MAGIK Architecture

Content:

• Overall Architecture
• 3 Layers
  • Interface Layer
  • Reasoning Layer
  • Data Layer
• Misc

Query Approximation

• Web interface: JavaServer Pages (JSP) that allow users to interact with the system. Related package: WebContent.
• JavaBeans: the Model component in Model-View-Controller (MVC) architecture, that connects View component (JSP) with Controller component (Java). Related package: it.unibz.inf.magik.beans.

• MAGIK business logic: the Controller component that process users input, run the reasoner (DLV engine), run the Prolog code using TuProlog, read/write to/from data layer (database), and return an output to users. Related package: it.unibz.inf.magik.web.
• Core: module which contains all related classes to encode TC-QC Java objects that is needed by DLV engine, and analyzes the returned answer set program by DLV engine. Also contains all related classes to encode schema, query and TC-statements for generating input file for the Prolog code that return the possible specializations of the query. Related packages: it.unibz.inf.magik.core, it.unibz.inf.magik.additional.

• Database connector: module to manage database connection, including read/write database schema & relation and evaluate SQL queries. Related package: it.unibz.inf.magik.db.
• Hibernate: module to accomodate Hibernate that provides the storage and retrieval of Java objects via Object/Relational Mapping. Related package: it.unibz.inf.magik.hibernate.

• DLV Wrapper: a Java library that wraps the DLV system inside an external application, allowing to embed disjunctive logic programs inside Object-Oriented source code.
• PostgreSQL JDBC Driver: a Java library that allows Java programs to connect to a PostgreSQL database using standard, database independent Java code.
• Exception handler: module to handle exceptions that may occur within the system. Related package: it.unibz.inf.magik.exception.
• Test: JUnit testing module to verify/validate the core classes. Related package: it.unibz.inf.magik.test.

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• index.jsp
• schema/
  • index.jsp that includes:
    • viewRelation.jsp
  • edit.jsp that includes:
    • showRelations.jsp
  • editConnection.jsp
  • editRelation.jsp
• constraints/
  • index.jsp that includes:
    • showFDC.jsp
    • showFK.jsp
    • showQuery.jsp
    • showTC.jsp
    • showQuerySuggestion.jsp
    • showTCSuggestion.jsp
  • editFK.jsp
  • editFDC.jsp
  • editTC.jsp
  • editQuery.jsp

Each JavaBeans class corresponds with the HTML form in the JavaServlet Pages.

• <fc blue>ShowSchemaBean</fc>, to get the selected schema to be processed (schema/index.jsp)
• <fc blue>EditSchemaBean</fc>, to get the schema name (schema/edit.jsp)
• <fc blue>EditRelationBean</fc>, to get the attributes of relation (schema/editRelation.jsp)
• <fc blue>EditConnectionBean</fc>, to get the information of database connection details (schema/editConnection.jsp)
• <fc blue>ShowContraintsBean</fc>, to get the selected constraints and query to be processed (constraints/index.jsp)
• <fc blue>EditForeignKeyBean</fc>, to get the attributes of foreign key (constraints/editFK.jsp)
• <fc blue>EditFiniteDomainBean</fc>, to get the attributes of finite domain constraint (constraints/editFDC.jsp)
• <fc blue>EditTCStatementBean</fc>, to get the attributes of TC statement (constraints/editTC.jsp)
• <fc blue>EditQueryBean</fc>, to get the attributes of query (constraints/editQuery.jsp)

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• SessionControl → Class for controlling the active session of the application, including process users input, run the reasoner (DLV engine), read/write to/from data layer (database), and return an output to users.
  • Read/write schemas from/to database : readDBSchemas, addDbConnection, addDbSchema
  • Write objects to database (via Hibernate) : hibernateSaveObject
  • Add/edit/delete schema : addSchema, updateSchema, deleteSchema
  • Add/edit/delete relation of the schema : addRelation, updateRelation, deleteRelation
  • Add/edit/delete foreign key of the schema : addForeignKey, updateForeignKey, deleteForeignKey
  • Add/edit/delete finite domain constraint : addFDC, updateFDC, deleteFDC
  • Add/edit/delete TC statement : addTCStatement, updateTCStatement, deleteTCStatement
  • Add/edit/delete query : addSQLQuery, updateSQLQuery, deleteQuery
  • Displaying information of query reasoning result : encodingProgram, printQueryResultHTML, isQueryComplete, approximateQuery
  • Import pre-defined sample schema : importSampleSchema
• SessionSchema extends Schema, with the information of selected foreign keys, finite domain constraints, and table completeness statements in the active session, also the information of database connection details (only for remote schema).

• Term → Class for term (variable or constant)
• Atom → Class for atom (array of terms)
• Query → Class for query that can be logically seen as a conjunction of relations.
• TC-Statement → Class for table completeness statement as it is defined by Razniewski&Nutt(VLDB2011).
• Schema → Class for SQL schema with a set of relations, over which over finite domain and foreign key constraints can be defined.
• Relation → Class for SQL relation defined with name, arity, and primary key definition.
• Foreign Key → Class for foreign key dependency between two relations from the common schema (sourceRelation[sourceAttr] → targetRelation[targetKey]).
• Finite Domain Constraints → Class for finite domain constraint defined over a single attribute in a relation.
• QueryGeneralization → Class for generating (if exists) the least specific specialization query of the given query. How it works
• QuerySpecialization → Class for generating (if exists) the most specific generalization query(ies) of the given query.
• ProgramGenerator → Class for translating the schema, constraints and query into DLV format
• <fc blue>ConjunctiveQuery</fc> → Class for traslating query into a conjunctive query.
• <fc blue>TCSuggestions</fc> → Class for suggested table completeness statements over a query so that the query will be complete.
• <fc blue>AuxiliaryFunctions</fc> → Class for auxiliary functions used by some java classes.
• <fc blue>CycleDetector</fc> → Class for detecting cycle inside foreign keys.
• <fc blue>DLV_Engine</fc> → Class for setting and running the DLV library.
• <fc blue>Preprocessor</fc> → Class for preprocessing the query in order to find (possibly) error or violations
• QueryMinimizer

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• DatabaseConnector → Class for database connection. Database connection is established with PostgreSQL JDBC Driver, a Java library that allows Java programs to connect to a PostgreSQL database.
  • Read schemas relations, and foreign keys from database : getSchemaType, getSchemas, getDbSchemas, getSchema, readRelation, readForeignKeys
  • Add/Edit/Delete schema (and relation) : addRelation, addSchema, deleteSchema, updateSchema
  • Get and add remote database connection information (only for remote database schema) : getDbUrl, getDbUser, getDbPassword, addDbConnection
  • Evaluate SQL query (only for remote database schema) : evaluateQuery
  • Validate and add user : validateUser, addUser
  • Initialize required tables in installation process (for localhost application version) : installation

• <fc blue>HibernateConnector</fc> → Class for Hibernate connection.
• <fc blue>MagikNamingStrategy</fc> → Class for custom naming strategy for table name in the database (in the format of <username_schemaName_tableName>), with provided username and schemaName, which is used to store objects.
• Configuration files:
  • FiniteDomainConstraint.hbm.xml → configuration file for storing finite domain constraints
  • ForeignKey.hbm.xml → configuration file for storing foreign keys
  • Query.hbm.xml → configuration file for storing queries
  • TCStatement.hbm.xml → configuration file for storing table completeness statements
  • hibernate.cfg.xml → configuration file for Hibernate connection

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• <fc blue>ContextException</fc> → Class for exception handler for adding/updating relation, foreign key, finite domain constraint, and table completeness statement.
• <fc blue>ParseSQLQueryException</fc> → Class for exception handler for SQL query parsing.
• <fc blue>CycleException</fc> → Class for exception handler for cycle detection.
• <fc blue>PrimaryKeyViolationException</fc> → Class for exception handler for primary key violation detection.

• <fc blue>AllTests</fc>
• <fc blue>CycleDetectionTest</fc>
• <fc blue>TestAtomClass</fc>
• <fc blue>TestDatabaseConnectorClass</fc>
• <fc blue>TestFK</fc>
• <fc blue>TestFK2</fc>
• <fc blue>TestHardCaseFDCandFK</fc>
• <fc blue>TestPreprocessor</fc>
• <fc blue>TestPrimaryViolation</fc>
• <fc blue>TestQueryClass</fc>
• <fc blue>TestQueryGeneralization</fc>
• <fc blue>TestQueryToSQL</fc>
• <fc blue>TestSimpleComparison</fc>
• <fc blue>TestTCQCReasonerBlackWhiteExample</fc>
• <fc blue>TestTCQCReasonerFKandFD</fc>
• <fc blue>TestTCQCReasonerPlainCompanyEx</fc>
• <fc blue>TestTCQCReasonerPlainSchoolEx</fc>
• <fc blue>TestTCQCReasonerTCSuggestions</fc>
• <fc blue>TestTCQCReasonerUnderFDC</fc>
• <fc blue>TestTermClass</fc>
• <fc blue>TestValQueryProblem.</fc>
• <fc blue>UnificationTest</fc>

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