1. Future and Emerging Technologies (FET) Future and Emerging Technologies (FET) The roots of innovation Proactive initiative on: Global Computing (GC) Proactive initiative on: Global Computing (GC) 1 st Year Review, Cyprus, January 31, 2003 DBGlobe IST-2001-32645 WP1 - System Architecture

2. DBGlobe Midterm Review, WP 12 DBGlobe WP1 - System Architecture Dieter Pfoser CTI, Greece

3. DBGlobe Midterm Review, WP 13 Objectives WP 1 - System Architecture n To derive appropriate architectures for ad-hoc databases of mobile entities. Such architectures should be metadata driven. In particular, – to define what is the appropriate metadata information to describe mobile entities; such metadata must include information at various levels of detail, – to derive an appropriate metadata definition and manipulation language, – to design distribution and replication protocols, – to make the architectures dynamically configurable and extensible, and – to achieve fault-tolerance and availability.

4. DBGlobe Midterm Review, WP 14 Outline n Introduction n Architecture – Infrastructure – Middleware n Semantic Information – Profile data – Content metadata n Parameter ontology n Service ontology – Local vs. global metadata

5. DBGlobe Midterm Review, WP 15 Introduction n DBGlobe is a data and service management system for ubiquitous computing n Service-oriented approach, data are wrapped as services n PMOs – “walking” miniature databases – service providers and/or service requestors – register services through content metadata n DBGlobe infrastructure has to provide the “glue” for the PMOs to act as a single data source

6. DBGlobe Midterm Review, WP 16 Architecture Proposal n Infrastructure (essential functionality) – PMO components – PMOs are organized according to spatial proximity in cells – Cell Administration Servers (CAS), administrative grouping manage sets of cells and the within located PMOs n Middleware (common needed functionality) – Community Admin. Server (CoAS), semantic grouping of PMOs according to communities – User agents, supports PMOs that have limited resources and/or are offline – Dynamic results database

7. DBGlobe Midterm Review, WP 17 PMO Components n “Small” computing devices n Service Request Definition Tool – specify the services, discover and invoke them n Service Definition Tool – create and publish services n Media Previewer – displaying, e.g., images, sound, movies n Service Engine – to run services

8. DBGlobe Midterm Review, WP 18 Space Model Geographical 2-D space is divided into administrative areas (grid), each managed by an Cell Administration Server (CAS) – Similar topology to cellular systems – Heterogeneous (cell size, technologies…) CAS

9. DBGlobe Midterm Review, WP 19 Cell Administration Server (CAS) n CAS manages sets of PMO according to spatial distribution n Connect PMOs to the network n CASes are interconnected through a network, e.g., Internet – Aware of their CAS neighborhood – Cooperate, e.g., forwarding of service descriptions, handling of requests

10. DBGlobe Midterm Review, WP 110 Cell Administration Server Service Discovery, Execution PMO connectivity handling CAS network Service profiling DBGlobe cloud

11. DBGlobe Midterm Review, WP 111 Community Administration Server (CoAS) n CAS groups PMOs according to network topology (admin. grouping) n CoAS, semantic grouping of PMOs in communities (groups of PMOs having the same “interest”) n Contains constructs to facilitate – Service creation – Service discovery (to handle requests, browsing, creation) – Ontologies

12. DBGlobe Midterm Review, WP 112 Outline n Introduction n Architecture – Infrastructure – Middleware n Semantic Information – Profile data – Content metadata n Parameter ontology n Service ontology – Local vs. global metadata

13. DBGlobe Midterm Review, WP 113 Profile Data - Device Profile n Data that characterizes the PMO 1. The characteristics of the device itself n e.g., screen size, memory, keyboard, processor power 2. The characteristics of the device with respect to the DBGlobe system n e.g., credentials, after registering with the DB- Globe system, a schedule for the availability of data

14. DBGlobe Midterm Review, WP 114 Profile Data - User Profile n Users have preferences with respect to what information they usually request, and n considering mobility, as to when and to where they do this n Creation of profile – Explicitly defined by the user – Implicitly by user behavior patters n Spatiotemporal behavior (mobile ontology based on trajectories) n Previous choices n I.e., we (the PMO) records user behavior in terms of movement and information access

15. DBGlobe Midterm Review, WP 115 Content Metadata n Service-oriented approach, data are wrapped as services n Support of service creation and discovery n Parameter ontology – covering all the parameters used in the various services – supports service creation n Service ontology – structuring of the services – supports service discovery

16. DBGlobe Midterm Review, WP 116 Parameter Ontology n A service can be based on (i) only data, (ii) other services, or (iii) services and data n Services have an interface consisting of a set parameters n Support the construction of new services by describing the parameters of services in terms of a (global?) ontology n Example: we want to extend a weather service (A) to provide weather information along a route (A*) – (A) Weather: (location, time  weather) – (A*)Weather_en_route: (route  {weather}).

17. DBGlobe Midterm Review, WP 117 Growing Parameter Ontology n Parameter ontology can be seen as FUP (Frequently Used Parameters) n Services are defined evolutionary, and so is the parameter ontology n One could see services as an aid to gradually denote data semantics

18. DBGlobe Midterm Review, WP 118 Service Ontology n A service is semantically more than the sum of its parts (parameters) n Knowing the semantics of the parameters of the service is not sufficient to reason about the semantics of the service and to locate a service that fits user queries n Service discovery, a means to discover and/or relate services, a service ontology is needed n UDDI?

19. DBGlobe Midterm Review, WP 119 Service Ontology (cont’d) n Tree structure n Classification of services into nodes that form a specialization hierarchy n Services are connected to nodes (n:m relationship) n Nodes characterize services, e.g., using keywords

20. DBGlobe Midterm Review, WP 120 Service Ontology Example n Service ontology contains a large number of services  service browsing unrealistic n Based on keywords n Thesaurus is used to find entry points to structure n Example: request for “travel, taxi, booking” service, search for close-by appearance of keywords along a path travel - cityguides - mass transp. info - taxi yellow pages travel - reservation|booking - taxis

21. DBGlobe Midterm Review, WP 121 Local vs. Global Ontologies n Defining global ontologies is difficult n Communities share a common interest, easier at this local level

22. DBGlobe Midterm Review, WP 122 Conclusions and Future Work n Architecture (CAS - administrative aspect and CoAS - semantic aspect) n Metadata, profile data and ontologies to support service creation and discovery n Making local constructs go global, I.e, towards a global service ontology n Integration of ontologies in prototype implementation n Empirical evaluation, I.e., how difficult is authoring services, will they ever do it?

23. DBGlobe Midterm Review, WP 123 Publications n Karakasidis and E. Pitoura, “DBGlobe: A Data-Centric Approach to Global Computing”. IWSAWC 2002, Vienna, Austria, July 2002 n S. Valavanis, M. Vazirgianis, and K. Norvag, “ MobiShare: Sharing Context-Dependent Data and Services from Mobile Sources”. Submitted for publication n 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, Mykonos, Greece, 4-5 October, 2002 n D. Pfoser, E. Pitoura, and N. Tryfona. “Metadata Modeling in a Global Computing Environment”. Proc. 10th ACM GIS, McLean, VA November 8-9, 2002. n G. Samaras, C. Panayiotou, “A Flexible Personalization Architecture for Wireless Internet Based on Mobile Agents”, Proc. ADBIS 2002, September 2002, Bratislava, Slovakia. n C. Panayiotou, G. Samaras, “Personalized Portals for the Wireless User Based on Mobile Agents: Demonstration“, Accepted for Publication, 19th ICDE, 2003 - Bangalore, India. To appear 2003.

24. DBGlobe Midterm Review, WP 124 Meeting the Objectives n The overall architecture of the DBGlobe system (deliverable D3 - Section 2, and three research publications) n The design of the metadata management system (deliverable D2, and one research publication) n A detailed specification of DBGlobe's functional components (deliverable D3) n Appropriate distribution, caching and replication protocols and location management (6 research publications).