System and method for exchanging data and commands between an object oriented system and relational system

A method for generating an object relational mapping data structure, the method comprising the steps of:

• determining whether an object relational mapping file has been specified;
• if an object relational mapping file has been specified, using an object relational mapping specification identified by the object relational mapping file as the identified object relational mapping specification;
• if an object relational mapping file has not been specified, determining an ORM identification name, retrieving an object relational mapping specification corresponding to the ORM identification name from a relational database, and using the retrieved object relational mapping specification as the identified object relational mapping specification;
• and
• creating an object relational mapping data structure using the identified object relational mapping specification.

A method for generating object relational mapping data structures from an object relational mapping specification includes the steps of:

• retrieving an object relational mapping specification;
• creating an instance of a plurality of data structures defining a mapping between an object model and a relational model;
• overriding default mappings using a SQL map specification;
• using additional specifications to create additional data structures;
• retrieving Metadata from a database to enhance the plurality of data structures;
• matching class information for object-oriented model with the plurality of data structures;
• generates SQL statements for each class;
• and
• generates inserts and update statements to apply SQL statements to the database.

A method for generating relational schema from an ORM specification and object class definitions, the method comprising the steps of:

• retrieving an object relational mapping specification;
• retrieving an object class definitions;
• creating an instance of a plurality of data structures defining a mapping between an object model and a relational model;
• overriding default mappings using a SQL map specification;
• using additional specifications to create additional data structures;
• and
• adding relational information to the data structures for each primitive and embedded attribute of the object-oriented model.

A method for generating an ORM specification and object class definitions from a database schema, the method comprising the steps of:

• generating object relational mapping data structures using an ORM template specification;
• performing at least one metadata query to retrieve information for the object relational mapping data structures;
• generating an object class definition using the object relational mapping data structures;
• and
• creating an ORM Specification using object relational mapping data structures.

A method for responding to an object call using a mapping unit, the method comprising the steps of:

• determining the type of object call;
• setting up an access plan data structure according to insert flags and insert details for accessing referenced objects;
• creating a command statement for accessing relational system;
• issuing the command statement on relational system;
• and
• processing the data from the relational system to provide it to the object-oriented system.

A method for responding to an object call using a mapping unit, the method comprising the steps of:

• determining the type of object call;
• setting up an access plan data structure according to flags settings;
• creating a command statement for accessing relational system by retrieving a base SELECT statement from ClassInfo, testing whether any predicate has been specified;
• and translating a specified predicate and appending the predicate as a WHERE clause, if a predicate has been specified;
• issuing the command statement on relational system, the command statement including the SELECT statement having a WHERE clause, if any, against a database of the relational system;
• and
• determining whether more rows are available from the database;
• if more rows are available from the database,
• fetching a next row and creating an instance of a top-level object;
• setting attribute values from corresponding column values;
• creating required foreign key entries and associating them with target class structures;
• determining whether there are query objects from the subclasses;
• and
• if there are additional query objects from the subclasses, repeat the steps of creating command statement for accessing relational system and issuing the command statement on relational system for the objects of subclasses.

A method for object streaming comprising the steps of:

• beginning a new transaction;
• generating a query call to a database exchange unit for a plurality of objects;
• returning the predetermined number (X) of objects;
• processing the returned objects;
• determining whether more objects are to be retrieved through the current stream of objects;
• retrieving and processing an additional number (m) of objects if more objects are to be retrieved through the current stream of objects;
• generating a query close to the database exchange unit;
• and
• committing the transaction to the database.