Communities on DBGlobe System

1. Communities on DBGlobe System Hara Skouteli George Samaras Other Contributors Chris Panagiotoy Elina Charalambus

2. Objectives of WP5: • To demonstrate through a concrete example the idea of ad-hoc databases and the various forms of querying • To capture, design and implement a location-aware system===> concept aware systems • Location is a concept

3. Context: how do we define "context", what is it? • Context is any information that can be used to characterize the situation of an entity. An entity is • a person, • place, • or object

4. Context based queries • With Context based queries we query data around a context, e.g. human habits. • With Context containment queries we aim to contain the results of the query within the boundaries of a specific contextual concept, e.g., location is such one concept • The data that are queried are related to a specific concept, either directly or indirectly.

5. Continues queries • A continual query is a standing query that monitors updates of interest using distributed triggers and notifies the user of changes whenever an update of interest reaches specified thresholds or some time limit is reached. • We want to promote Concept-based Continuous Containment Queries

6. DBGlobe Architecture and Context Queries • DBGlobe Architecture is consisted by: • PMOs • CASs • CASs can support location aware queries because they can provide the location information of any device

7. However…… • Context is not only location • In DBGlobe environment, mobile users provide and request services • This dynamic environment is more exigent than the classic mobile environments where only the requesters can move around. • We need a fast and efficient way to find and query data and services available to PMOs, in order to replace an unavailable service. • We expand the DBGlobe architecture by introducing the notion of Communities around specific concepts.

8. CAS CoAS Objectives of Communities Communities can be seen as ad-hoc databases of service, users or device ontologies • Each ontology may participate to one or more communities. • Thus the DBGlobe domain is divided to sub-domains that are managed from the Community Administrator Servers. • Each Community Server covers all CAS, and each CAS can be covered by many Community Administrator Servers.

9. Community Administrator Server (CoAS) • Community Administrator Servers (CoAS) are interconnected through a network • Their major objective is to create communities of services, users, and devices around a concept. • The total number of CoAS are organized in a tree structure. • Each CoAS knows its own children and father. Each child serves a sub-concept of its father. • Whenever the community exceeds a number of ontologies the community can be split to sub-communities. Info Community Finance Community Sports Community news Community Basketball Community The type of objects Keywords Related communities

10. Community Ontology • Each Community is described by an ontology that better mirroring the purpose of the community. • The ontology that describes the community includes • The type of objects that are allowed to join the community, (PMO profiles, User profiles, service profiles) • Keywords classified in tree form to describe the objective of the community, those keywords are divided to three categories keywords for PMOs, for Services, for Users. • Related communities. In [10] is used an similar approach to represent entities. Community Ontology Object types: PMOs, services, users Keywords: PMOs: PDA,Laptop Users: photographer Services: photos, videos Related Communities: Painting Community …………………….

11. PMO Ontology Directory User Ontology Directory Service Ontology Directory Available data are: • PMO metadata • User profile metadata, • service ontology metadata. • The main components of the CoAS manage the three types of Directories • The information contained in those Directories is retrieved from the CASs of the DBGlobe architecture.

12. Finance Community Info Community Finance Community Sports Community news Community Basketball Community PMO Ontology Node Community Taxonomy Trees • Since we have three different categories of metadata, each CoAS maintains tree different directories: one for each category. • Each internal node of the taxonomy tree keeps the community description (ontology) • The leaf nodes store an identifier of the user, device or service (PMO) ontology that belongs to the community, • unique device id • user id • service name and provider. Tree of Community Ontology

13. PMO Ontology Directory User Ontology Directory Service Ontology Directory CoAS Architecture • In detail, the components that comprise a CoAS are the following: • The PMO Ontology Directory lists all PMOs which belongs to the community • The User Ontology Directory lists all users which belongs to the community • The Service ontology Directory lists all services which belongs to the community • CAS directory lists all the system CASs. A CoAS retrieves information from any CAS • CoAS directory lists other CoAS (father and children). This directory is necessary in the case that the CoAS is not able to satisfy a query or a sub-query; the query will be forwarded to another CoAS to execute it. In order to forward query are used summaries to find the possible CoAS that can satisfy the query. • Query executoris a very important component of the CoAS, this component is responsible to accept a query from the Server Manager, to fragment it and forward each fragment to the appropriate taxonomy tree in order to be executed. • Concept Alerts Directoryis used to better support continues queries by providing triggers for them. It keeps a set of context information that may change during time and the names of the user agents, which wish to be informed for their updates.

14. Updating taxonomy directories • Each taxonomy directory has a different semantic classification. Because of that each directory requires different update approach and has its own update policies. • The PMO taxonomy directories must be updated only when a PMO enters or leaves from DBGlobe system. • The user profile may be updated more often either by user or by applications. • Finally the service taxonomy directories has to be updated whenever • the PMO that provides the service enters or leaves the DBGlobe system, • the service is updated or • a new service is available

15. PMO Ontology Directory User Ontology Directory Service Ontology Directory Implementation • We assume that the CASs will broadcast the ontologies profiles to the CoAS in order to build the communities. • Based to tha assumption we have implement an infrastructure of the basic components of DBGlobe system, CAS and PMOs that broadcast those information. • Additionaly in the CoAS side we have implement the following components • The PMO directory • The User directory • The service directory • The ontology Structure • We have build an infrastructure where PMOs,CoAS and CASs broadcasts their messages • Each message is captured in xml form. • In case of PMO it creates a xml message to register its self, to register a service or to register user profile. • The CAS filters messages filters messages that come from PMOs, and forwards them to the CoAS. • Finally CoAS filters those messages and if the message includes an ontology and the ontology belongs to the community, the CoAS will add this ontology to the tree. CAS Directory CoAS director

16. Status/Issues • Preparing a paper around this community concept • The deliverable D14 will be based on this paper • We are implement community middleware • In a class project we build two implementations on the basic CAS architecture • We used Bluetooth and the existing wireless LAN infrastructure, • We test the invocation of a web service by a mobile devices.

17. Integration with AXML and mobiShare • We assume that CASs broadcasts the ontologies schemas to the CoAS captured in xml format • We can create an interface to allow the searching of services by executing AXML queries.

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