Format

SEM_RDFCTX.ADD_DEPENDENT_POLICY(
     index_name     IN VARCHAR2, 
     policy_name    IN VARCHAR2, 
     partition_name IN VARCHAR2 DEFAULT NULL,
     network_owner  IN VARCHAR2 DEFAULT NULL,
     network_name   IN VARCHAR2 DEFAULT NULL);

Description

Adds a dependent policy to an (already created) index or index partition.

Parameters

index_name

Name of the index.

policy_name

Name of the dependent policy.

partition_name

If the specified index is local, the name of the target partition. (Otherwise, must be null.)

network_owner

Owner of the semantic network. (See Table 1-1.)

network_name

Name of the semantic network. (See Table 1-1.)

Usage Notes

The base policy corresponding to the new dependent policy must already be a part of the index.

For information about semantic network types and options, see Semantic Networks.

Examples

The following example adds a new dependent policy SEM_EXTR_PLUS_GEOONT to the index ArticleIndex.

begin
  sem_rdfctx.add_dependent_policy (index_name  => 'ArticleIndex',
                                   policy_name => 'SEM_EXTR_PLUS_GEOONT');
end;
/

Format

SEM_RDFCTX.CREATE_POLICY(
     policy_name   IN VARCHAR2, 
     extractor     IN mdsys.rdfctx_extractor, 
     preferences   IN sys.XMLType DEFAULT NULL,
     network_owner IN VARCHAR2 DEFAULT NULL,
     network_name  IN VARCHAR2 DEFAULT NULL);

or

SEM_RDFCTX.CREATE_POLICY(
     policy_name       IN VARCHAR2, 
     base_policy       IN VARCHAR2, 
     user_models       IN SEM_MODELS DEFAULT NULL, 
     user_entailments  IN SEM_MODELS DEFAULT NULL,
     network_owner     IN VARCHAR2 DEFAULT NULL,
     network_name      IN VARCHAR2 DEFAULT NULL);

Description

Creates an extractor policy. (The first format is for a base policy; the second format is for a policy that is dependent on a base policy.)

Parameters

policy_name

Name of the extractor policy.

extractor

An instance of a subtype of the RDFCTX_EXTRACTOR type that encapsulates the extraction logic for the information extractor.

preferences

Any preferences associated with the policy.

base_policy

Base extractor policy for a dependent policy.

user_models

List of user models for a dependent policy.

user_entailments

List of user entailments for a dependent policy.

network_owner

Owner of the semantic network. (See Table 1-1.)

network_name

Name of the semantic network. (See Table 1-1.)

Usage Notes

An extractor policy created using this procedure determines the characteristics of a semantic index that is created using the policy. Each extractor policy refers to an instance of an extractor type, either directly or indirectly. An extractor policy with a direct reference to an extractor type instance can be used to compose other extractor policies that include additional RDF models for ontologies.

An instance of the extractor type assigned to the extractor parameter must be an instance of a direct or indirect subtype of type mdsys.rdfctx_extractor.

The RDF models specified in the user_models parameter must be accessible to the user that is creating the policy.

The RDF entailments specified in the user_entailments parameter must be accessible to the user that is creating the policy. Note that the RDF models underlying the entailments do not get automatically included in the dependent policy. To include one or more of those underlying RDF models, you need to include the models in the user_models parameter.

The preferences specified for extractor policy determine the type of repository used for the documents to be indexed and other relevant information. For more information, see Indexing External Documents.

For information about semantic network types and options, see Semantic Networks.

Examples

The following example creates an extractor policy using the gatenlp_extractor extractor type, which is included with the Oracle Database support for semantic indexing.

begin
  sem_rdfctx.create_policy (policy_name => 'SEM_EXTR',
                            extractor   => mdsys.gatenlp_extractor());
end;
/

The following example creates a dependent policy for the previously created extractor policy, and it adds the user-defined RDF model geo_ontology to the dependent policy.

begin
  sem_rdfctx.create_policy (policy_name => 'SEM_EXTR_PLUS_GEOONT',
                            base_policy => 'SEM_EXTR',
                            user_models => SEM_MODELS ('geo_ontology'));
end;
/

Format

SEM_RDFCTX.DROP_POLICY(
     policy_name  IN VARCHAR2,
     network_owner IN VARCHAR2 DEFAULT NULL,
     network_name  IN VARCHAR2 DEFAULT NULL);

Description

Deletes (drops) an unused extractor policy.

Parameters

policy_name

Name of the extractor policy.

network_owner

Owner of the semantic network. (See Table 1-1.)

network_name

Name of the semantic network. (See Table 1-1.)

Usage Notes

An exception is generated if the specified policy being is used for a semantic index for documents or if a dependent extractor policy exists for the specified policy.

For information about semantic network types and options, see Semantic Networks.

Examples

The following example drops the SEM_EXTR_PLUS_GEOONT extractor policy.

begin
  sem_rdfctx.drop_policy (policy_name => 'SSEM_EXTR_PLUS_GEOONT');
end;
/

Format

SEM_RDFCTX.MAINTAIN_TRIPLES(
     index_name     IN VARCHAR2, 
     where_clause   IN VARCHAR2, 
     rdfxml_content IN sys.XMLType, 
     policy_name    IN VARCHAR2 DEFAULT NULL, 
     action         IN VARCHAR2 DEFAULT 'ADD',
     network_owner  IN VARCHAR2 DEFAULT NULL,
     network_name   IN VARCHAR2 DEFAULT NULL);

Description

Adds one or more triples to graphs that contain information extracted from specific documents.

Parameters

index_name

Name of the semantic index for documents.

where_clause

A SQL predicate (WHERE clause text without the WHERE keyword) on the table in which the documents are stored, to identify the rows for which to maintain the index.

rdfxml_content

Triples, in the form of an RDF/XML document, to be added to the individual graphs corresponding to the documents.

policy_name

Name of the extractor policy. If policy_name is null (the default), the triples are added to the information extracted by the default (or the only) extractor policy for the index; if you specify a policy name, the triples are added to the information extracted by that policy.

action

Type of maintenance operation to perform on the triples. The only value currently supported in ADD (the default), which adds the triples that are specified in the rdfxml_content parameter.

network_owner

Owner of the semantic network. (See Table 1-1.)

network_name

Name of the semantic network. (See Table 1-1.)

Usage Notes

The information extracted from the semantically indexed documents may be incomplete and lacking in proper context. This procedure enables a domain expect to add triples to individual graphs pertaining to specific semantically indexed documents, so that all subsequent SEM_CONTAINS queries can consider these triples in their document search criteria.

This procedure accepts the index name and WHERE clause text to identify the specific documents to be annotated with the additional triples. For example, the where_clause might be specified as a simple predicate involving numeric data, such as 'docId IN (1,2,3)'.

For information about semantic network types and options, see Semantic Networks.

Examples

The following example annotates a specific document with the semantic index ArticleIndex by adding triples to the corresponding individual graph.

begin
  sem_rdfctx.maintain_triples(
     index_name      => 'ArticleIndex',
     where_clause    => 'docid = 15',  
     rdfxml_content => sys.xmltype(
      '<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" 
                xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
                xmlns:pred="http://myorg.com/pred/">
       <rdf:Description rdf:about=" http://newscorp.com/Org/ExampleCorp">
         <pred:hasShortName 
               rdf:datatype="http://www.w3.org/2001/XMLSchema#string">
             Example
         </pred:hasShortName>
     </rdf:Description> 
    </rdf:RDF>'));
end;
/

Format

SEM_RDFCTX.SET_DEFAULT_POLICY(
     index_name    IN VARCHAR2, 
     policy_name   IN VARCHAR2,
     network_owner IN VARCHAR2 DEFAULT NULL,
     network_name  IN VARCHAR2 DEFAULT NULL);

Description

Sets the default extractor policy for a semantic index that is configured with multiple extractor policies.

Parameters

index_name

Name of the semantic index for documents.

policy_name

Name of the extractor policy to be used as the default extractor policy for the specified semantic index. Must be one of the extractor policies listed in the PARAMETERS clause of the CREATE INDEX statement that created index_name.

network_owner

Owner of the semantic network. (See Table 1-1.)

network_name

Name of the semantic network. (See Table 1-1.)

Usage Notes

When you create a semantic index for documents, you can specify multiple extractor policies as a space-separated list of names in the PARAMETERS clause of the CREATE INDEX statement. As explained in Semantically Indexing Documents, the first policy from this list is used as the default extractor policy for all SEM_CONTAINS queries that do not identify an extractor policy by name. You can use the SEM_RDFCTX.SET_DEFAULT_POLICY procedure to set a different default policy for the index.

For information about semantic network types and options, see Semantic Networks.

Examples

The following example sets CITY_EXTR as the default extractor policy for the ArticleIndex index.

begin
  sem_rdfctx.set_default_policy (index_name => 'ArticleIndex',
                                 policy_name => 'CITY_EXTR');
end;
/

Format

SEM_RDFCTX.SET_EXTRACTOR_PARAM(
     param_key     IN VARCHAR2, 
     patam_value   IN VARCHAR2, 
     param_desc    IN VARCHAR2,
     network_owner IN VARCHAR2 DEFAULT NULL,
     network_name  IN VARCHAR2 DEFAULT NULL);

Description

Configures the Oracle Database semantic indexing support to work with external information extractors, such as Calais and GATE.

Parameters

param_key

Key for the parameter to be set.

param_value

Value for the parameter to be set.

param_desc

Short description for the parameter to be set.

network_owner

Owner of the semantic network. (See Table 1-1.)

network_name

Name of the semantic network. (See Table 1-1.)

Usage Notes

To use this procedure, you must be connected as SYSTEM (not SYS … AS SYSDBA) or another non-SYS user with the DBA role.

To work with the Calais extractor type (see Configuring the Calais Extractor type), you must specify values for the following parameters:

• CALAIS_WS_ENDPOINT: Web service end point for Calais.

• CALAIS_KEY: License key for Calais.

• CALAIS_WS_SOAPACTION: SOAP action for the Calais Web service.

To work with the General Architecture for Text Engineering (GATE) extractor type (see Working with General Architecture for Text Engineering (GATE)), you must specify values for the following parameters:

• GATE_NLP_HOST: Host for the GATE NLP Listener.

• GATE_NLP_PORT: Port for the GATE NLP Listener.

In addition to these parameters, you may need to specify a value for the HTTP_PROXY parameter to work with information extractors or index documents that are outside the firewall.

A database instance only has one set of values for these parameters, and they are used for all instances of semantic indexes using the corresponding information extractor. You can use this procedure if you need to change the existing values of any of the parameters.

For information about semantic network types and options, see Semantic Networks.

Examples

For examples, see the following sections:

• Configuring the Calais Extractor type

• Working with General Architecture for Text Engineering (GATE)