7 Jena Adapter for Oracle Database

7.2.1 Creating the Required Data Source Using WebLogic Server

If you need help creating the required J2EE data source using the WebLogic Server admin console, you can follow these steps:

1. Login to: http://<hostname>:7001/console

2. In the Domain Structure panel, click Services.

3. Click JDBC

4. Click Data Services.

5. In the Summary of JDBC Data Sources panel, click New under the Data Sources table.

6. In the Create a New JDBC Data Source panel, enter or select the following values.

   Name: OracleSemDS

   JNDI Name: OracleSemDS

   Database Type: Oracle

   Database Driver: Oracle's Driver (Thin) Versions: 9.0.1,9.2.0,10,11

7. Click Next twice.

8. In the Connection Properties panel, enter the appropriate values for the Database Name, Host Name, Port, Database User Name (schema that contains semantic data), Password fields.

9. Click Next.

10. Select (check) the target server or servers to which you want to deploy this OracleSemDS data source.

11. Click Finish.

    You should see a message that all changes have been activated and no restart is necessary.

7.2.2 Configuring the SPARQL Service

By default, the SPARQL Service endpoint assumes that the queries are to be executed against a semantic model with a pre-set name. This semantic model is owned by the schema specified in the J2EE data source with JNDI name OracleSemDS. Note that you do not need to create this model explicitly using PL/SQL or Java; if the model does not exist in the network, it will be automatically created, along with the necessary application table and index.

However, you must configure the SPARQL service by editing the joseki-config.ttl configuration file, which is in <domain_name>/autodeploy/joseki.war.

The supplied joseki-config.ttl file includes a section similar to the following for the Oracle data set:

#
## Datasets
#
[] ja:loadClass "oracle.spatial.rdf.client.jena.assembler.OracleAssemblerVocab" .
 
oracle:Dataset  rdfs:subClassOf  ja:RDFDataset .
 
<#oracle> rdf:type oracle:Dataset;
    joseki:poolSize     1 ;         ## Number of concurrent connections allowed to this dataset.
    oracle:connection
    [ a oracle:OracleConnection ;
    ];
    oracle:defaultModel [ oracle:firstModel "TEST_MODEL" ] .

In this section of the file, you can:

• Modify the joseki:poolSize value, which specifies the number of concurrent connections allowed to this Oracle data set (<#oracle> rdf:type oracle:Dataset;), which points to various RDF models in the database.

• Modify the name (or the object value of oracle:firstModel predicate) of the defaultModel, to use a different semantic model for queries. You can also specify multiple models, and one or more rulebases for this defaultModel.

  For example, the following specifies two models (named ABOX and TBOX) and an OWLPRIME rulebase for the default model. Note that models specified using the oracle:modelName predicate must exist; they will not be created automatically.

  <#oracle> rdf:type oracle:Dataset;
      joseki:poolSize     1 ;         ## Number of concurrent connections allowed to this dataset.
      oracle:connection
      [ a oracle:OracleConnection ;
      ];
      oracle:defaultModel [ oracle:firstModel "ABOX";
                                        oracle:modelName "TBOX";
                                        oracle:rulebaseName "OWLPRIME" ] .
  

• Use a virtual model for queries by adding oracle:useVM "TRUE", as shown in the following example. Note that if the specified virtual model does not exist, it will automatically be created on demand.

  <#oracle> rdf:type oracle:Dataset;
      joseki:poolSize     1 ;         ## Number of concurrent connections allowed to this dataset.
      oracle:connection
      [ a oracle:OracleConnection ;
      ];
      oracle:defaultModel [ oracle:firstModel "ABOX";
                                       oracle:modelName "TBOX";
                                       oracle:rulebaseName "OWLPRIME";
                                       oracle:useVM "TRUE"
      ] .
  

  For more information, see Section 7.8.1, "Virtual Models Support".

• Set the queryOptions and inferenceMaintenance properties to change the query behavior and inference update mode. (See the Javadoc for information about QueryOptions and InferenceMaintenanceMode.)

  By default, QueryOptions.ALLOW_QUERY_INVALID_AND_DUP and InferenceMaintenanceMode.NO_UPDATE are set, for maximum query flexibility and efficiency.

-Doracle.spatial.rdf.client.jena.clientIdentifier=<identificationString>

SQL> EXECUTE DBMS_MONITOR.CLIENT_ID_TRACE_ENABLE('JenaAdapter', true, true);

7.2.3 Terminating Long-Running SPARQL Queries

Because some applications need to be able to terminate long-running SPARQL queries, an abort framework has been introduced with the Jena Adapter and the Joseki setup. Basically, for queries that may take a long time to run, you must stamp each with a unique query ID (qid) value.

For example, the following SPARQL query selects out the subject of all triples. A query ID (qid) is set so that this query can be terminated upon request.

PREFIX ORACLE_SEM_FS_NS:  <http://example.com/semtech#qid=8761>
SELECT ?subject WHERE {?subject ?property ?object }

The qid attribute value is of long integer type. You can choose a value for the qid for a particular query based on your own application needs.

To terminate a SPARQL query that has been submitted with a qid value, applications can send an abort request to a servlet in the following format and specify a matching QID value

http://<hostname>:7001/joseki/querymgt?abortqid=8761

7.2.4 N-Triples Encoding for Non-ASCII Characters

For any non-ASCII characters in the lexical representation of RDF resources, \uHHHH N-Triples encoding is used when the characters are inserted into the Oracle database. (For details about N-Triples encoding, see http://www.w3.org/TR/rdf-testcases/#ntrip_grammar.) Encoding of the constant resources in a SPARQL query is handled in a similar fashion.

Using \uHHHH N-Triples encoding enables support for international characters, such as a mix of Norwegian and Swedish characters, in the Oracle database even if a supported Unicode character set is not being used.

7.5.1 Compilation of SPARQL queries to a single SEM_MATCH Call

SPARQL queries involving DISTINCT, OPTIONAL, FILTER, UNION, ORDER BY, and LIMIT are converted to a single Oracle SEM_MATCH table function. If a query cannot be converted directly to SEM_MATCH because it uses SPARQL features not supported by SEM_MATCH (for example, CONSTRUCT), the Jena Adapter employs a hybrid approach and tries to execute the largest portion of the query using a single SEM_MATCH function while executing the rest using the Jena ARQ query engine.

For example, the following SPARQL query is directly translated to a single SEM_MATCH table function:

PREFIX dc:  <http://purl.org/dc/elements/1.1/> 
PREFIX rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#> 
PREFIX foaf: <http://xmlns.com/foaf/0.1/> 
SELECT ?person ?name 
  WHERE {
                 {?alice foaf:knows ?person . }
               UNION { 
                 ?person ?p ?name. OPTIONAL { ?person ?x ?name1 } 
                     }
        }

However, the following example query is not directly translatable to a single SEM_MATCH table function because of the CONSTRUCT keyword:

PREFIX vcard: <http://www.w3.org/2001/vcard-rdf/3.0#> 
CONSTRUCT  { <http://example.org/person#Alice> vcard:FN ?obj } 
  WHERE  { { ?x <http://pred/a> ?obj.}
         UNION
         { ?x <http://pred/b> ?obj.}  }

In this case, the Jena Adapter converts the inner UNION query into a single SEM_MATCH table function, and then passes on the result set to the Jena ARQ query engine for further evaluation.

7.5.2 Optimized Handling of Property Paths

As defined in Jena, a property path is a possible route through an RDF graph between two graph nodes. Property paths are an extension of SPARQL and are more expressive than basic graph pattern queries, because regular expressions can be used over properties for pattern matching RDF graphs. For more information about property paths, see the documentation for the Jena ARQ query engine.

The Jena Adapter supports all Jena property path types through the integration with the Jena ARQ query engine, but it converts some common path types directly to native SQL hierarchical queries (not based on SEM_MATCH) to improve performance. The following types of property paths are directly converted to SQL by the Jena Adapter:

• Predicate alternatives: (p1 | p2 | … | pn) where pi is a property URI

• Predicate sequences: (p1 / p2 / … / pn) where pi is a property URI

• Reverse paths : ( ^ p ) where p is a predicate URI

• Complex paths: p+, p*, p{0, n} where p could be an alternative, sequence, reverse path, or property URI

Path expressions that cannot be captured in this grammar are not translated directly to SQL by the Jena Adapter, and they are answered using the Jena query engine.

The following example contains a code snippet using a property path expression with path sequences:

String m = "PROP_PATH";
 
ModelOracleSem model = ModelOracleSem.createOracleSemModel(oracle, m);
 
GraphOracleSem graph = new GraphOracleSem(oracle, m);    
    
// populate the RDF Graph
    graph.add(Triple.create(Node.createURI("http://a"),
    Node.createURI("http://p1"),
    Node.createURI("http://b")));
 
graph.add(Triple.create(Node.createURI("http://b"),
 Node.createURI("http://p2"),
 Node.createURI("http://c")));
 
graph.add(Triple.create(Node.createURI("http://c"),
 Node.createURI("http://p5"),
 Node.createURI("http://d")));
 
String query =
" SELECT ?s  " +
" WHERE {?s (<http://p1>/<http://p2>/<http://p5>)+ <http://d>.}";
   
QueryExecution qexec = 
      QueryExecutionFactory.create(QueryFactory.create(query, 
 Syntax.syntaxARQ), model);
 
try {
  ResultSet results = qexec.execSelect();
  ResultSetFormatter.out(System.out, results);
}
finally {
  if (qexec != null)
    qexec.close();
}
     
OracleUtils.dropSemanticModel(oracle, m);
model.close();

7.5.3 Optimized Handling of Plain BGP and OPTIONAL Queries

The Jena Adapter automatically translates basic graph pattern (BGP) and parallel OPTIONAL queries directly to native SQL (not based on SEM_MATCH). The advantage of this approach is that you can specify directives such as RESULT_CACHE in the query to improve performance.

The following queries are translated directly to SQL:

• Plain BGP queries. For example:

  SELECT ?x ?y WHERE {?x urn:a ?o. ?o ?p ?y}
  

• Queries using parallel OPTIONAL clauses. For example:

  SELECT ?x ?y      
  WHERE {?x urn:a ?o. 
         OPTIONAL {?x urn:b ?b} 
         OPTIONAL {?x urn:c ?c} }
  

• Queries using property paths (see Section 7.5.2, "Optimized Handling of Property Paths"). For example:

  SELECT ?x ?y  
  WHERE {?x urn:a ?o. OPTIONAL {?x urn:b* ?b} }
  

7.6.1 SQL Hints

SQL hints can be passed to a SEM_MATCH query including a line in the following form:

PREFIX ORACLE_SEM_HT_NS: <http://oracle.com/semtech#hint>

Where hint can be any hint supported by SEM_MATCH. For example:

PREFIX ORACLE_SEM_HT_NS: <http://oracle.com/semtech#leading(t0,t1)> 
SELECT ?book ?title ?isbn     
WHERE { ?book <http://title> ?title. ?book <http://ISBN> ?isbn }

In this example, t0,t1 refers to the first and second patterns in the query.

Note the slight difference in specifying hints when compared to SEM_MATCH. Due to restrictions of namespace value syntax, a comma (,) must be used to separate t0 and t1 (or other hint components) instead of a space.

For more information about using SQL hints, see Section 1.6, "Using the SEM_MATCH Table Function to Query Semantic Data", specifically the material about the HINT0 keyword in the options attribute.

7.6.2 Using Bind Variables in SPARQL Queries

In Oracle Database, using bind variables can reduce query parsing time and increase query efficiency and concurrency. Bind variable support in SPARQL queries is provided through namespace pragma specifications similar to ORACLE_SEM_FS_NS.

Consider a case where an application runs two SPARQL queries, where the second (Query 2) depends on the partial or complete results of the first (Query 1). Some approaches that do not involve bind variables include:

• Iterating through results of Query 1 and generating a set of queries. (However, this approach requires as many queries as the number of results of Query 1.)

• Constructing a SPARQL filter expression based on results of Query 1.

• Treating Query 1 as a subquery.

Another approach in this case is to use bind variables, as in the following sample scenario:

Query 1:
 
  SELECT ?x
    WHERE { ... <some complex query> ... };
 
 
Query 2:
 
  SELECT ?subject ?x
    WHERE {?subject <urn:related> ?x .};

The following example shows Query 2 with the syntax for using bind variables with the Jena Adapter:

PREFIX ORACLE_SEM_FS_NS: <http://oracle.com/semtech#no_fall_back,s2s>
PREFIX ORACLE_SEM_UEAP_NS: <http://oracle.com/semtech#x$RDFVID%20in(?,?,?)>
PREFIX ORACLE_SEM_UEPJ_NS: <http://oracle.com/semtech#x$RDFVID>
PREFIX ORACLE_SEM_UEBV_NS: <http://oracle.com/semtech#1,2,3>
SELECT ?subject ?x
WHERE {
  ?subject <urn:related>  ?x
};

This syntax includes using the following namespaces:

• ORACLE_SEM_UEAP_NS is like ORACLE_SEM_AP_NS, but the value portion of ORACLE_SEM_UEAP_NS is URL Encoded. Before the value portion is used, it must be URL decoded, and then it will be treated as an additional predicate to the SPARQL query.

  In this example, after URL decoding, the value portion (following the # character) of this ORACLE_SEM_UEAP_NS prefix becomes "x$RDFVID in(?,?,?)". The three question marks imply a binding to three values coming from Query 1.

• ORACLE_SEM_UEPJ_NS specifies the additional projections involved. In this case, because ORACLE_SEM_UEAP_NS references the x$RDFVID column, which does not appear in the SELECT clause of the query, it must be specified. Multiple projections are separated by commas.

• ORACLE_SEM_UEBV_NS specifies the list of bind values that are URL encoded first, and then concatenated and delimited by commas.

Conceptually, the preceding example query is equivalent to the following non-SPARQL syntax query, in which 1, 2, and 3 are treated as bind values:

SELECT ?subject ?x
  WHERE {
    ?subject <urn:related>  ?x
  }
  AND ?x$RDFVID in (1,2,3);

In the preceding SPARQL example of Query 2, the three integers 1, 2, and 3 come from Query 1. You can use the oext:build-uri-for-id function to generate such internal integer IDs for RDF resources. The following example gets the internal integer IDs from Query 1:

PREFIX oext: <http://oracle.com/semtech/jena-adaptor/ext/function#>
SELECT ?x  (oext:build-uri-for-id(?x) as ?xid)
WHERE { ... <some complex query> ... };

The values of ?xid have the form of <rdfvid:integer-value>. The application can strip out the angle brackets and the "rdfvid:" strings to get the integer values and pass them to Query 2.

Consider another case, with a single query structure but potentially many different constants. For example, the following SPARQL query finds the hobby for each user who has a hobby and who logs in to an application. Obviously, different users will provide different <uri> values to this SPARQL query, because users of the application are represented using different URIs.

SELECT ?hobby
  WHERE { <uri> <urn:hasHobby> ?hobby };

One approach, which would not use bind variables, is to generate a different SPARQL query for each different <uri> value. For example, user Jane Doe might trigger the execution of the following SPARQL query:

SELECT ?hobby WHERE {
<http://www.example.com/Jane_Doe> <urn:hasHobby> ?hobby };

However, another approach is to use bind variables, as in the following example specifying user Jane Doe:

PREFIX ORACLE_SEM_FS_NS: <http://oracle.com/semtech#no_fall_back,s2s>
PREFIX ORACLE_SEM_UEAP_NS: <http://oracle.com/semtech#subject$RDFVID%20in(ORACLE_ORARDF_RES2VID(?))>
PREFIX ORACLE_SEM_UEPJ_NS: <http://oracle.com/semtech#subject$RDFVID>
PREFIX ORACLE_SEM_UEBV_NS: <http://oracle.com/semtech#http%3a%2f%2fwww.example.com%2fJohn_Doe>
SELECT ?subject ?hobby
  WHERE {
    ?subject <urn:hasHobby>  ?hobby
  };

Conceptually, the preceding example query is equivalent to the following non-SPARQL syntax query, in which http://www.example.com/Jane_Doe is treated as a bind variable:

SELECT ?subject ?hobby
WHERE {
  ?subject <urn:hasHobby>  ?hobby
}
AND ?subject$RDFVID in (ORACLE_ORARDF_RES2VID('http://www.example.com/Jane_Doe'));

In this example, ORACLE_ORARDF_RES2VID is a function that translates URIs and literals into their internal integer ID representation. This function is created automatically when the Jena Adapter is used to connect to an Oracle database.

7.6.3 Additional WHERE Clause Predicates

The SEM_MATCH filter attribute can specify additional selection criteria as a string in the form of a WHERE clause without the WHERE keyword. Additional WHERE clause predicates can be passed to a SEM_MATCH query including a line in the following form:

PREFIX ORACLE_SEM_AP_NS: <http://oracle.com/semtech#pred>

Where pred reflects the WHERE clause content to be appended to the query. For example:

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX ORACLE_SEM_AP_NS:<http://www.oracle.com/semtech#label$RDFLANG='fr'>  
SELECT DISTINCT ?inst ?label
  WHERE { ?inst a <http://someCLass>. ?inst rdfs:label ?label . }
  ORDER BY (?label) LIMIT 20

In this example, a restriction is added to the query that the language type of the label variable must be 'fr'.

7.6.4 Additional Query Options

Additional query options can be passed to a SEM_MATCH query including a line in the following form:

PREFIX ORACLE_SEM_FS_NS: <http://oracle.com/semtech#option>

Where option reflects a query option (or multiple query options delimited by commas) to be appended to the query. For example:

PREFIX ORACLE_SEM_FS_NS:   
<http://oracle.com/semtech#timeout=3,dop=4,INF_ONLY,ORDERED,ALLOW_DUP=T>
SELECT * WHERE {?subject ?property ?object }

The following query options are supported:

• ALLOW_DUP=t chooses a faster way to query multiple semantic models, although duplicate results may occur.

• BEST_EFFORT_QUERY=t, when used with the TIMEOUT=n option, returns all matches found in n seconds for the SPARQL query.

• DEGREE=n specifies, at the statement level, the degree of parallelism (n) for the query. With multi-core or multi-CPU processors, experimenting with different DOP values (such as 4 or 8) may improve performance.

  Contrast DEGREE with DOP, which specifies parallelism at the session level. DEGREE is recommended over DOP for use with the Jena Adapter, because DEGREE involves less processing overhead.

• DOP=n specifies, at the session level, the degree of parallelism (n) for the query. With multi-core or multi-CPU processors, experimenting with different DOP values (such as 4 or 8) may improve performance.

• INF_ONLY causes only the inferred model to be queried.

• JENA_EXECUTOR disables the compilation of SPARQL queries to SEM_MATCH (or native SQL); instead, the Jena native query executor will be used.

• JOIN=n specifies how results from a SPARQL SERVICE call to a federated query can be joined with other parts of the query. For information about federated queries and the JOIN option, see Section 7.6.4.1.

• NO_FALL_BACK causes the underlying query execution engine not to fall back on the Jena execution mechanism if a SQL exception occurs.

• ODS=n specifies, at the statement level, the level of dynamic sampling. (For an explanation of dynamic sampling, see the section about estimating statistics with dynamic sampling in Oracle Database Performance Tuning Guide.) Valid values for n are 1 through 10. For example, you could try ODS=3 for complex queries.

• ORDERED is translated to a LEADING SQL hint for the query triple pattern joins, while performing the necessary RDF_VALUE$ joins last.

• PLAIN_SQL_OPT=F disables the native compilation of queries directly to SQL.

• QID=n specifies a query ID number; this feature can be used to cancel the query if it is not responding.

• RESULT_CACHE uses the Oracle RESULT_CACHE directive for the query.

• REWRITE=F disables ODCI_Table_Rewrite for the SEM_MATCH table function.

• SKIP_CLOB=T causes CLOB values not to be returned for the query.

• S2S (SPARQL to pure SQL) causes the underlying SEM_MATCH-based query or queries generated based on the SPARQL query to be further converted into SQL queries without using the SEM_MATCH table function. The resulting SQL queries are executed by the Oracle cost-based optimizer, and the results are processed by the Jena Adapter before being passed on to the client. For more information about the S2S option, including benefits and usage information, see Section 7.6.4.2.

• TIMEOUT=n (query timeout) specifies the number of seconds (n) that the query will run until it is terminated. The underlying SQL generated from a SPARQL query can return many matches and can use features like subqueries and assignments, all of which can take considerable time. The TIMEOUT and BEST_EFFORT_QUERY=t options can be used to prevent what you consider excessive processing time for the query.

SELECT ?s ?s1 ?o
 WHERE { ?s1 ?p1 ?s .
                    {
                     SERVICE <http://sparql.org/books> { ?s ?p ?o }
                    }
                 }

PREFIX ORACLE_SEM_FS_NS:   <http://oracle.com/semtech#join=2>
SELECT ?s ?s1 ?o
 WHERE { ?s1 ?p1 ?s .
                    {
                     SERVICE <http://sparql.org/books> { ?s ?p ?o }
                    }
                 }

PREFIX ORACLE_SEM_FS_NS:   <http://oracle.com/semtech#join=3>
SELECT ?s ?s1 ?o
 WHERE { ?s1 ?p1 ?s .
                    {
                     SERVICE <http://sparql.org/books> { ?s ?p ?o }
                    }
                  }

PREFIX ORACLE_SEM_FS_NS:   <http://oracle.com/semtech#join=1>
SELECT ?s ?s1 ?o
 WHERE { ?s1 ?p1 ?s .
                    {
                     SERVICE <http://sparql.org/books> { ?s ?p ?o }
                    }
                }

-Doracle.spatial.rdf.client.jena.queryCacheSize=<size>

7.6.5 Midtier Resource Caching

When semantic data is stored, all of the resource values are hashed into IDs, which are stored in the triples table. The mappings from value IDs to full resource values are stored in the MDSYS.RDF_VALUE$ table. At query time, for each selected variable, Oracle Database must perform a join with the RDF_VALUE$ table to retrieve the resource.

However, to reduce the number of joins, you can use the midtier cache option, which causes an in-memory cache on the middle tier to be used for storing mappings between value IDs and resource values. To use this feature, include the following PREFIX pragma in the SPARQL query:

PREFIX ORACLE_SEM_FS_NS: <http://oracle.com/semtech#midtier_cache>

To control the maximum size (in bytes) of the in-memory cache, use the oracle.spatial.rdf.client.jena.cacheMaxSize system property. The default cache maximum size is 1GB.

Note that midtier resource caching is most effective for queries using ORDER BY or DISTINCT (or both) constructs. Midtier cache can be combined with the other options specified in Section 7.6.4.

If you want to pre-populate the cache with all of the resources in a model, use the GraphOracleSem.populateCache method.

7.7.1 Functions in the ARQ Function Library

SPARQL queries through the Jena Adapter can use functions in the function library of the Jena ARQ query engine. These queries are executed in the middle tier.

The following examples use the upper-case and namespace functions. In these examples, the prefix fn is <http://www.w3.org/2005/xpath-functions#> and the prefix afn is <http://jena.hpl.hp.com/ARQ/function#>.

PREFIX  fn: <http://www.w3.org/2005/xpath-functions#>
PREFIX  afn: <http://jena.hpl.hp.com/ARQ/function#>
SELECT (fn:upper-case(?object) as ?object1)
WHERE { ?subject dc:title ?object }

PREFIX  fn: <http://www.w3.org/2005/xpath-functions#>
PREFIX  afn: <http://jena.hpl.hp.com/ARQ/function#>
SELECT ?subject (afn:namespace(?object) as ?object1)
WHERE { ?subject <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> ?object } 

7.7.2 Native Oracle Database Functions for Projected Variables

SPARQL queries through the Jena Adapter can use native Oracle Database functions for projected variables. These queries and the functions are executed inside the database. Note that the functions described in this section should not be used together with ARQ functions (described in Section 7.7.1).

This section lists the supported native functions and provides some examples. In the examples, the prefix oext is <http://oracle.com/semtech/jena-adaptor/ext/function#>.

• oext:upper-literal converts literal values (except for long literals) to uppercase. For example:

  PREFIX  oext: <http://oracle.com/semtech/jena-adaptor/ext/function#>
  SELECT (oext:upper-literal(?object) as ?object1)
  WHERE { ?subject dc:title ?object }
  

• oext:lower-literal converts literal values (except for long literals) to lowercase. For example:

  PREFIX  oext: <http://oracle.com/semtech/jena-adaptor/ext/function#>
  SELECT (oext:lower-literal(?object) as ?object1)
  WHERE { ?subject dc:title ?object }
  

• oext:build-uri-for-id converts the value ID of a URI, bNode, or literal into a URI form. For example:

  PREFIX  oext: <http://oracle.com/semtech/jena-adaptor/ext/function#>
  SELECT (oext:build-uri-for-id(?object) as ?object1)
  WHERE { ?subject dc:title ?object }
  

  An example of the output might be: <rdfvid:1716368199350136353>

  One use of this function is to allow Java applications to maintain in memory a mapping of those value IDs to the lexical form of URIs, bNodes, or literals. The MDSYS.RDF_VALUE$ table provides such a mapping in Oracle Database.

  For a given variable ?var, if only oext:build-uri-for-id(?var) is projected, the query performance is likely to be faster because fewer internal table join operations are needed to answer the query.

• oext:literal-strlen returns the length of literal values (except for long literals). For example:

  PREFIX  oext: <http://oracle.com/semtech/jena-adaptor/ext/function#>
  SELECT (oext:literal-strlen(?object) as ?objlen)
  WHERE { ?subject dc:title ?object }
  

7.7.3 User-Defined Functions

SPARQL queries through the Jena Adapter can use user-defined functions that are stored in the database.

In the following example, assume that you want to define a string length function (my_strlen) that handles long literals (CLOB) as well as short literals. On the SPARQL query side, this function can be referenced under the namespace of ouext, which is http://oracle.com/semtech/jena-adaptor/ext/user-def-function#.

PREFIX  ouext: <http://oracle.com/semtech/jena-adaptor/ext/user-def-function#>
SELECT ?subject ?object (ouext:my_strlen(?object) as ?obj1)
WHERE { ?subject dc:title ?object }

Inside the database, functions including my_strlen, my_strlen_cl, my_strlen_la, my_strlen_lt, and my_strlen_vt are defined to implement this capability. Conceptually, the return values of these functions are mapped as shown in Table 7-1.

A set of functions (five in all) is used to implement a user-defined function that can be referenced from SPARQL, because this aligns with the internal representation of an RDF resource (in MDSYS.RDF_VALUE$). There are five major columns describing an RDF resource in terms of its value, language, literal type, long value, and value type, and these five columns can be selected out using SEM_MATCH. In this context, a user-defined function simply converts one RDF resource that is represented by five columns to another RDF resource.

These functions are defined as follows:

create or replace function my_strlen(rdfvtyp in varchar2,
                              rdfltyp in varchar2,
                              rdflang in varchar2,
                              rdfclob in clob,
                              value   in varchar2
                              ) return varchar2
 as
   ret_val  varchar2(4000);
 begin
   -- value
   if (rdfvtyp = 'LIT') then
     if (rdfclob is null) then
       return length(value);
     else
       return dbms_lob.getlength(rdfclob);
     end if;
   else
     -- Assign -1 for non-literal values so that application can
     -- easily differentiate
     return '-1';
   end if;
 end;
 /
 
 create or replace function my_strlen_cl(rdfvtyp in varchar2,
                              rdfltyp in varchar2,
                              rdflang in varchar2,
                              rdfclob in clob,
                              value   in varchar2
                              ) return clob
 as
 begin
   return null;
 end;
 /
 
 create or replace function my_strlen_la(rdfvtyp in varchar2,
                              rdfltyp in varchar2,
                              rdflang in varchar2,
                              rdfclob in clob,
                              value   in varchar2
                              ) return varchar2
 as
 begin
   return null;
 end;
 /
 
 create or replace function my_strlen_lt(rdfvtyp in varchar2,
                              rdfltyp in varchar2,
                              rdflang in varchar2,
                              rdfclob in clob,
                              value   in varchar2
                              ) return varchar2
 as
   ret_val  varchar2(4000);
 begin
   -- literal type
   return 'http://www.w3.org/2001/XMLSchema#integer';
 end;
 /
 
 create or replace function my_strlen_vt(rdfvtyp in varchar2,
                              rdfltyp in varchar2,
                              rdflang in varchar2,
                              rdfclob in clob,
                              value   in varchar2
                              ) return varchar2
 as
   ret_val  varchar2(3);
 begin
   return 'LIT';
 end;
 /

User-defined functions can also accept a parameter of VARCHAR2 type. The following five functions together define a my_shorten_str function that accepts an integer (in VARCHAR2 form) for the substring length and returns the substring. (The substring in this example is 12 characters, and it must not be greater than 4000 bytes.)

-- SPARQL query that returns the first 12 characters of literal values.
-- 
PREFIX  ouext: <http://oracle.com/semtech/jena-adaptor/ext/user-def-function#>
SELECT (ouext:my_shorten_str(?object, "12") as ?obj1) ?subject
WHERE { ?subject dc:title ?object }
 
create or replace function my_shorten_str(rdfvtyp in varchar2,
                            rdfltyp in varchar2,
                            rdflang in varchar2,
                            rdfclob in clob,
                            value   in varchar2,
                            arg     in varchar2
                            ) return varchar2
as
 ret_val  varchar2(4000);
begin
 -- value
 if (rdfvtyp = 'LIT') then
   if (rdfclob is null) then
     return substr(value, 1, to_number(arg));
   else
     return dbms_lob.substr(rdfclob, to_number(arg), 1);
   end if;
 else
   return null;
 end if;
end;
/
 
create or replace function my_shorten_str_cl(rdfvtyp in varchar2,
                            rdfltyp in varchar2,
                            rdflang in varchar2,
                            rdfclob in clob,
                            value   in varchar2,
                            arg     in varchar2
                            ) return clob
as
 ret_val  clob;
begin
 -- lob
 return null;
end;
/
 
create or replace function my_shorten_str_la(rdfvtyp in varchar2,
                            rdfltyp in varchar2,
                            rdflang in varchar2,
                            rdfclob in clob,
                            value   in varchar2,
                            arg     in varchar2
                            ) return varchar2
as
 ret_val  varchar2(4000);
begin
 -- lang
 if (rdfvtyp = 'LIT') then
   return rdflang;
 else
   return null;
 end if;
end;
/
 
create or replace function my_shorten_str_lt(rdfvtyp in varchar2,
                            rdfltyp in varchar2,
                            rdflang in varchar2,
                            rdfclob in clob,
                            value   in varchar2,
                            arg     in varchar2
                            ) return varchar2
as
 ret_val  varchar2(4000);
begin
 -- literal type
 ret_val := rdfltyp;
 return ret_val;
end;
/
 
create or replace function my_shorten_str_vt(rdfvtyp in varchar2,
                            rdfltyp in varchar2,
                            rdflang in varchar2,
                            rdfclob in clob,
                            value   in varchar2,
                            arg     in varchar2
                            ) return varchar2
as
 ret_val  varchar2(3);
begin
 return 'LIT';
end;
/

7.8.1 Virtual Models Support

Virtual models (explained in Section 1.3.8) are specified in the GraphOracleSem constructor, and they are handled transparently. If a virtual model exists for the model-rulebase combination, it is used in query answering; if such a virtual model does not exist, it is created in the database.

The following example reuses an existing virtual model.

String modelName = "EX";
String m1 = "EX_1";
 
ModelOracleSem defaultModel = 
  ModelOracleSem.createOracleSemModel(oracle, modelName);
 
// create these models in case they don't exist
ModelOracleSem model1 = ModelOracleSem.createOracleSemModel(oracle, m1);
 
String vmName = "VM_" + modelName;
 
 
//create a virtual model containing EX and EX_1
oracle.executeCall(
"begin sem_apis.create_virtual_model(?,sem_models('"+ m1 + "','"+ modelName+"'),null); end;",vmName);
 
String[] modelNames = {m1};
String[] rulebaseNames = {};
 
Attachment attachment = Attachment.createInstance(modelNames, rulebaseNames, 
InferenceMaintenanceMode.NO_UPDATE, QueryOptions.ALLOW_QUERY_VALID_AND_DUP);
 
// vmName is passed to the constructor, so GraphOracleSem will use the virtual 
// model named vmname (if the current user has read privileges on it)
GraphOracleSem graph = new GraphOracleSem(oracle, modelName, attachment, vmName);
graph.add(Triple.create(Node.createURI("urn:alice"),
                        Node.createURI("http://xmlns.com/foaf/0.1/mbox"),
                        Node.createURI("mailto:alice@example")));
ModelOracleSem model = new ModelOracleSem(graph);          
 
String queryString =
 
   " SELECT ?subject ?object WHERE { ?subject ?p ?object } ";
 
Query query = QueryFactory.create(queryString) ;
QueryExecution qexec = QueryExecutionFactory.create(query, model) ;
 
try {
   ResultSet results = qexec.execSelect() ;
   for ( ; results.hasNext() ; ) {
      QuerySolution soln = results.nextSolution() ;
      psOut.println("soln " + soln);
   }
} 
finally { 
   qexec.close() ; 
}
 
OracleUtils.dropSemanticModel(oracle, modelName);
OracleUtils.dropSemanticModel(oracle, m1);
 
oracle.dispose();

You can also use the GraphOracleSem constructor to create a virtual model, as in the following example:

GraphOracleSem graph = new GraphOracleSem(oracle, modelName, attachment, true);

In this example, the fourth parameter (true) specifies that a virtual model needs to be created for the specified modelName and attachment.

7.8.2 Connection Pooling Support

Oracle Database Connection Pooling is provided through the Jena Adapter OraclePool class. Once this class is initialized, it can return Oracle objects out of its pool of available connections. Oracle objects are essentially database connection wrappers. After dispose is called on the Oracle object, the connection is returned to the pool. More information about using OraclePool can be found in the API reference information (Javadoc).

The following example sets up an OraclePool object with five (5) initial connections.

public static void main(String[] args) throws Exception
  {      
    String szJdbcURL = args[0];
    String szUser    = args[1];
    String szPasswd  = args[2];
    String szModelName = args[3];
 
    // test with connection properties 
    java.util.Properties prop = new java.util.Properties();
    prop.setProperty("MinLimit", "2");     // the cache size is 2 at least 
    prop.setProperty("MaxLimit", "10");
    prop.setProperty("InitialLimit", "2"); // create 2 connections at startup
    prop.setProperty("InactivityTimeout", "1800");    //  seconds
    prop.setProperty("AbandonedConnectionTimeout", "900");  //  seconds
    prop.setProperty("MaxStatementsLimit", "10");
    prop.setProperty("PropertyCheckInterval", "60"); // seconds
 
    System.out.println("Creating OraclePool");
    OraclePool op = new OraclePool(szJdbcURL, szUser, szPasswd, prop, 
               "OracleSemConnPool");
    System.out.println("Done creating OraclePool");
 
    // grab an Oracle and do something with it
    System.out.println("Getting an Oracle from OraclePool");
    Oracle oracle = op.getOracle();
    System.out.println("Done");
    System.out.println("Is logical connection:" +
        oracle.getConnection().isLogicalConnection());
    GraphOracleSem g = new GraphOracleSem(oracle, szModelName);
    g.add(Triple.create(Node.createURI("u:John"), 
                        Node.createURI("u:parentOf"), 
                        Node.createURI("u:Mary")));
    g.close();
    // return the Oracle back to the pool
    oracle.dispose();
    
    // grab another Oracle and do something else 
    System.out.println("Getting an Oracle from OraclePool");
    oracle = op.getOracle();
    System.out.println("Done");
    System.out.println("Is logical connection:" +
        oracle.getConnection().isLogicalConnection());
    g = new GraphOracleSem(oracle, szModelName);
    g.add(Triple.create(Node.createURI("u:John"), 
                        Node.createURI("u:parentOf"), 
                        Node.createURI("u:Jack")));
    g.close();
    
    OracleUtils.dropSemanticModel(oracle, szModelName); 
    
    // return the Oracle object back to the pool
    oracle.dispose();
}

7.8.3 Semantic Model PL/SQL Interfaces

Several semantic PL/SQL subprograms are available through the Jena Adapter. Table 7-2 lists the subprograms and their corresponding Java class and methods.

For information about these PL/SQL utility subprograms, see the reference information in Chapter 9. For information about the corresponding Java class and methods, see the Jena Adapter API Reference documentation (Javadoc).

7.8.4 Inference Options

You can add options to entailment calls by using the setInferenceOption(String options) procedure with the GraphOracleSem constructor. The following example enables incremental inference and specifies a parallelism value of 4 when creating an entailment.

graph.setInferenceOption("INC=T,DOP=4");

For information about inference options, see Section 2.2.

7.8.5 PelletInfGraph Class Support Deprecated

The support for the PelletInfGraph class within the Jena Adapter is deprecated. You should instead use the more optimized Oracle/Pellet integration through the PelletDb OWL 2 reasoner for Oracle Database 11g. (For information about PelletDb, see http://clarkparsia.com/pelletdb/.)

7.10.1 Test.java: Query Family Relationships

Example 7-4 specifies that John is the father of Mary, and it selects and displays the subject and object in each fatherOf relationship

import oracle.spatial.rdf.client.jena.*;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.graph.*;
import com.hp.hpl.jena.query.*;
public class Test {
 
  public static void main(String[] args) throws Exception
  {
    String szJdbcURL = args[0];
    String szUser    = args[1];
    String szPasswd  = args[2];
    String szModelName = args[3];
          
    Oracle oracle = new Oracle(szJdbcURL, szUser, szPasswd);
    Model model = ModelOracleSem.createOracleSemModel(
      oracle, szModelName);
 
    model.getGraph().add(Triple.create(
          Node.createURI("http://example.com/John"),
          Node.createURI("http://example.com/fatherOf"),
          Node.createURI("http://example.com/Mary")));
    Query query = QueryFactory.create(
        "select ?f ?k WHERE {?f <http://example.com/fatherOf> ?k .}");
    QueryExecution qexec = QueryExecutionFactory.create(query, model);
    ResultSet results = qexec.execSelect();
    ResultSetFormatter.out(System.out, results, query);
    model.close();
    oracle.dispose();
  }
}

The following are the commands to compile and run Example 7-4, as well as the expected output of the java command.

javac -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:/slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar Test.java
java -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:./slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar:./iri-0.8.jar:./icu4j-3.4.4.jar:./log4j-1.2.14.jar  Test jdbc:oracle:thin:@localhost:1521:orcl scott <password-for-scott> M1
 
---------------------------------------------------------
| f                         | k                         |
=========================================================
| <http://example.com/John> | <http://example.com/Mary> |
---------------------------------------------------------

7.10.2 Test6.java: Load OWL Ontology and Perform OWLPrime inference

Example 7-5 loads an OWL ontology and performs OWLPrime inference. Note that the OWL ontology is in RDF/XML format, and after it is loaded into Oracle it will be serialized out in N-TRIPLE form. The example also queries for the number of asserted and inferred triples.

The ontology in this example can be retrieved from http://www.lehigh.edu/~zhp2/2004/0401/univ-bench.owl, and it describes roles, resources, and relationships in a university environment.

import java.io.*;
import com.hp.hpl.jena.query.*;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.util.FileManager;
import oracle.spatial.rdf.client.jena.*;
public class Test6 {
  public static void main(String[] args) throws Exception
  {
    String szJdbcURL = args[0];
    String szUser    = args[1];
    String szPasswd  = args[2];
    String szModelName = args[3];
    
    Oracle oracle = new Oracle(szJdbcURL, szUser, szPasswd);
    Model model = ModelOracleSem.createOracleSemModel(oracle, szModelName);
        
    // load UNIV ontology
    InputStream in = FileManager.get().open("./univ-bench.owl" );
    model.read(in, null);
    OutputStream os = new FileOutputStream("./univ-bench.nt");
    model.write(os, "N-TRIPLE");
    os.close();
 
    String queryString =
      " SELECT ?subject ?prop ?object WHERE { ?subject ?prop ?object } ";
 
    Query query = QueryFactory.create(queryString) ;
    QueryExecution qexec = QueryExecutionFactory.create(query, model) ;
 
    try {
      int iTriplesCount = 0;
      ResultSet results = qexec.execSelect() ;
      for ( ; results.hasNext() ; ) {
        QuerySolution soln = results.nextSolution() ;
        iTriplesCount++;
      }
      System.out.println("Asserted  triples count: " + iTriplesCount);
    } 
    finally { 
      qexec.close() ; 
    }
    
    Attachment attachment = Attachment.createInstance(
        new String[] {}, "OWLPRIME",
        InferenceMaintenanceMode.NO_UPDATE, QueryOptions.DEFAULT);
 
    GraphOracleSem graph = new GraphOracleSem(oracle, szModelName, attachment);
    graph.analyze();
    graph.performInference();
 
    query = QueryFactory.create(queryString) ;
    qexec = QueryExecutionFactory.create(query,new ModelOracleSem(graph)) ;
 
    try {
      int iTriplesCount = 0;
      ResultSet results = qexec.execSelect() ;
      for ( ; results.hasNext() ; ) {
        QuerySolution soln = results.nextSolution() ;
        iTriplesCount++;
      }
      System.out.println("Asserted + Infered triples count: " + iTriplesCount);
    } 
    finally { 
      qexec.close() ; 
    }
    model.close();    
 
    OracleUtils.dropSemanticModel(oracle, szModelName);    
    oracle.dispose();
  }
}

The following are the commands to compile and run Example 7-5, as well as the expected output of the java command.

javac -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:/slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar Test6.java
java -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:./slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar:./iri-0.8.jar:./icu4j-3.4.4.jar:./log4j-1.2.14.jar  Test6 jdbc:oracle:thin:@localhost:1521:orcl scott <password-for-scott> M1
Asserted  triples count: 294
Asserted + Infered triples count: 341

Note that this output reflects an older version of the LUBM ontology. The latest version of the ontology has more triples.

7.10.3 Test7.java: Bulk Load OWL Ontology and Perform OWLPrime inference

Example 7-6 loads the same OWL ontology as in Section 7.10.2, but stored in a local file using Bulk Loader. Ontologies can also be loaded using an incremental and batch loader; these two methods are also listed in the example for completeness.

import java.io.*;
import com.hp.hpl.jena.query.*;
import com.hp.hpl.jena.graph.*;
import com.hp.hpl.jena.rdf.model.*;
import com.hp.hpl.jena.util.*;
import oracle.spatial.rdf.client.jena.*;
 
public class Test7 
{
  public static void main(String[] args) throws Exception
  {
    String szJdbcURL = args[0];
    String szUser    = args[1];
    String szPasswd  = args[2];
    String szModelName = args[3];
    // in memory Jena Model
    Model model = ModelFactory.createDefaultModel();
    InputStream is = FileManager.get().open("./univ-bench.owl");
    model.read(is, "", "RDF/XML");
    is.close();
 
    Oracle oracle = new Oracle(szJdbcURL, szUser, szPasswd);
    ModelOracleSem modelDest = ModelOracleSem.createOracleSemModel(oracle, 
szModelName);
 
    GraphOracleSem g = modelDest.getGraph();
    g.dropApplicationTableIndex();
 
    int method = 2; // try bulk loader
    String tbs = "SYSAUX"; // can be customized
    if (method == 0) {
      System.out.println("start incremental");
      modelDest.add(model);
      System.out.println("end size " + modelDest.size());
    }
    else if (method == 1) {
      System.out.println("start batch load");
      g.getBulkUpdateHandler().addInBatch(
          GraphUtil.findAll(model.getGraph()), tbs);
      System.out.println("end size " + modelDest.size());
    }
    else {
      System.out.println("start bulk load");
      g.getBulkUpdateHandler().addInBulk(
          GraphUtil.findAll(model.getGraph()), tbs);
      System.out.println("end size " + modelDest.size());
    }
    g.rebuildApplicationTableIndex();
 
    long lCount = g.getCount(Triple.ANY);
    System.out.println("Asserted  triples count: " + lCount);
    model.close();    
    OracleUtils.dropSemanticModel(oracle, szModelName);
    oracle.dispose();
  }
}

The following are the commands to compile and run Example 7-6, as well as the expected output of the java command.

javac -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:/slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar Test7.java
java -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:./slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar:./iri-0.8.jar:./icu4j-3.4.4.jar:./log4j-1.2.14.jar  Test7 jdbc:oracle:thin:@localhost:1521:orcl scott <password-for-scott> M1
start bulk load
end size 293
Asserted  triples count: 293

Note that this output reflects an older version of the LUBM ontology. The latest version of the ontology has more triples.

7.10.4 Test8.java: SPARQL OPTIONAL Query

Example 7-7 shows a SPARQL OPTIONAL query. It inserts triples that postulate the following:

• John is a parent of Mary.

• John is a parent of Jack.

• Mary is a parent of Jill.

It then finds parent-child relationships, optionally including any grandchild (gkid) relationships.

import java.io.*;
import com.hp.hpl.jena.query.*;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.util.FileManager;
import oracle.spatial.rdf.client.jena.*;
import com.hp.hpl.jena.graph.*;
 
public class Test8 
{
  public static void main(String[] args) throws Exception
  {
    String szJdbcURL = args[0];
    String szUser    = args[1];
    String szPasswd  = args[2];
    String szModelName = args[3];
    
    Oracle oracle = new Oracle(szJdbcURL, szUser, szPasswd);
    ModelOracleSem model = ModelOracleSem.createOracleSemModel(oracle, 
szModelName);
    GraphOracleSem g = model.getGraph();
 
    g.add(Triple.create(
          Node.createURI("u:John"), Node.createURI("u:parentOf"), 
Node.createURI("u:Mary")));
    g.add(Triple.create(
          Node.createURI("u:John"), Node.createURI("u:parentOf"), 
Node.createURI("u:Jack")));
    g.add(Triple.create(
          Node.createURI("u:Mary"), Node.createURI("u:parentOf"), 
Node.createURI("u:Jill")));
        
    String queryString =
  " SELECT ?s ?o ?gkid " +
  " WHERE { ?s <u:parentOf> ?o . OPTIONAL {?o <u:parentOf> ?gkid }} ";
 
    Query query = QueryFactory.create(queryString) ;
    QueryExecution qexec = QueryExecutionFactory.create(query, model) ;
 
    try {
      int iMatchCount = 0;
      ResultSet results = qexec.execSelect() ;
      ResultSetFormatter.out(System.out, results, query);
    } 
    finally { 
      qexec.close() ; 
    }
    model.close();    
 
    OracleUtils.dropSemanticModel(oracle, szModelName);
    oracle.dispose();
  }
}

The following are the commands to compile and run Example 7-7, as well as the expected output of the java command.

javac -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:/slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar Test8.java
java -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:./slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar:./iri-0.8.jar:./icu4j-3.4.4.jar:./log4j-1.2.14.jar  Test8 jdbc:oracle:thin:@localhost:1521:orcl scott <password-for-scott> M1
----------------------------------
| s        | o        | gkid     |
==================================
| <u:John> | <u:Mary> | <u:Jill> |
| <u:Mary> | <u:Jill> |          |
| <u:John> | <u:Jack> |          |
---------------------------------- 

7.10.5 Test9.java: SPARQL Query with LIMIT and OFFSET

Example 7-8 shows a SPARQL query with LIMIT and OFFSET. It inserts triples that postulate the following:

• John is a parent of Mary.

• John is a parent of Jack.

• Mary is a parent of Jill.

It then finds one parent-child relationship (LIMIT 1), skipping the first two parent-child relationships encountered (OFFSET 2), and optionally includes any grandchild (gkid) relationships for the one found.

import java.io.*;
import com.hp.hpl.jena.query.*;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.util.FileManager;
import oracle.spatial.rdf.client.jena.*;
import com.hp.hpl.jena.graph.*;
public class Test9 
{
  public static void main(String[] args) throws Exception
  {
    String szJdbcURL = args[0];
    String szUser    = args[1];
    String szPasswd  = args[2];
    String szModelName = args[3];
    
    Oracle oracle = new Oracle(szJdbcURL, szUser, szPasswd);
    ModelOracleSem model = ModelOracleSem.createOracleSemModel(oracle, 
szModelName);
    GraphOracleSem g = model.getGraph();
 
    g.add(Triple.create(Node.createURI("u:John"), Node.createURI("u:parentOf"),
                    Node.createURI("u:Mary")));
    g.add(Triple.create(Node.createURI("u:John"), Node.createURI("u:parentOf"),
                    Node.createURI("u:Jack")));
    g.add(Triple.create(Node.createURI("u:Mary"), Node.createURI("u:parentOf"),              
                    Node.createURI("u:Jill")));
        
    String queryString =
      " SELECT ?s ?o ?gkid " +
      " WHERE { ?s <u:parentOf> ?o . OPTIONAL {?o <u:parentOf> ?gkid }} " +
      " LIMIT 1 OFFSET 2";
 
    Query query = QueryFactory.create(queryString) ;
    QueryExecution qexec = QueryExecutionFactory.create(query, model) ;
 
    int iMatchCount = 0;
    ResultSet results = qexec.execSelect() ;
    ResultSetFormatter.out(System.out, results, query);
    qexec.close() ; 
    model.close();    
 
    OracleUtils.dropSemanticModel(oracle, szModelName);
    oracle.dispose();
  }
}

The following are the commands to compile and run Example 7-8, as well as the expected output of the java command.

javac -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:/slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar Test9.java
java -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:./slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar:./iri-0.8.jar:./icu4j-3.4.4.jar:./log4j-1.2.14.jar  Test9 jdbc:oracle:thin:@localhost:1521:orcl scott <password-for-scott> M1
------------------------------
| s        | o        | gkid |
==============================
| <u:John> | <u:Jack> |      |
------------------------------ 

7.10.6 Test10.java: SPARQL Query with TIMEOUT and DOP

Example 7-9 shows the SPARQL query from Section 7.10.5 with additional features, including a timeout setting (TIMEOUT=1, in seconds) and parallel execution setting (DOP=4).

import java.io.*;
import com.hp.hpl.jena.query.*;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.util.FileManager;
import oracle.spatial.rdf.client.jena.*;
import com.hp.hpl.jena.graph.*;
 
public class Test10 {
  public static void main(String[] args) throws Exception  {
    String szJdbcURL = args[0];
    String szUser    = args[1];
    String szPasswd  = args[2];
    String szModelName = args[3];
    
    Oracle oracle = new Oracle(szJdbcURL, szUser, szPasswd);
    ModelOracleSem model = ModelOracleSem.createOracleSemModel(oracle, szModelName);
    GraphOracleSem g = model.getGraph();
 
    g.add(Triple.create(Node.createURI("u:John"), Node.createURI("u:parentOf"), 
                            Node.createURI("u:Mary")));
    g.add(Triple.create(Node.createURI("u:John"), Node.createURI("u:parentOf"), 
                        Node.createURI("u:Jack")));
    g.add(Triple.create(Node.createURI("u:Mary"), Node.createURI("u:parentOf"), 
                        Node.createURI("u:Jill")));
    String queryString =
        " PREFIX ORACLE_SEM_FS_NS: <http://oracle.com/semtech#dop=4,timeout=1> " 
      + " SELECT ?s ?o ?gkid WHERE { ?s <u:parentOf> ?o . " 
      + " OPTIONAL {?o <u:parentOf> ?gkid }} "
      + " LIMIT 1 OFFSET 2";
 
    Query query = QueryFactory.create(queryString) ;
    QueryExecution qexec = QueryExecutionFactory.create(query, model) ;
 
    int iMatchCount = 0;
    ResultSet results = qexec.execSelect() ;
    ResultSetFormatter.out(System.out, results, query);
    qexec.close() ; 
    model.close();    
 
    OracleUtils.dropSemanticModel(oracle, szModelName);
    oracle.dispose();
  }
}

The following are the commands to compile and run Example 7-9, as well as the expected output of the java command.

javac -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:/slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar Test10.java
java -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:./slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar:./iri-0.8.jar:./icu4j-3.4.4.jar:./log4j-1.2.14.jar  Test10 jdbc:oracle:thin:@localhost:1521:orcl scott <password-for-scott> M1
------------------------------
| s        | o        | gkid |
==============================
| <u:Mary> | <u:Jill> |      |
------------------------------

7.10.7 Test11.java: Query Involving Named Graphs

Example 7-10 shows a query involving named graphs. It involves a default model that has information about named graph URIs and their publishers. The query finds graph names, their publishers, and within each named graph finds the mailbox value using the foaf:mbox predicate.

import java.io.*;
import com.hp.hpl.jena.query.*;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.util.FileManager;
import oracle.spatial.rdf.client.jena.*;
import com.hp.hpl.jena.graph.*;
 
public class Test11
{
  public static void main(String[] args) throws Exception
  {
    String szJdbcURL = args[0];
    String szUser    = args[1];
    String szPasswd  = args[2];
    String szModelName = args[3];
    
    Oracle oracle = new Oracle(szJdbcURL, szUser, szPasswd);
    DataSource ds = DatasetFactory.create();
    ModelOracleSem model = ModelOracleSem.createOracleSemModel(oracle, szModelName);
    model.getGraph().add(Triple.create(Node.createURI("http://example.org/bob"),
          Node.createURI("http://purl.org/dc/elements/1.1/publisher"),
          Node.createLiteral("Bob Hacker")));
    model.getGraph().add(Triple.create(Node.createURI("http://example.org/alice"),
          Node.createURI("http://purl.org/dc/elements/1.1/publisher"),
          Node.createLiteral("alice Hacker")));
 
 
    ModelOracleSem model1 = ModelOracleSem.createOracleSemModel(oracle,
 szModelName+"1");
 
    model1.getGraph().add(Triple.create(Node.createURI("urn:bob"),
                                        Node.createURI("http://xmlns.com/foaf/0.1/name"),
                                    Node.createLiteral("Bob")));
    model1.getGraph().add(Triple.create(Node.createURI("urn:bob"),
                                     Node.createURI("http://xmlns.com/foaf/0.1/mbox"),
                                     Node.createURI("mailto:bob@example")));
 
    ModelOracleSem model2 = ModelOracleSem.createOracleSemModel(oracle,
            szModelName+"2");
    model2.getGraph().add(Triple.create(Node.createURI("urn:alice"),
                                        Node.createURI("http://xmlns.com/foaf/0.1/name"),
                                    Node.createLiteral("Alice")));
    model2.getGraph().add(Triple.create(Node.createURI("urn:alice"),
                                        Node.createURI("http://xmlns.com/foaf/0.1/mbox"),
                                    Node.createURI("mailto:alice@example")));
 
    ds.setDefaultModel(model);
    ds.addNamedModel("http://example.org/bob",model1);
    ds.addNamedModel("http://example.org/alice",model2);
 
    String queryString =  
      " PREFIX foaf: <http://xmlns.com/foaf/0.1/> "
    + " PREFIX dc: <http://purl.org/dc/elements/1.1/> "
    + " SELECT ?who ?graph ?mbox "
    + " FROM NAMED <http://example.org/alice> "
    + " FROM NAMED <http://example.org/bob> "
    + " WHERE "
    + " { " 
    + "    ?graph dc:publisher ?who . "
    + "    GRAPH ?graph { ?x foaf:mbox ?mbox } "
    + " } ";
 
    Query query = QueryFactory.create(queryString) ;
    QueryExecution qexec = QueryExecutionFactory.create(query, ds) ;
 
    ResultSet results = qexec.execSelect() ;
    ResultSetFormatter.out(System.out, results, query);
    
    qexec.close();
    model.close();    
    model1.close();    
    model2.close();    
 
    OracleUtils.dropSemanticModel(oracle, szModelName);
    OracleUtils.dropSemanticModel(oracle, szModelName + "1");
    OracleUtils.dropSemanticModel(oracle, szModelName + "2");
    oracle.dispose();
  }
}

The following are the commands to compile and run Example 7-10, as well as the expected output of the java command.

javac -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:/slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar Test11.java
java -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:./slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar:./iri-0.8.jar:./icu4j-3.4.4.jar:./log4j-1.2.14.jar  Test11 jdbc:oracle:thin:@localhost:1521:orcl scott <password-for-scott> M1
------------------------------------------------------------------------
| who            | graph                      | mbox                   |
========================================================================
| "alice Hacker" | <http://example.org/alice> | <mailto:alice@example> |
| "Bob Hacker"   | <http://example.org/bob>   | <mailto:bob@example>   |
------------------------------------------------------------------------

7.10.8 Test12.java: SPARQL ASK Query

Example 7-11 shows a SPARQL ASK query. It inserts a triple that postulates that John is a parent of Mary. It then finds whether John is a parent of Mary.

import java.io.*;
import com.hp.hpl.jena.query.*;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.util.FileManager;
import oracle.spatial.rdf.client.jena.*;
import com.hp.hpl.jena.graph.*;
public class Test12
{
  public static void main(String[] args) throws Exception
  {
    String szJdbcURL = args[0];
    String szUser    = args[1];
    String szPasswd  = args[2];
    String szModelName = args[3];
    
    Oracle oracle = new Oracle(szJdbcURL, szUser, szPasswd);
    ModelOracleSem model = ModelOracleSem.createOracleSemModel(oracle, 
          szModelName);
    GraphOracleSem g = model.getGraph();
 
    g.add(Triple.create(Node.createURI("u:John"), Node.createURI("u:parentOf"), 
                        Node.createURI("u:Mary")));
    String queryString = " ASK { <u:John> <u:parentOf> <u:Mary> } ";
 
    Query query = QueryFactory.create(queryString) ;
    QueryExecution qexec = QueryExecutionFactory.create(query, model) ;
    boolean b = qexec.execAsk();
    System.out.println("ask result = " + ((b)?"TRUE":"FALSE"));
    qexec.close() ; 
    
    model.close();    
    OracleUtils.dropSemanticModel(oracle, szModelName);
    oracle.dispose();
  }
}

The following are the commands to compile and run Example 7-11, as well as the expected output of the java command.

javac -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:/slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar Test12.java
java -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:./slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar:./iri-0.8.jar:./icu4j-3.4.4.jar:./log4j-1.2.14.jar  Test12 jdbc:oracle:thin:@localhost:1521:orcl scott <password-for-scott> M1
ask result = TRUE

7.10.9 Test13.java: SPARQL DESCRIBE Query

Example 7-12 shows a SPARQL DESCRIBE query. It inserts triples that postulate the following:

• John is a parent of Mary.

• John is a parent of Jack.

• Amy is a parent of Jack.

It then finds all relationships that involve any parents of Jack.

import java.io.*;
import com.hp.hpl.jena.query.*;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.util.FileManager;
import oracle.spatial.rdf.client.jena.*;
import com.hp.hpl.jena.graph.*;
 
public class Test13
{
  public static void main(String[] args) throws Exception
  {
    String szJdbcURL = args[0];
    String szUser    = args[1];
    String szPasswd  = args[2];
    String szModelName = args[3];
    
    Oracle oracle = new Oracle(szJdbcURL, szUser, szPasswd);
    ModelOracleSem model = ModelOracleSem.createOracleSemModel(oracle, szModelName);
    GraphOracleSem g = model.getGraph();
 
    g.add(Triple.create(Node.createURI("u:John"), Node.createURI("u:parentOf"), 
                    Node.createURI("u:Mary")));
    g.add(Triple.create(Node.createURI("u:John"), Node.createURI("u:parentOf"), 
 Node.createURI("u:Jack")));
    g.add(Triple.create(Node.createURI("u:Amy"), Node.createURI("u:parentOf"), 
 Node.createURI("u:Jack")));
    String queryString = " DESCRIBE ?x WHERE {?x <u:parentOf> <u:Jack>}";
 
    Query query = QueryFactory.create(queryString) ;
    QueryExecution qexec = QueryExecutionFactory.create(query, model) ;
    Model m = qexec.execDescribe();
    System.out.println("describe result = " + m.toString());
 
    qexec.close() ; 
    model.close();    
    OracleUtils.dropSemanticModel(oracle, szModelName);
    oracle.dispose();
  }
}

The following are the commands to compile and run Example 7-12, as well as the expected output of the java command.

javac -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:/slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar Test13.java
java -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:./slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar:./iri-0.8.jar:./icu4j-3.4.4.jar:./log4j-1.2.14.jar  Test13 jdbc:oracle:thin:@localhost:1521:orcl scott <password-for-scott> M1
describe result = <ModelCom   {u:Amy @u:parentOf u:Jack; u:John @u:parentOf u:Jack; u:John @u:parentOf u:Mary} | >

7.10.10 Test14.java: SPARQL CONSTRUCT Query

Example 7-13 shows a SPARQL CONSTRUCT query. It inserts triples that postulate the following:

• John is a parent of Mary.

• John is a parent of Jack.

• Amy is a parent of Jack.

• Each parent loves all of his or her children.

It then constructs an RDF graph with information about who loves whom.

import java.io.*;
import com.hp.hpl.jena.query.*;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.util.FileManager;
import oracle.spatial.rdf.client.jena.*;
import com.hp.hpl.jena.graph.*;
 
public class Test14
{
  public static void main(String[] args) throws Exception
  {
    String szJdbcURL = args[0];
    String szUser    = args[1];
    String szPasswd  = args[2];
    String szModelName = args[3];
    
    Oracle oracle = new Oracle(szJdbcURL, szUser, szPasswd);
    ModelOracleSem model = ModelOracleSem.createOracleSemModel(oracle, szModelName);
    GraphOracleSem g = model.getGraph();
 
    g.add(Triple.create(Node.createURI("u:John"), Node.createURI("u:parentOf"), 
 Node.createURI("u:Mary")));
    g.add(Triple.create(Node.createURI("u:John"), Node.createURI("u:parentOf"), 
 Node.createURI("u:Jack")));
    g.add(Triple.create(Node.createURI("u:Amy"), Node.createURI("u:parentOf"), 
 Node.createURI("u:Jack")));
    String queryString = " CONSTRUCT { ?s <u:loves> ?o } WHERE {?s <u:parentOf> ?o}";
 
    Query query = QueryFactory.create(queryString) ;
    QueryExecution qexec = QueryExecutionFactory.create(query, model) ;
    Model m = qexec.execConstruct();
    System.out.println("Construct result = " + m.toString());
 
    qexec.close() ; 
    model.close();    
    OracleUtils.dropSemanticModel(oracle, szModelName);
    oracle.dispose();
  }
}

The following are the commands to compile and run Example 7-13, as well as the expected output of the java command.

javac -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:/slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar Test14.java
java -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:./slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar:./iri-0.8.jar:./icu4j-3.4.4.jar:./log4j-1.2.14.jar  Test14 jdbc:oracle:thin:@localhost:1521:orcl scott <password-for-scott> M1
Construct result = <ModelCom   {u:Amy @u:loves u:Jack; u:John @u:loves u:Jack; u:John @u:loves u:Mary} | >

7.10.11 Test15.java: Query Multiple Models and Specify "Allow Duplicates"

Example 7-14 queries multiple models and uses the "allow duplicates" option. It inserts triples that postulate the following:

• John is a parent of Jack (in Model 1).

• Mary is a parent of Jack (in Model 2).

• Each parent loves all of his or her children.

It then finds out who loves whom. It searches both models and allows for the possibility of duplicate triples in the models (although there are no duplicates in this example).

import java.io.*;
import com.hp.hpl.jena.query.*;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.util.FileManager;
import oracle.spatial.rdf.client.jena.*;
import com.hp.hpl.jena.graph.*;
 
public class Test15
{
  public static void main(String[] args) throws Exception
  {
    String szJdbcURL = args[0];
    String szUser    = args[1];
    String szPasswd  = args[2];
    String szModelName1 = args[3];
    String szModelName2 = args[4];
    
    Oracle oracle = new Oracle(szJdbcURL, szUser, szPasswd);
    ModelOracleSem model1 = ModelOracleSem.createOracleSemModel(oracle, szModelName1);
    model1.getGraph().add(Triple.create(Node.createURI("u:John"), 
                     Node.createURI("u:parentOf"), Node.createURI("u:Jack")));
    model1.close();
 
    ModelOracleSem model2 = ModelOracleSem.createOracleSemModel(oracle, szModelName2);
    model2.getGraph().add(Triple.create(Node.createURI("u:Mary"), 
                     Node.createURI("u:parentOf"), Node.createURI("u:Jack")));
    model2.close();
 
    String[] modelNamesList = {szModelName2};
    String[] rulebasesList  = {};
    Attachment attachment = Attachment.createInstance(modelNamesList, rulebasesList, 
              InferenceMaintenanceMode.NO_UPDATE,
              QueryOptions.ALLOW_QUERY_VALID_AND_DUP);
 
    GraphOracleSem graph = new GraphOracleSem(oracle, szModelName1, attachment);
    ModelOracleSem model = new ModelOracleSem(graph);
 
    String queryString = " CONSTRUCT { ?s <u:loves> ?o } WHERE {?s <u:parentOf> ?o}";
    Query query = QueryFactory.create(queryString) ;
    QueryExecution qexec = QueryExecutionFactory.create(query, model) ;
    Model m = qexec.execConstruct();
    System.out.println("Construct result = " + m.toString());
 
    qexec.close() ; 
    model.close();    
    OracleUtils.dropSemanticModel(oracle, szModelName1);
    OracleUtils.dropSemanticModel(oracle, szModelName2);
    oracle.dispose();
  }
}

The following are the commands to compile and run Example 7-14, as well as the expected output of the java command.

javac -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:/slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar Test15.java
java -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:./slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar:./iri-0.8.jar:./icu4j-3.4.4.jar:./log4j-1.2.14.jar  Test15 jdbc:oracle:thin:@localhost:1521:orcl scott <password-for-scott> M1 M2
Construct result = <ModelCom   {u:Mary @u:loves u:Jack; u:John @u:loves u:Jack} | >

7.10.12 Test16.java: SPARUL (SPARQL Update) Example

Example 7-15 inserts two triples into a model.

import java.io.*;
import com.hp.hpl.jena.query.*;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.util.FileManager;
import com.hp.hpl.jena.util.iterator.*;
import oracle.spatial.rdf.client.jena.*;
import com.hp.hpl.jena.graph.*;
import com.hp.hpl.jena.update.*;
 
public class Test16
{
  public static void main(String[] args) throws Exception
  {
    String szJdbcURL = args[0];
    String szUser    = args[1];
    String szPasswd  = args[2];
    String szModelName = args[3];
    
    Oracle oracle = new Oracle(szJdbcURL, szUser, szPasswd);
    ModelOracleSem model = ModelOracleSem.createOracleSemModel(oracle, szModelName);
    GraphOracleSem g = model.getGraph();
    String insertString =  
      " PREFIX dc: <http://purl.org/dc/elements/1.1/> "         + 
      " INSERT DATA "                                           +
      " { <http://example/book3> dc:title    \"A new book\" ; " +
      "                         dc:creator  \"A.N.Other\" . "   + 
      " }   ";
 
    UpdateAction.parseExecute(insertString,  model);
    ExtendedIterator ei = GraphUtil.findAll(g);
    while (ei.hasNext()) {
      System.out.println("Triple " + ei.next().toString());
    }
    model.close();    
    OracleUtils.dropSemanticModel(oracle, szModelName);
    oracle.dispose();
  }
}

The following are the commands to compile and run Example 7-15, as well as the expected output of the java command.

javac -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:/slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar Test16.java
java -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:./slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar:./iri-0.8.jar:./icu4j-3.4.4.jar:./log4j-1.2.14.jar  Test16 jdbc:oracle:thin:@localhost:1521:orcl scott <password-for-scott> M1
Triple http://example/book3 @dc:title "A new book"
Triple http://example/book3 @dc:creator "A.N.Other"

7.10.13 Test17.java: SPARQL Query with ARQ Built-In Functions

Example 7-16 inserts data about two books, and it displays the book titles in all uppercase characters and the length of each title string.

import java.io.*;
import com.hp.hpl.jena.query.*;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.util.FileManager;
import com.hp.hpl.jena.util.iterator.*;
import oracle.spatial.rdf.client.jena.*;
import com.hp.hpl.jena.graph.*;
import com.hp.hpl.jena.update.*;
 
public class Test17 {
  public static void main(String[] args) throws Exception  {
    String szJdbcURL = args[0];
    String szUser    = args[1];
    String szPasswd  = args[2];
    String szModelName = args[3];
    
    Oracle oracle = new Oracle(szJdbcURL, szUser, szPasswd);
    ModelOracleSem model = ModelOracleSem.createOracleSemModel(oracle, szModelName);
    GraphOracleSem g = model.getGraph();
    String insertString =  
      " PREFIX dc: <http://purl.org/dc/elements/1.1/> "         + 
      " INSERT DATA "                                           +
      " { <http://example/book3> dc:title    \"A new book\" ; " +
      "                         dc:creator  \"A.N.Other\" . "   + 
      "   <http://example/book4> dc:title    \"Semantic Web Rocks\" ; " +
      "                         dc:creator  \"TB\" . "   + 
      " }   ";
 
    UpdateAction.parseExecute(insertString,  model);
    String queryString = "PREFIX  dc:   <http://purl.org/dc/elements/1.1/> " +
      " PREFIX  fn: <http://www.w3.org/2005/xpath-functions#> " + 
      " SELECT ?subject (fn:upper-case(?object) as ?object1)  " + 
      "                 (fn:string-length(?object) as ?strlen) " + 
      " WHERE { ?subject dc:title ?object } " 
      ;
    Query query = QueryFactory.create(queryString, Syntax.syntaxARQ);
    QueryExecution qexec = QueryExecutionFactory.create(query, model);
    ResultSet results = qexec.execSelect();
    ResultSetFormatter.out(System.out, results, query);
    model.close();    
    OracleUtils.dropSemanticModel(oracle, szModelName);
    oracle.dispose();
  }
}

The following are the commands to compile and run Example 7-16, as well as the expected output of the java command.

javac -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:/slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar Test17.java
java -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:./slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar:./iri-0.8.jar:./icu4j-3.4.4.jar:./log4j-1.2.14.jar  Test17 jdbc:oracle:thin:@localhost:1521:orcl scott <password-for-scott> M1
----------------------------------------------------------
| subject                | object1              | strlen |
==========================================================
| <http://example/book3> | "A NEW BOOK"         | 10     |
| <http://example/book4> | "SEMANTIC WEB ROCKS" | 18     |
----------------------------------------------------------

7.10.14 Test18.java: SELECT Cast Query

Example 7-17 "converts" two Fahrenheit temperatures (18.1 and 32.0) to Celsius temperatures.

import java.io.*;
import com.hp.hpl.jena.query.*;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.util.FileManager;
import com.hp.hpl.jena.util.iterator.*;
import oracle.spatial.rdf.client.jena.*;
import com.hp.hpl.jena.graph.*;
import com.hp.hpl.jena.update.*;
 
public class Test18 {
  public static void main(String[] args) throws Exception  {
    String szJdbcURL = args[0];
    String szUser    = args[1];
    String szPasswd  = args[2];
    String szModelName = args[3];
    
    Oracle oracle = new Oracle(szJdbcURL, szUser, szPasswd);
    ModelOracleSem model = ModelOracleSem.createOracleSemModel(oracle, 
szModelName);
    GraphOracleSem g = model.getGraph();
    String insertString =  
      " PREFIX xsd: <http://www.w3.org/2001/XMLSchema#> " +
      " INSERT DATA "                                     +
      " { <u:Object1> <u:temp>    \"18.1\"^^xsd:float ; " +
      "               <u:name>    \"Foo... \" . "         + 
      "   <u:Object2> <u:temp>    \"32.0\"^^xsd:float ; " +
      "               <u:name>    \"Bar... \" . "         + 
      " }   ";
 
    UpdateAction.parseExecute(insertString,  model);
    String queryString = 
      " PREFIX  fn: <http://www.w3.org/2005/xpath-functions#> " + 
      " SELECT ?subject ((?temp - 32.0)*5/9 as ?celsius_temp) " +
      "WHERE { ?subject <u:temp> ?temp } " 
      ;
    Query query = QueryFactory.create(queryString, Syntax.syntaxARQ);
    QueryExecution qexec = QueryExecutionFactory.create(query, model);
    ResultSet results = qexec.execSelect();
    ResultSetFormatter.out(System.out, results, query);
 
    model.close();    
    OracleUtils.dropSemanticModel(oracle, szModelName);
    oracle.dispose();
  }
}

The following are the commands to compile and run Example 7-17, as well as the expected output of the java command.

javac -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:/slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar Test18.java
java -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:./slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar:./iri-0.8.jar:./icu4j-3.4.4.jar:./log4j-1.2.14.jar  Test18 jdbc:oracle:thin:@localhost:1521:orcl scott <password-for-scott> M1
------------------------------------------------------------------------
| subject     | celsius_temp                                           |
========================================================================
| <u:Object1> | "-7.7222223"^^<http://www.w3.org/2001/XMLSchema#float> |
| <u:Object2> | "0.0"^^<http://www.w3.org/2001/XMLSchema#float>        |
------------------------------------------------------------------------

7.10.15 Test19.java: Instantiate Oracle Database Using OracleConnection

Example 7-18 shows a different way to instantiate an Oracle object using a given OracleConnection object. (In a J2EE Web application, users can normally get an OracleConnection object from a J2EE data source.)

import java.io.*;
import com.hp.hpl.jena.query.*;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.util.FileManager;
import com.hp.hpl.jena.util.iterator.*;
import com.hp.hpl.jena.graph.*;
import com.hp.hpl.jena.update.*;
import oracle.spatial.rdf.client.jena.*;
import oracle.jdbc.pool.*;
import oracle.jdbc.*;
        
public class Test19 {
  public static void main(String[] args) throws Exception {
    String szJdbcURL = args[0];
    String szUser    = args[1];
    String szPasswd  = args[2];
    String szModelName = args[3];
 
    OracleDataSource ds = new OracleDataSource();
    ds.setURL(szJdbcURL);
    ds.setUser(szUser);
    ds.setPassword(szPasswd);
    OracleConnection conn = (OracleConnection) ds.getConnection();
    Oracle oracle = new Oracle(conn);
 
    ModelOracleSem model = ModelOracleSem.createOracleSemModel(oracle, 
szModelName);
    GraphOracleSem g = model.getGraph();
 
    g.add(Triple.create(Node.createURI("u:John"), Node.createURI("u:parentOf"), 
                        Node.createURI("u:Mary")));
    g.add(Triple.create(Node.createURI("u:John"), Node.createURI("u:parentOf"),   
                        Node.createURI("u:Jack")));
    g.add(Triple.create(Node.createURI("u:Mary"), Node.createURI("u:parentOf"), 
         Node.createURI("u:Jill")));
    String queryString =
       " SELECT ?s ?o  WHERE { ?s <u:parentOf> ?o .} ";
    Query query = QueryFactory.create(queryString) ;
    QueryExecution qexec = QueryExecutionFactory.create(query, model) ;
 
    ResultSet results = qexec.execSelect() ;
    ResultSetFormatter.out(System.out, results, query);
    qexec.close() ; 
    model.close();    
    OracleUtils.dropSemanticModel(oracle, szModelName);
    oracle.dispose();
  }
}

The following are the commands to compile and run Example 7-18, as well as the expected output of the java command.

javac -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:/slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar Test19.java
java -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:./slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar:./iri-0.8.jar:./icu4j-3.4.4.jar:./log4j-1.2.14.jar  Test19 jdbc:oracle:thin:@localhost:1521:orcl scott <password-for-scott> M1
-----------------------
| s        | o        |
=======================
| <u:John> | <u:Mary> |
| <u:John> | <u:Jack> |
| <u:Mary> | <u:Jill> |
-----------------------

7.10.16 Test20.java: Oracle Database Connection Pooling

Example 7-19 uses Oracle Database connection pooling.

import java.io.*;
import com.hp.hpl.jena.query.*;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.util.FileManager;
import com.hp.hpl.jena.util.iterator.*;
import com.hp.hpl.jena.graph.*;
import com.hp.hpl.jena.update.*;
import oracle.spatial.rdf.client.jena.*;
import oracle.jdbc.pool.*;
import oracle.jdbc.*;
 
public class Test20
{
  public static void main(String[] args) throws Exception
  {
    String szJdbcURL = args[0];
    String szUser    = args[1];
    String szPasswd  = args[2];
    String szModelName = args[3];
 
    // test with connection properties (taken from some example)
    java.util.Properties prop = new java.util.Properties();
    prop.setProperty("MinLimit", "2");     // the cache size is 2 at least 
    prop.setProperty("MaxLimit", "10");
    prop.setProperty("InitialLimit", "2"); // create 2 connections at startup
    prop.setProperty("InactivityTimeout", "1800");    //  seconds
    prop.setProperty("AbandonedConnectionTimeout", "900");  //  seconds
    prop.setProperty("MaxStatementsLimit", "10");
    prop.setProperty("PropertyCheckInterval", "60"); // seconds
 
    System.out.println("Creating OraclePool");
    OraclePool op = new OraclePool(szJdbcURL, szUser, szPasswd, prop, 
               "OracleSemConnPool");
    System.out.println("Done creating OraclePool");
 
    // grab an Oracle and do something with it
    System.out.println("Getting an Oracle from OraclePool");
    Oracle oracle = op.getOracle();
    System.out.println("Done");
    System.out.println("Is logical connection:" +
        oracle.getConnection().isLogicalConnection());
    GraphOracleSem g = new GraphOracleSem(oracle, szModelName);
    g.add(Triple.create(Node.createURI("u:John"), Node.createURI("u:parentOf"), 
                        Node.createURI("u:Mary")));
    g.close();
    // return the Oracle back to the pool
    oracle.dispose();
    
    // grab another Oracle and do something else 
    System.out.println("Getting an Oracle from OraclePool");
    oracle = op.getOracle();
    System.out.println("Done");
    System.out.println("Is logical connection:" +
        oracle.getConnection().isLogicalConnection());
    g = new GraphOracleSem(oracle, szModelName);
    g.add(Triple.create(Node.createURI("u:John"), Node.createURI("u:parentOf"), 
                        Node.createURI("u:Jack")));
    g.close();
    
    OracleUtils.dropSemanticModel(oracle, szModelName); 
    
    // return the Oracle back to the pool
    oracle.dispose();
  }
}

The following are the commands to compile and run Example 7-19, as well as the expected output of the java command.

javac -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:/slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar Test20.java
java -classpath ./:./jena-2.6.3.jar:./sdordfclient.jar:./ojdbc5.jar:./slf4j-api-1.5.8.jar:./slf4j-log4j12-1.5.8.jar:./arq-2.8.5.jar:./xercesImpl-2.7.1.jar:./iri-0.8.jar:./icu4j-3.4.4.jar:./log4j-1.2.14.jar  Test20 jdbc:oracle:thin:@localhost:1521:orcl scott <password-for-scott> M1
Creating OraclePool
Done creating OraclePool
Getting an Oracle from OraclePool
Done
Is logical connection:true
Getting an Oracle from OraclePool
Done
Is logical connection:true