org.licas.service.resource.container

Class QueryContainer

java.lang.Object

org.licas.service.resource.Resource

org.licas.service.resource.container.ResourceContainer

org.licas.service.resource.container.QueryContainer

public class QueryContainer
extends ResourceContainer

This can be used to store an array or set of Resource derived objects and return the details of any of them that match a query specification. To do this, the container uses a QueryDef derived query engine to evaluate the query expression, of type QueryMediator.

It uses the definition's executeQueryModel method on the contents of each resource. The query itself is sent as an XML-script that is a parsed version of the licas_text package QueryModel. You can use the related QueryParser to parse to or from XML.

Alternatively, you can write your own query engine, that implements QueryDef, pass the class name as part of the constructor script Value element and it will be created instead. If you then add your own parser for a new query model, or still use the existing one, you can perform your own evaluations.

Author:

Kieran Greer

Field Summary

Fields inherited from class org.licas.service.resource.container.ResourceContainer

resourceList

Fields inherited from class org.licas.service.resource.Resource

dataType, INFOANYTYPE, INFOBINARYTYPE, INFOHTMLTYPE, INFOSTREAMXMLTYPE, INFOSTRINGTYPE, INFOTEXTTYPE, INFOURLTYPE, INFOXMLTYPE, LISTCONTAINERTYPE, QUERYCONTAINERTYPE, RANDOMCONTAINERTYPE, uuid

Constructor Summary

Constructors

Constructor and Description
QueryContainer(java.lang.String theDataType) Create a new instance of QueryContainer.
QueryContainer(java.lang.String theDataType, org.licas_xml.abs.Element dataXml) Create a new instance of QueryContainer.

Method Summary

Modifier and Type	Method and Description
org.licas_xml.abs.Element	getInfo(org.licas_xml.abs.Element infoDescr) Get the source information wrapped in an XML element.
java.lang.Object	getValue(org.licas_xml.abs.Element infoDescr) Get the currently selected value itself and not a wrapped description.
protected boolean	parseInfo(org.licas_xml.abs.Element dataXml) Parse the data description in the admin document to create the data object.

Methods inherited from class org.licas.service.resource.container.ResourceContainer

addResource, createContainer, getResource, getResourceIDs, removeResource

Methods inherited from class org.licas.service.resource.Resource

createResource, dataFromResourceType, getDataType, getUUID, parseValueElem, resourceTypeForDataType, setUUID, setUUID

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

QueryContainer

public QueryContainer(java.lang.String theDataType)
               throws java.lang.Exception

Create a new instance of QueryContainer.

Parameters:

theDataType - the container type.

Throws:

java.lang.Exception - any error.

QueryContainer

public QueryContainer(java.lang.String theDataType,
                      org.licas_xml.abs.Element dataXml)
               throws java.lang.Exception

Create a new instance of QueryContainer.

Parameters:

theDataType - the container type.

dataXml - a description of the initialisation parameters.

Throws:

java.lang.Exception - any error.

Method Detail

parseInfo

protected boolean parseInfo(org.licas_xml.abs.Element dataXml)
                     throws java.lang.Exception

Parse the data description in the admin document to create the data object.

Overrides:

parseInfo in class ResourceContainer

Parameters:

dataXml - the Data element of the admin document. This should include the container DataType element and a Value element that stores a list of child Data elements that store information for each resource to create. The Value element can also optionally store a different query engine type. This would be the class name and is assumed to be from a local jar file. It would be stored in another Value element that could be created using MetaFactory.addXML(adminData, (MetaFactory.createMetaValueXML(Const.VALUE, query-engine-class), Const.VALUE), for example.

Returns:

true if any specified resources are successfully added, false otherwise.

Throws:

java.lang.Exception - any error.

getInfo

public org.licas_xml.abs.Element getInfo(org.licas_xml.abs.Element infoDescr)
                                  throws java.lang.Exception

Get the source information wrapped in an XML element.

Specified by:

getInfo in class Resource

Parameters:

infoDescr - a description of the query to execute on each resource. The QueryModel is used as default.

Returns:

the query reply value.

Throws:

java.lang.Exception - any error.

getValue

public java.lang.Object getValue(org.licas_xml.abs.Element infoDescr)
                          throws java.lang.Exception

Get the currently selected value itself and not a wrapped description. For a query container, this is in fact the same operation as getInfo and returns the same query reply Element.

Specified by:

getValue in class Resource

Parameters:

infoDescr - a description of the query to execute on the resources. The QueryModel is used as default.

Returns:

the query reply value.

Throws:

java.lang.Exception - any error.