QueryMediator
Keywords: uk.ac.ic.doc.rodex.qproc.QueryMediator class

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## uk.ac.ic.doc.rodex.qproc
Class QueryMediator

    java.lang.Object
      uk.ac.ic.doc.rodex.qproc.QueryMediator

All Implemented Interfaces:
  IQueryMediator

    public class QueryMediator

extends java.lang.Object
implements IQueryMediator

QueryMediator.java This class is the interface to the query processing and execution engine. Its job is to cordinate different components to execute user queries (local and P2P)

Author:
  Duc M Le dmle@doc.ic.ac.uk Created on April 5, 2006 Department of Computing, Imperial College

Field Summary
`static int` | `LANG_STANDARD`
`static int` | `LANG_XQUERY`

Method Summary
`java.lang.String` | `getDebugInf()` Debug information
`java.lang.String` | `getDebugResult()` Debug result
`java.lang.String` | `getExternalQuery()` Getter methods for various query (`ASG`) objects
`java.lang.String` | `getFormulatedQuery()`
`java.lang.String` | `getLogicalOptimisedQuery()`
`static QueryMediator` | `getMediatorInstance()` Create a singleton mediator object
`java.lang.String` | `getPhysicalOptimisedQuery()`
`java.lang.String` | `getProcessedQuery()`
`void` | `getSODefinition(QuerySubGoal qsg)` Get query definitions for a schema object.
`java.util.List` | `performQuery(QueryDescription qd, Schema srcSchema, Schema[] targetSchemas)` Overloading method to perform a query given only the name of the public schema
`java.util.List` | `performQuery(QueryDescription qd, java.lang.String schemaName)`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### LANG_STANDARD

    public static final int LANG_STANDARD

See Also:
  Constant Field Values

### LANG_XQUERY

    public static final int LANG_XQUERY

See Also:
  Constant Field Values

Method Detail

### getMediatorInstance

    public static QueryMediator getMediatorInstance()

  Create a singleton mediator object

### performQuery

    public java.util.List performQuery(QueryDescription qd,
                                       java.lang.String schemaName)
                                throws QueryProcessingException,
                                       AutoMedException

  Throws:
    `QueryProcessingException`
    `AutoMedException`

### performQuery

    public java.util.List performQuery(QueryDescription qd,
                                       Schema srcSchema,
                                       Schema[] targetSchemas)
                                throws QueryProcessingException,
                                       AutoMedException

  Overloading method to perform a query given only the name of the public schema

  Parameters:
    `qd` - the `QueryDescription` object
    `useCache` - boolean value to indicate whether or not to use cache for rewriting
    `optimisedQuery` - boolean value to optimise query or not
    `rewriteQuery` - boolean value to rewrite query or not
    `lang` - query language type used
    `srcSchema` - the `Schema` upon which the query is posted
    `targetSchemas` - an array of data-source `Schema`s to which query is actually sent for execution. Note that targetSchemas is a subset of the actual data sources of srcSchema
  Returns:
    List the query result
  Throws:
    `QueryProcessingException`
    `AutoMedException`

### getSODefinition

    public void getSODefinition(QuerySubGoal qsg)
                         throws IntegrityException,
                                DataSourceException

  Get query definitions for a schema object. This method basically extracts the schema from the qsg argument, retrieves the associated `Schema` object, retrieves the associated `AutoMedWrapper` object to this schema and invoke the `AutoMedWrapper.getSODefinition()` method to do do the job

  Throws:
    `IntegrityException`
    `DataSourceException`

### getExternalQuery

    public java.lang.String getExternalQuery()

  Getter methods for various query (`ASG`) objects

### getFormulatedQuery

    public java.lang.String getFormulatedQuery()

### getProcessedQuery

    public java.lang.String getProcessedQuery()

### getLogicalOptimisedQuery

    public java.lang.String getLogicalOptimisedQuery()

### getPhysicalOptimisedQuery

    public java.lang.String getPhysicalOptimisedQuery()

### getDebugInf

    public java.lang.String getDebugInf()

  Debug information

### getDebugResult

    public java.lang.String getDebugResult()

  Debug result

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