ExistClient

Introduction

The ExistClient is a Java library that implements the ISClient interface provided by the gCoreFramework. This library allows the developer to execute queries on the Information System. This ExistClient implementation reduces possible range of queries (statically implemented), each of them has a template as more generic as possible. This has been thought for covering all the main cases, enabling the user to create dinamically the query as he/she likes better enriching the query with the parameters he/she needs. There are three kinds of queries to execute on the IS: GCUBEResourceQuery, WSResourceQuery and GCUBEGenericQuery.

Implementation Overview

The ExistClient implements all the queries defined in the ISClient Interface:

Queries over GCUBEResource:

• GCUBECollectionQuery
• GCUBECSInstanceQuery
• GCUBECSQuery
• GCUBEExternalRIQuery
• GCUBEGenericResourceQuery
• GCUBEGHNQuery
• GCUBEMCollectionQuery
• GCUBERIQuery
• GCUBEServiceQuery
• GCUBETPQuery
• GCUBEVREQuery

This queries returns a List of specialized GCUBEResource.

Queries over GCUBEWSResource:

• WSResourceQuery

This query returns a List of RPDocument. The RPDocument object allows developer to retrieve the informations on WSResourceProperties or to exceute XPath .

The ExistClient also offers the possibility to execute custom queries: GCUBEGenericQuery. GCUBEGenericQuery allows the developer to set the query expression to execute and to use a predefined set of queries which he should set some parameters on listed below:

• GCUBEResourceQuery:
  • TYPE
  • FILTER
  • RESULT (the default value returns Ids)
• GCUBEWSResourceQuery:
  • FILTER
  • RESULT (the default value is the entire Properties Document Data)
• RIEndpoint:
  • NAME (Service name)
  • CLASS (Service class)
  • ENTRY (the entry point)
• RIOnGHN:
  • ID (the GHN id)
• RISpecificData:
  • NAME (Service name)
  • CLASS (Service class)
  • ENTRY (the entry point)
• GHNIDFromHostName:
  • NAME (GHN name)
  • RESULT (the default value returns Ids)
• InternalCollections
• InternalCollectionIDs
• UserCollectionIDsFromSchemaURI
  • URI (the schema uri)
• MCollectionIDForCollection
  • ID (related collection ID)
• MCollectionFormatsForCollection
  • ID (related collection ID)
• MCollectionIDFromCollectionIDAndRole
  • ID (related collection ID)
  • ROLE (secondary role)
• MCollectionIDFromMFLanguage
  • LANGUAGE (metadata format language)
• MCollectionIDFromName
  • NAME (metadata collection name)
• MCollectionIDFromSchemaURI
  • URI (schema uri)

This kind of queries returns a List of XMLResult. The XMLResult object allows the developer to explore the contained document with XPaths.

Usage Examples

Query over GCUBEResource examples:

GCUBERIQuery RIquery = client.getQuery(GCUBERIQuery.class);
RIquery.addAtomicConditions(new AtomicCondition("//Endpoint@EntryName","gcube/annotationmanagement/abe/factory"),new AtomicCondition("//ServiceName","ABE"));
for (GCUBERunningInstance instance : client.execute(RIquery,GCUBEScope.getScope("/gcube/devsec")))
logger.debug(instance.getServiceName()+"("+instance.getID()+")");

GCUBEGHNQuery GHNquery = client.getQuery(GCUBEGHNQuery.class);
for (GCUBEHostingNode node : client.execute(GHNquery,GCUBEScope.getScope("/gcube/devsec"))) l
logger.debug(node.getID()+"("+node.getNodeDescription().getName()+")");

GCUBERIQuery RIquery = client.getQuery(GCUBERIQuery.class);
RIquery.addGenericCondition("$result/Profile/ServiceName/string() eq 'GHNManager' or $result/Profile/ServiceName/string() eq 'SoftwareRepository'");
for (GCUBERunningInstance instance : client.execute(RIquery,GCUBEScope.getScope("/gcube/devsec")))
                      logger.debug(instance.getServiceName()+"("+instance.getID()+")");

Query over WSResource examples:

WSResourceQuery wsquery = client.getQuery(WSResourceQuery.class);
wsquery.addAtomicConditions(new AtomicCondition("//ServiceClass","Samples"));
for (RPDocument d : client.execute(wsquery,GCUBEScope.getScope("/gcube/devsec"))) 
logger.(d.getEndpoint()+":+d.getVO()+":"d.evaluate("//MyRP").get(0));

GCUBEGenericQuery example:

GCUBEGenericQuery query = client.getQuery(GCUBEGenericQuery.class);
query.setExpression("for $Profile in collection(\"/db/Profiles\")//Document/Data/child::*[local-name()='Profile']/Resource return $Profile/UniqueID");
List<XMLResult> result =client.execute(query, scope);
for (String resultItem :result ) {
logger.debug(resultItem.evaluate("an XPath ... ")); 
logger.debug(resultItem.toString());
}

Predefined generic query examples:

GCUBEGenericQuery query = client.getQuery("GCUBEResourceQuery");
for (XMLResult result : client.execute(query,scope)) logger.debug(result.evaluate("/ID/text()"));//displays a singleton list
//a bit of customisation goes a long way whilst keeping the previous abstractions
query.addParameters(new QueryParameter("RESULT","$result/Type"));
for (XMLResult result : client.execute(query, scope)) logger.debug(result.evaluate("/Type/text()"));

//specialise to GCUBE Running Instances (NB. queries can be composed incrementally, possibly by different objects in different methods)
query.addParameters(new QueryParameter("TYPE",GCUBERunningInstance.TYPE)); 
for (XMLResult result : client.execute(query,scope)) logger.debug(result.evaluate("/Type/text()"));
//introduce a filter (NB. parameters can be added in batches) 
query.addParameters(new QueryParameter("TYPE",GCUBERunningInstance.TYPE), //ovverride previous setting
     new QueryParameter("FILTER","$result/Profile/ServiceClass/string() eq 'Annotation'"),
     new QueryParameter ("RESULT", "$result/Profile/Description")); //any Xquery condition on $result would do
for (XMLResult result : client.execute(query,scope)) logger.debug(result.evaluate("//Description")); //displays a singleton list