Abstract:
A method of processing a query in a system in an object oriented programming environment, includes using a code to create a condition filter in a standard query language statement, the condition filter defining properties to be satisfied by a result of the query, and the condition filter using an object to execute a precompiled query language statement, and sending the standard query language statement to a database.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an application programming interface (API), and more particularly, to an application programming interface with a tree structure to pass data values to a prepared statement object. 
   2. Discussion of the Related Art 
   A JDBC (Java Database Connectivity) provides connection for programs written in Java to the data in common databases. The JDBC permits encoding of access request statements in SQL (structured query language). The SELECT statement in the SQL statement includes 3 clauses—SELECT, FROM, and WHERE. 
   Conventionally, an API uses a string filter to create a SQL WHERE clause as a string and pass it to persistent object framework (POF). Then, in the persistent object framework, a JDBC Statement object is used to request a query to get the result data from a database. The Statement object is an object used for executing a simple SQL statement and obtaining the results produced by it. However, the Statement object needs to be compiled each time it is being used since it does not store the compiled results. 
   SUMMARY OF THE INVENTION 
   Accordingly, the present invention is directed to an application programming interface (API) that is an improvement of the related art. 
   Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
   To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a method of processing a query in a system in an object oriented programming environment, comprising:
         using a code to create a condition filter in a standard query language statement, the condition filter defining properties to be satisfied by a result of the query, and the condition filter using an object to execute a precompiled query language statement; and sending the standard query language statement to a database.       

   In another aspect of the present invention, a method of processing a query in a system in an object oriented programming environment, comprising: using an application programming interface (API) to create a standard query language (SQL) WHERE clause statement in a SQL statement and to pass the SQL WHERE clause statement to a persistent object framework (POF); and sending the SQL statement to a database, wherein the SQL WHERE clause statement includes a condition filter and uses a PreparedStatement object to request the query. 
   In another aspect of the present invention, an application programming interface (API) for a database query system in an object oriented programming environment, the application programming interface adapted to effect the steps comprising: creating a condition filter for a standard query language (SQL) WHERE clause statement; and passing the condition filter to a persistent object framework, wherein the SQL WHERE clause statement uses a PreparedStatement object to request a query. 
   In another aspect of the present invention, a computer program product comprising a computer useable medium having computer readable code embodied therein for a database query, the computer program product adapted to effect the steps comprising: making a connection with a database; using a code to create a condition filter in a standard query language statement, the condition filter defining properties to be satisfied by a result of the query, and the condition filter using an object to execute a precompiled query language statement; and sending the standard query language statement to the database. 
   In another aspect of the present invention, A computer program product comprising a computer useable medium having computer readable code embodied therein for a database query, the computer program product comprising: means for using a code to create a condition filter in a standard query language statement, means in the condition filter for defining properties to be satisfied by a result of the query, and means in the condition filter for using an object to execute a precompiled standard query language statement. 
   It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawing, which is included to provide further understanding of the invention and is incorporated in and constitutes a part of this specification, illustrates an embodiment of the invention and together with the description serves to explain the principles of the invention. In the drawing: 
     The  FIG. 1  is a block diagram showing database access with an interface according to the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Reference will now be made in detail to the preferred embodiment of the present invention, examples of which are illustrated in the accompanying drawings. 
   The FIGURE illustrates database access with the API (application programming interface) of the present invention. 
   The FIGURE shows a Java application, an API of the present invention, a database, and a JDBC for connecting the Java application to the database. The API of the present invention creates a condition filter for SQL WHERE clause statement that uses a JDBC PreparedStatement object in a persistent object framework (POF). The PreparedStatement object is an object that represents a precompiled SQL statement. The SQL statement is pre-compiled and stored in the PreparedStatement object. Thus, the PreparedStatement object can be used to efficiently execute the statement multiple times. The SQL statement contained in the PreparedStatement object can take one or more parameters as input arguments (IN parameters). The IN parameter is a parameter whose value is not specified when the SQL statement is created. The PreparedStatement object has a question mark (“?”) as a placeholder for each IN parameter. An application has to set a value for each question mark in a PreparedStatement object before executing the PreparedStatement. The PreparedStatement object has the potential to be more efficient than the Statement object because it has been pre-compiled and stored for future use. For that reason, a SQL statement that is executed many times may be created as a PreparedStatement object to increase efficiency. 
   The classes for the API of the present invention are described now. 
   CXPFilter class: This class is a base class to construct the condition filter for SQL WHERE clause to be used to create a JDBC PreparedStatement object. The data values in conditions will be replaced with ‘?’ and the corresponding data value list will also be created. The order of data values in the list is the same as the order of ‘?’ in the WHERE clause. Therefore, it is easy to use PreparedStatement.set( ) functions to set the data values. This class uses a tree data structure to store conditions internally. Following are characteristics of the CXPFilter:
         Types of condition operators: =, !=, &gt;, &lt;, &gt;=, &lt;=   Types of condition column values: String, Integer, Long, Boolean, BigDecimal, Date   Type of LIKE condition operation: LIKE   Types of null checking functions: IS NULL, IS NOT NULL   Types of case functions: UPPER, LOWER, INITCAP   TO_DATE function: TO_DATE   Types of logic operations: AND, OR   Formats of conditions:
           Normal condition:
               &lt;column_name&gt;condition_operator&lt;column_value&gt;   &lt;table_name.column_name&gt;condition_operator&lt;column_value&gt;   
               Like condition:
               &lt;column_name&gt;LIKE&lt;matching_pattern&gt;   &lt;table_name.column_name&gt;LIKE&lt;matching_pattern&gt;   
               Null checking condition:
               &lt;column_name&gt;IS NULL   &lt;table_name.column_name&gt;IS NULL   &lt;column_name&gt;IS NOT NULL   &lt;table_name.column_name&gt;IS NOT NULL   
               Case function condition:
               case_function(&lt;column_name&gt;) condition_operator case_function(&lt;column_value&gt;)   case_function(&lt;table_name.column_name&gt;) condition_operator case_function(&lt;column_value&gt;)   
               TO DATE function condition:
               &lt;column_name&gt;condition_operator TO_DATE (&lt;column_value&gt;, &lt;date_format&gt;)   &lt;table_name.column_name&gt;condition_operator TO_DATE(&lt;column value&gt;, &lt;date_format&gt;)   
               
           Class API:       

   
     
       
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
             
             
           
         
             
                 
                 
             
           
           
             
                 
               public class CXPFilter 
             
             
                 
               { 
             
             
                 
                      // Condition operators 
             
             
                 
                      static public final String COND_OPER_EQUAL = ″=″; 
             
             
                 
                      static public final String COND_OPER_NOT_EQUAL = ″! =″; 
             
             
                 
                      static public final String COND_OPER_GREAT = ″&gt;″; 
             
             
                 
                      static public final String COND_OPER_LESS = ″&lt;″; 
             
             
                 
                      static public final String COND_OPER_GREAT_EQUAL =″&gt;=″; 
             
             
                 
                      static public final String COND_OPER_LESS_EQUAL = ″&lt;=″; 
             
             
                 
                      //Null operators 
             
             
                 
                      static public final String NULL_OPER_NULL = ″IS NULL″; 
             
             
                 
                      static public final String COND_OPER_NOT_NULL = ″IS NOT 
             
             
                 
               NULL″; 
             
             
                 
                      //Logic operators 
             
             
                 
                      static public final String LOGIC_OPER_AND = ″AND″; 
             
             
                 
                      static public final String LOGIC_OPER_OR = ″OR″; 
             
             
                 
                      //Case function name 
             
             
                 
                      static public final String CASE_FUNCTION_LOWER = ″LOWER″; 
             
             
                 
                      static public final String CASE_FUNCTION_UPPER = ″UPPER″; 
             
             
                 
                      static public final String CASE_FUNCTION_INITCAP = ″INITCAP″; 
             
             
                 
                      public String getFilterStringForPreparedStmt ( ) throws CXException; 
             
           
        
         
             
                 
                   //Traverses the condition tree and return a filter string with 
             
             
                 
                   // ′?′ replacing the corresponding data values for WHERE 
             
             
                 
                   // clause for JDBC PreparedStatement object, 
             
           
        
         
             
                 
                      public string getFilterString ( ) throws CXException; 
             
           
        
         
             
                 
                   // Used for debugging only. It traverses the condition tree 
             
             
                 
                   // and return a filter string for WHERE clause. Comment the 
             
             
                 
                   // statement where calls this function after you finish 
             
             
                 
                   // debugging. Otherwise, it will impact the performance of the 
             
             
                 
                   // application. 
             
           
        
         
             
                 
                      public ArrayList getValueList ( ) throws CXException; 
             
           
        
         
             
                 
                   // Traverse the condition tree and return a data value list. 
             
             
                 
                   // The order of data values in the list is the same as the 
             
             
                 
                   // order of ′?′ in the WHERE clause. 
             
             
                 
               } 
             
             
                 
                 
             
           
        
       
     
   
   CXPNormalFilter class: The CXPNormalFilter is a derived class of the CXPFilter. This class constructs a normal condition filter for SQL WHERE clause to be used to create a JDBC PreparedStatement object. None of parameters in the CXPNormalFilter can be null. The characteristics of the CPXNormalFilter are as follows:
         Types of condition operator: =, !=, &gt;, &lt;,&gt;=, &lt;=   Types of condition column values: String, Integer, Long, Boolean, BigDecimal, Date   Format of condition:
           &lt;column_name&gt;operator&lt;column_value&gt;   &lt;table_name.column_name&gt;operator&lt;column_value&gt;   
           Class API:       

   
     
       
             
             
           
             
             
           
             
             
           
         
             
                 
                 
             
           
           
             
                 
                public class CXPNormalFilter extends CXPFilter 
             
             
                 
               { 
             
           
        
         
             
                 
               public CXPNormalFilter (String columnName, String operator, Object 
             
             
                 
               value) throws CXException; 
             
           
        
         
             
                 
               } 
             
             
                 
                 
             
           
        
       
     
       
       
         
           Note that none of the parameters can be “null ”. 
         
       
     
  
   CXPLikeFilter Class: The CXPLikeFilter is another derived class of the CXPFilter. This class constructs a LIKE condition filter for SQL WHERE clause to be used to create a JDBC PreparedStatement object. None of parameters in the CXPLikeFilter can be null. The characteristics of the CPXLikeFilter are as follows:
         Types of condition operators: LIKE   Types of condition column values: String   Format of condition:
           &lt;column_name&gt;LIKE&lt;matching_pattern&gt;   &lt;table_name.column_name&gt;LIKE&lt;matching_pattern&gt;   
           Class API:       

   
     
       
             
             
           
         
             
                 
                 
             
           
           
             
                 
               public class CXPLikeFilter extends CXPFilter 
             
             
                 
               { 
             
             
                 
                  public CXPLikeFilter (String, columnName, String pattern) 
             
             
                 
                  throws CXException; 
             
             
                 
               } 
             
             
                 
                 
             
           
        
       
     
       
       
         
           Note that none of the parameters can be “null”. 
         
       
     
  
   CXPIsNullFilter Class: The CXPIsNullFilter is another derived class of CXPFilter. This class constructs a IS NULL condition filter for SQL WHERE clause to be used to create a JDBC PreparedStatement object. None of parameters in the CXPIsNullFilter can be null. The characteristics of the CPXIsNullFilter are as follows:
         Types of IS NULL functions: IS NULL, IS NOT NULL   Format of condition:
           &lt;column_name&gt;IS NULL   &lt;table_name.column_name&gt;IS NULL   &lt;column_name&gt;IS NOT NULL   &lt;table_name.column_name&gt;IS NOT NULL   
           Class API:       

   
     
       
             
             
           
         
             
                 
                 
             
           
           
             
                 
               public class CXPIsNullFilter extends CXPFilter 
             
             
                 
               { 
             
             
                 
                      public CXPIsNulLFilter (String columnName, String operator) 
             
             
                 
                      throws CXException; 
             
             
                 
               } 
             
             
                 
                 
             
           
        
       
     
       
       
         
           Note that none of parameters can be “null ”. 
         
       
     
  
   CXPCaseFilter Class: The CXPCaseFilter is another derived class of CXPFilter. This class constructs a case condition filter for SQL WHERE clause to be used to create a JDBC PreparedStatement object. None of parameters in the CXPCaseFilter can be null. The characteristics of the CPXCaseFilter are as follows:
         Types of condition operators: =, !=,&gt;, &lt;, &gt;=, &lt;=   Types of case function: UPPER, LOWER, INITCAP   Types of condition column values: String   Format of condition:
           case_function(&lt;column_name&gt;) condition_operatorcase_function (&lt;column_value&gt;)   case_function(&lt;table_name.column_name&gt;) condition_operator case_function (&lt;column_value&gt;)   
           Class API:       

   
     
       
             
             
           
         
             
                 
                 
             
           
           
             
                 
               public class CXPCaseFilter extends CXPFilter 
             
             
                 
               { 
             
             
                 
                      public CXPCaseFilter (String, columnName, String operator, 
             
             
                 
                      String value, String caseFunc) throw CXException; 
             
             
                 
               } 
             
             
                 
                 
             
           
        
       
     
       
       
         
           Note that none of parameters can be “null ”. 
         
       
     
  
   CXPToDateFilter Class: The CXPToDateFilter is another derived class of CXPFilter. This class constructs a To_DATE condition filter for SQL WHERE clause to be used to create a JDBC PreparedStatement object. None of parameters in the CXPToDateFilter can be null. The characteristics of the CPXToDateFilter are as follows:
         Types of condition operators: =, !=, &gt;, &lt;, &gt;=, &lt;=   Types of condition values: String   Format of condition:
           &lt;column_name&gt;condition_operator TO_DATE (&lt;column_value&gt;,&lt;date_format&gt;)   &lt;table_name.column_name&gt;condition_operator TO DATE (&lt;column_value&gt;, &lt;date_format&gt;)   
           Class API:       

   
     
       
             
             
           
         
             
                 
                 
             
           
           
             
                 
               public class CXPToDateFilter extends CXPFilter 
             
             
                 
               { 
             
             
                 
                  public CXPToDateFilter (String columnName, String operator, 
             
             
                 
                  String dateStr, String dateFormat) throws CXException; 
             
             
                 
               } 
             
             
                 
                 
             
           
        
       
     
       
       
         
           Note that none of parameters can be “null ”. 
         
       
     
  
   CXPLogicFilter Class: The CXPLogicFilter is another derived class of CXPFilter. This class constructs a logic condition filter for SQL WHERE clause to be used to create a JDBC PreparedStatement object. The characteristics of the CXPLogicFilter are as follows:
         Types of logic operators: AND, OR   Format of condition: &lt;filter 1 &gt;logic_operator &lt;filter 2 &gt;   Class API:       

   
     
       
             
             
           
         
             
                 
                 
             
           
           
             
                 
               public class CXPLogicFilter extends CXPFilter 
             
             
                 
               { 
             
             
                 
                  public CXPLogicFilter (CXPFilter, filter1, String operator, 
             
             
                 
                  CXPFilter filter2) throws CXException; 
             
             
                 
               } 
             
             
                 
                 
             
           
        
       
     
   
   CXPQuery Class: The CXPQuery is also used in the API discussed as the related art. In the present invention, a line “void setFilter (CXPFilter, filter);” is added to the CXPQuery used in the API discussed as the related art. 
   Following are examples for using the API of the present invention. 
   EXAMPLE 1 
   Target
         Create a filter using all data value types: ((((employee.name=‘John’ OR employee.name=‘George’) AND (employee.age&lt;30 OR employee.birthday&gt;‘Jul. 17, 1971’)) AND (employee.salary&gt;100000 OR employee.bouns&gt;20000)) AND employee.married=0)       

   Code
         . . .   CXPContext context=CXRequestContext.getP 0 Context ( );   CXPQuery query=context.createQuery (“employee”);   . . .   String name 1 =“John”;   String name 2 =“George”   Integer age=new Integer (30);   Date birthday=new Date (“Jul. 17, 1971”);   Long salary=new Long (100000);   BigDecimal bonus=new BigDecimal (20000);   Boolean Married=new Boolean (false);   CXPFilter filter 1 =new CXPNormalFilter (“employee.name”, CXPFilter.COND_OPER_EQUAL, name 1 );   CXPFilter filter 2 =new CXPNormalFilter (“employee.name”, CXPFilter COND_OPER_EQUAL, name 2 )   CXPFilter filter 3 =new CXPLogicFilter (filter 1 , CXPFilter.LOGIC_OPER_OR, filter 2 );   filter 1 =new CXPNormalFilter (“employee.age”, CXPFilter.COND_OPER_LESS,age);   filter 2 =new CXPNormalFilter (“employee.birthday”, CXPFilter.COND_OPER_GREAT, birthday);   CXPFilterfilter 4 =new CXPLogicFilter (filter 1 , CXPFilter.LOGIC_OPER_OR, filter 2 );   CXPFilterfilter  5 =new CXPLogicFilter (filter 3 , CXPFilter.LOGIC_OPER_AND_, filter 4 );   filter 1 =new CXPNormalFilter (“employee.salary”, CXPFilter.COND_OPER_GREAT, salary);   filter 2 =new CXPNormalFilter (“employee bonus”, CXPFilter.COND_OPER_GREAT, bonus);   filter 3 =new CXPLogicFilter (filter 1 , CXPFilter.LOGIC_OPER_OR, filter 2 )   filter 4 =new CXPLogicFilter (filter 5 , CXPFilter.LOGIC_OPER_AND, filter 3 )   CXPFilter filter =new CXPLogicFilter (filter 4 , CXPFilter.LOGIC_OPER_AND, filter 1 );   System.out.println (“filter:”+filter.getFilterString ( )); // Remove it after debugging!!!   System.out.println (“filterPS:”+filter.getFilterStringForPreparedStmt ( )); // Remove it after debugging!!!   query.setFilter (filter);   query.begin ( );   . . .       

   Output
         filter ((((employee.name=‘John’ OR employee.name=‘George’) AND (employee.age&lt;30 OR employee.birthday&gt;‘Sat Jul 17 00:00:00 PDT 1971’)) AND (employee.salary&gt;100000 OR employee.bonus&gt;20000)) AND employee.married=0)   filterPS: ((((employee.name=? OR employee.name=?) AND (employee.age&lt;?OR employee.birthday&gt;?)) AND (employee.salary&gt;?OR employee.bonus&gt;?)) AND employee.married=?)       

   EXAMPLE 2 
   Target
         Use the new API with UPPER function in java.       

   Original Code
         . . .   CXPContext unitContext=CXRequestContext.getPOContext( );   CXPQuery query=unitContext.createQuery (“unit”);   query.setNativeFilter (“code=‘”+code+“’”+“and ((owner_handle=‘”+owner_id+“’)”+“OR (UPPER (owner_handle)=UPPER ‘system@0’)))”);   . . .   query.begin ( );   . . .       

   New Code
         . . .   CXPContext.unitContext=CXRequestContext.get.Context ( );   CXPQuery query =unitContext.createQuery (“unit”);   CXPFilter filter 1 =new CXPNormalFilter (“owner_handle”, CXPFilter.COND_OPER_EQUAL, owner_id);   CXPFilter filter 2 =new CXPCaseFilter (“owner_handle”, CXPFilter.COND_OPER_EQUAL, “system@ 0 ”, CXPFilter.CASE_FUNCTION_UPPER);   CXPFilter 3 filter 3 =new CXPLogicFilter (filter 1 , CXPFilter.LOGIC_OPER_OR, filter 2 );   filter 1 =new CXPNormalFilter (“code”, CXPFilter.COND_OPER_EQUAL, code);   filter 2 =new CXPLogicFilter (filter 1 , CXPFilter.LOGIC_OPER_AND, filer 3 );   System.out.println (“filterPS:”+filter 2 .getFilter.StringForPreparedStmt ( )); // Remove it after debugging!!!   query.setFilter (filter 2 );   . . .   query.begin ( );   . . .       

   Output
         (code=? AND (owner_handle=? OR UPPER (owner_handle)=UPPER (?)))       

   EXAMPLE 3 
   Target
         Use the new API with TO_DATE function in PriceList.getPriceListRows ( ) in actrasrc/modeles/oms 2 /com/netscape/oms 2 /pricing/PriceList.java.       

   Original Code
         . . .   CXPContext poContext=CXRequestContext.getPOContext ( );   CXPQuery query=poContext.createQuery (“price_list_row_view”);   . . .   Calendar cal=Calendar.getInstance ( );   String dateString=new SimpleDateFormat (“yyyy-MM-dd hh:mm:ss”) .format (cal.getTime ( ));   query.setNativeFilter (“price_list_header_id=+String.valueOf (headerId)+“AND is_active=”+String.valueOf (OMSData.DB_TRUE)+“AND NVL (effective_date, TO_DATE (‘0001-01-01 00:00:00’, ‘YYYY-MM-DD HH24:MI:SS’))”+“&lt;=TO_DATE(”‘+dateString +“’, ‘YYYY-MM-DD HH24:MI:SS’)”+“AND NVL (expiration_date, TO_DATE (‘4712-12-31 23:59:59’, ‘YYYY-MM-DD HH24:MI:SS’))”+“&gt;TO_DATE (”‘+dateString +“’, ‘YYYY-MM-DD HH24:MI:SS’)”+“AND pricing_identifier=‘”+pricingIdentifier+“’”);   query.begin ( );   . . .       

   New Code
         . . .   CXPContext poContext=CXREquestContext.getPOContext ( );   CXPQuery query=poContext.createQuery (“price list row_view”);   . . .   Calendar cal=Calendar.getInstance ( );   String dateString=new SimpleDateFormat (“yyyy-MM-dd hh:mm:ss”) .format (cal.getTime ( ));   Boolean isActive=new Boolean (true);   CXPFilter filter1=new CXPNormalFilter (price_list_header_id”, CXPFilter.COND_OPER_EQUAL, String.valueOf (headerId));   CXPFilter filter2=new CXPNormalFilter (“is_active”, CXPFilter.COND_OPER_EQUAL, isActive);   CXPFilter filter3=new CXPLogicFilter (filter1, CXPFilter.LOGIC_OPER_AND, filter2);   String column=“NVL (effective_date, TO_DATE (‘0001-01-0100:00:00’, ‘YYYY-MM-DD HH24:MI:SS’))”;   filter 1 =new CXPToDateFilter (column, “&lt;=”, date.String, “YYYY-MM-DD HH24:MI:SS”);   filter 2 =new CXPLogicFilter (filter 3 , CXPFilter.LOGIC_OPER_AND, filter 1 );   column=“NVL (expiration_date, TO_DATE (‘4712-12-3123:59:59’, ‘YYYY-MM-DD HH24:MI:SS’))”;   filter 1 =new CXPToDateFilter (column, “&gt;”, dateString, “YYYY-MM-DD HH24:MI:SS’);   filter 3 =new CXPLogicFilter (filter 2 , CXPFilter.LOGIC_OPER_AND, filter 1 )   filter 1 =new CXPNormalFilter (“pricing_identifier”, CXPFilter.COND_OPER_EQUAL, (pricingIdentifier);   filter 2 =new CXPLogicFilter (filter 3 , CXPFilter.LOGIC_OPER_AND, filter 1 )   System.out.println (“filterPS:”+filter 2 .getFilterStringForPreparedStmt ( )); // Remove it after debugging!!!   query.setFilter (filter 2 );   query.begin ( );   . . .       

   Output
         ((((price list_header_id=? AND is_active=?) AND NVL (effective_date, TO_DATE (‘0001-01-0100:00:00’, ‘YYYY-MM-DD HH24:MI:SS’))&lt;=   TO_DATE (?, ‘YYYY-MM-DDHH24:MI:SS’)) AND “NVL (expiration_date, TO_DATE (‘4712-12-3123:59:59’, ‘YYYY-MM-DD HH24:MI:SS’))&gt;   TO_DATE (? ‘YYYY-MM-DDHH24:MI:SS’)) AND pricing_identifier=?)       

   By using the API of the present invention, an application performance for database accessing can be improved since the PreparedStatement is used. Moreover, with the API of the present invention, different SQL WHERE clauses can be easily formed, thus a flexible JDBC can be provided. 
   It will be apparent to those skilled in the art that various modifications and variations can be made in the application programming interface (API) of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided that they come within the scope of any claims and their equivalents.