metadata Modeling in a Global Computing Environment”. Proc. of the 10th ACM International Symposium on Advances in Geographic Information Systems, McLean, VA November 8-9, 2002. A paper on the overall DBGlobe architecture, all partners, in preparation