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General Adaptation Framework. IOG. Contents. Adaptation in brief GAF overview Data Representation Standards Semantic Adaptation Adapter Software Design. Adaptation in brief. Adaptation as a general concept.
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Contents • Adaptation in brief • GAF overview • Data Representation Standards • Semantic Adaptation • Adapter Software Design
Adaptation as a general concept • There is a diversity of heterogeneous systems, applications, data formats and ways of interaction; • All those systems were tailored for particular tasks, purposes and goals; • The world is heterogeneous and we face the challenge trying to integrate heterogeneous systems into a unified environment; • The “Smart Resource” project has encountered exactly such kind of a problem.
General Adaptation • “General adaptation” assumes a design of a sufficient framework for an integration of different (by structure and nature) resources into Global Understanding eNvironment (GUN). • This environment will provide a mutual interaction between heterogeneous resources. • Adaptation assumes elaboration of a common mechanism for a new resource integration, and its provision with a unified way of interaction.
Adapter concept • The main idea of adaptation is based on a concept of “adapter”, which plays role of a bridge between an internal representation of resource and a unified environment. • Adapter is a software component, which provides a bidirectional link between a resource interface and an interface of the environment.
Adaptation of SmartResource • GUN assumes interoperability of SmartResources; • By Smart Resource we mean a conjunction of Real World Resource (RWR), Adapter and Agent; • By extending RWR within Adapter and Agent we make it GUN compatible; • General Adaptation includes development of Adapter for RWR.
GAF goals • We intend to design a common framework for adaptation of heterogeneous resources. • We assume dividing a design of the framework into two layers: • Structured software design for modules, classes, behavior and protocols; • Semantic adaptation of different formalizations of the industrial maintenance domain edges.
Processes in detail • Process Description Template: • Preconditions for process start • Process execution • Result
Family of Standards Arbitrary number of standards exist, which define each other on different levels of abstraction and thus form a hierarchy: Standard n define … Standard 2 define Standard 1 define Formal data representation
XML data representation Problems domain Problem domain XML Schema Specifications XML Schema XML Specifications XML document
Database Data Representation Problems domain Problem domain Relational Model SQL DDL Specification DB Schema DML Specification Content of DB
Semantic Data Representation Problems domain Problem domain OWL/RDFS Specifications RDF Schema/Ontology RDF Specifications RDF document
Arbitrary Data Representation Problem domain Problem domain Concrete Abstract Model Specification Domain specific model Data Representation Syntax Specification Domain specific data
Nested Models More abstract models define more specific ones. In different cases arbitrary number of models can be found in chains and layers Domain Domain … Domain Abstract Concrete … Model Specification Model Specification Domain specific model
Model2Model Adaptation Semantic Adaptation results in a mapping of data encoded according to one model to another model of data representation Model 1 Model 2 adaptation Encoded Data Encoded Data
Possible Formalization of Domain Problem domain DB Schema RDF Schema/Ontology XML Schema Content of DB RDF document XML document Relational model OWL/RDFS/RDF XML
Semantic Adaptation • During the data transformation process, Data Transformer involves format’s metadata (schemas) and transformation rules. • Schemas, rules and underlying ontologies constitute the semantic adaptation.
Semantic Adaptation tasks • Semantic Adaptation defines a functionality to work with semantics of: • Adapter Functionality (Services provided by the adapter) • Data representation standards and models of the adapted systems • Software interfaces standards of the adapted systems • Configuration properties of the adapter runtime environment • Semantic Adaptation uses an Ontology-based approach to define the semantics mentioned above: • This involves associating commonly understood meaning to the definition of adapter properties, functionality, configuration, and associated meta-data standards
Semantic Adaptation Stages • Analysis of problem domain and elaboration of a conceptual model; • Analysis of data representation formats; • Analysis of corresponding metadata (particular Database schema, for instance); • Analysis of a standard’s specification (e.g. XML Schema Specification standard); • Elaboration of the model for transformations of particular standards of data representation; • Specification of data mapping rules; • Choosing and/or Development of the mechanism or tool of transformation (appropriate patterns, APIs etc).
Semantic Adaptation Stages (Example) Conceptual model elaboration • Domain description: • Paper machine produces paper, uses cellulose … • Domain decomposition • Entities, classes, properties, relations, behavior … • Domain formalization • ER diagrams, UML, Ontology Description Decomposition Formalization
Semantic Adaptation Stages (Example) Analysis of data representation format • What data format is: • XML, text file, Excel table, Oracle data base… • What API could be used to process: • SQL queries, Java DOM API, XQquery… • Data’s access methods: • JDBC, OLE … • What standards are used to represent a format: • ASCII, W3C family standards … XML format Processed by Access by Standard XQuery Java API W3C family
Semantic Adaptation Stages (Example) Metadata analysis • What structure a schema has: • Elements, relationship, types… • Possible variations: • XML tags or values… • Hierarchy of elements and restrictions: • Nesting of classes, range… Analysis • SmartResource is subclass of Class • It has SmartMessage as ancestor • Range: enumeral types • <message title=“simple”></message> • or <message> • <title>simple</title> • </message>
Semantic Adaptation Stages (Example) Analysis of standard • What standard specification is: • Syntax, vendors, schema… • What formal theory exist: • Relational algebra, frame model… • What methods of transformation exist: • XSLT, productions rules… • Capabilities and restrictions: • Possibilities of formalization, querying … Analysis - Relational theory - SQL97 standard - Relational algebra (selection, projection, join) - transformable to object model, XML model
Semantic Adaptation Stages (Example) Model of transformation • What approaches of a transformation exist: • XSLT, piping… • What are the source/target resources: • XHTML to XML, Oracle DBMS to XML, • XML to RDF… • Possibility for further extension: • Costs of extension during evolution… • Role of metadata: • Schema integration, compatibility … B A C • - A can be transformed to C with XSLT • A is the XML file, C is an RDF file • A’s schema is dynamic • Schemas are interoperable
Semantic Adaptation Stages (Example) Data mapping rules • What is the protocol of transformation: • Elements and types matching… • What is rule’s format representation: • Ontology, XSLT… • Manual or semiautomatic matching Rules engine 1. Entity “Person ” correspond to tag <person> 2. Entity “Salary” corresponds to property “Income”
Semantic Adaptation Stages (Example) Mechanism of transformation • What possible approaches are there: • Tolls, APIs, Services… • What is the cost of particular approach: • Time for development, price of product… • Interoperability and extensibility of chosen approach: • Supported platforms, extensible API … - Shall we use ready tools or develop from scratch? - What API could be used in transformation? (XSLT, SAX, DOM)? - What functionality must be implemented (XML to RDF or more)?
How it could work One of the approach of adaptation is serializing RSCDF format into intermediate well standardized and elaborated format. As the basis, it’s intended to use XML format for this approach. Database RSCDF format in GUN XML XML IDE (Electronic Data Interchange) RSCDF transformation into particular standard HTML Possible solution: Design and development of unified mechanism of transformation RSCDF into XML format and vice versa
How it could work Design and development of transformation mechanism from RSCDF to XML format, which will allow to map schemas and data from RSCDF to XML. There are some projects which have elaborated pilot methods of transformation RDF to XML (http://w3future.com/xr/). Since RSCDF is enhanced subset of RDF it’s possible to adopt these methods. RDF model and XPath expressions RDF context XML context Set of XSLT style sheets The transformation is carried out by either replacements of XPATH expressions or by the set of XSLT style sheets
How it could work XML to other formats transformation Once the mechanism of transformation from RSCDF to XML and XML to RSCDF has been designed it’s possible to use standard approaches for future transformation Other formats XML XML XHTML RDBMS Choosing the XML format as the start point will allow to unify process of adaptation
How it could work Mapping XML to XML XML to XML transformation based upon two XML schemas. It’s also might be necessary to perform some processing functions to pipe data from source to target.
How it could work Mapping XML to relational model The process of mapping starts from the loading of database scheme and XML scheme. Then engineer manually fulfils matching between XML elements and database entities. While mapping it might be necessary to use processing functions.
Ontology 2 Ontology transformation • Ideal case: transformation Corresponds to world ontology World Ontology O 1 t O 2 t t t O 3 O n
Ontology 2 Ontology transformation • When all domain descriptions refer to common vocabulary (World ontology), mapping can be done explicitly • However incompleteness of one ontology may cause inability to transform in both directions
O 1 O 2 P2P ontology mapping • One ontology is mapped to other manually or in semi-automatic way • Mapping rules construction may meet following problems: • Different expert vision of problem domain • Models may be inconsistent conceptually • Paradigms the models are based on may cause hardly convertible schemas
Adapter to particular standard Formats and structures of data review: • Flat files (ASCII text files) • Tables (Excel) • Trees and taxonomies (xml, ontology-files) • Marked up structures (HTML) • Relational model (RDBMS) • Object model (Classes and objects) • Compound structure (any mixed specific structures)
Generic model mapping schema Model mapping tool (schema mapping) Model mapping tool (schema mapping) Model A Model B … Data transformation (reusable part) Data transformation (reusable part) Data … Target model Model mapping tool (schema mapping) Model N Data transformation (reusable part)
Model mapping tool (schema mapping) Document transformation (reusable part) Model mapping scheme Model mapping tool (schema mapping) XML Schema DB model … XML document Document/ content transformation (reusable part) DB content RscDF-schema … RscDF document Model mapping tool (schema mapping) … Data transformation (reusable part)
Document transformation RscDF 2 XML Schema mapping tool XML Schema 2 DB model mapping tool XML document DB … Document transformation (reusable part) Document transformation (reusable part) … RscDF-document Model mapping tool (schema mapping) … Document transformation (reusable part)
Existent Mapping tools • Existent tools: • RDBMS 2 XML Schema • XML 2 XML (XSLT) • RDF 2 XML • etc
Automation Problem Statement • It is evident that fully automated semantic adaptation cannot be implemented • The question is what level of automation is possible and how achieve it