| Oracle® Objects for OLE C++ Class Library Developer's Guide 10g Release 2 (10.2) Part Number B14308-01 |
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| Oracle® Objects for OLE C++ Class Library Developer's Guide 10g Release 2 (10.2) Part Number B14308-01 |
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The OO4O operational hierarchy of the objects expresses has-a and belongs-to relationships.
The Automation Objects diagram illustrates this hierarchy.
The OSession object is returned when an instance of the OO4O Automation Server is created. It mainly serves as an interface for establishing connections to Oracle databases. It also contains methods for starting , committing, and canceling transactions on the connections contained in the OraDatabase objects that are created.
The ODatabase object represents a user connection to an Oracle database instance, and provides methods for execution of SQL commands and PL/SQL code. It is returned by the OpenDatabase method of the OSession or the OServer object.
An ODynaset object represents the result set of a SQL SELECT query or a PL/SQL cursor variable returned from a stored procedure or function. It is essentially a client-side scrollable and updatable cursor that allows for browsing the set of rows generated by the query it executes. It is created by the CreateDynaset or CreateCustomDynaset method of an ODatabase interface.
The OField object is an abstraction of a column in an OraDynaset. It contains the value as well the metadata that describes a column of the current row in the dynaset. OField objects can represent instances of any datatype supported by the Oracle database. This includes all primitive types, such as VARCHAR2, NUMBER, INT, and FLOAT, as well all the object/relational types introduced in Oracle8i. See Support for Oracle Datatypes.
The OMetaData object is returned by invoking the Describe method of the OraDatabase interface. The describe method takes the name of a schema object, such as the emp table, and returns an OraMetaData object. The OraMetaData object provides methods for dynamically navigating and accessing all the attributes (OMDAttribute collection) of a schema object described.
The OParameterCollection is a collection container for the OraParameter objects. An OraParameter object is used to supply data values for placeholders used in the SQL statements or PL/SQL blocks at run time. It can be used to provide input values as well as contain values that are returned from the server.
OParameter objects can contain values for all the datatypes supported by Oracle Database 10g including object/relational data types. They can be passed as input or output arguments to PL/SQL stored procedures and functions. The values of the OraParameter objects can also represent PL/SQL cursors in the form of ODynaset objects. See PL/SQL Supports.
An OParamArray object provides the mechanism for binding and fetching an array of values. It is typically used for performing bulk inserts and updates.
The OSqlStmt object is typically used for executing non-select SQL queries and PL/SQL blocks.
The OAQ Automation interface provides methods for enqueuing and dequeuing messages (OAQMsg). It also provides a method for monitoring queues for message arrivals. Client applications are notified when messages of interest are dequeued with the dispatch interface provided by client.
The OAQMsg object contains the message to be enqueued or dequeued. The message can be a raw message or any user-defined type.
The OAQAgent object represents a message recipient and is only valid for queues which allow multiple consumers. An OAQAgent object can be instantiated by invoking the AQAgent property of OAQMsg.
