Oracle Objects for OLE in Oracle9i

Features Overview

September 2001

 

 

Product Summary

Oracle Objects for OLE (OO4O) is a COM-based database connectivity tool that combines seamless and optimized access to Oracle databases with easy to use interfaces. OO4O can be used in a variety of environments ranging from web applications to n-tier client/server applications. It can be used from virtually any programming or scripting language that supports the Microsoft COM Automation technology, such as Visual Basic, Active Server Pages, Visual C++, VBA in Excel, PowerBuilder, Delphi, Microsoft Internet Information Server, and COM+/Microsoft Transaction Server.

Because it is an Oracle native driver, OO4O provides fast performance on Windows clients to Oracle databases. It does not incur the overhead of ODBC and OLE DB drivers. OO4O has been developed and has evolved specifically for use with Oracle database servers. It provides easy access to features that are unique to Oracle, but are otherwise cumbersome or inaccessible to use from ODBC and OLE DB-based components, such as ADO.

Components

OO4O consists of an in-process COM Automation Server, a C++ class library, and the Oracle Data Control.

  • In-Process COM Automation Server: a set of COM Automation interfaces/objects for connecting to Oracle database servers, executing queries and managing the results.
  • C++ Class Library: a set of COM Automation interfaces/objects for connecting to Oracle database servers, executing queries and managing the results.
  • Oracle Data Control: an ActiveX Control that greatly simplifies the exchange of data between query results and popular data-aware visual controls, such as edit, list and grid controls. The Oracle Data Control supports virtually data-aware controls that can be bound to the Microsoft Data Control in Visual Basic.

Features

OO4O include the following major features:

  • Full support for PL/SQL, including seamless access to PL/SQL Cursors
  • Tunable client-side, scrollable and updateable cursors for easy and efficient access to result sets of any size
  • Support for array fetches, updates, and inserts resulting in reduced network roundtrips
  • Connection pooling to allow development of scalable mid-tier application components, such as IIS Active Server Pages that heavily use and serve dynamic content stored in Oracle database servers
  • Thread safety allowing safe access to automation objects in multithreaded environments
  • Small disk and memory footprint
  • Efficient management of database connections and user sessions (connection pooling and multiplexing)
  • Full support for COM+/Microsoft Transaction Server (MTS) coordinated transactions
  • Seamless access to instances of advanced Oracle data types:
    • Object References (REFs)
    • Object Instances (Objects)
    • Nested Tables
    • VARRAYs
    • BLOBs, CLOBs, NCLOBs and BFILEs
  • Easy to use interface for describing schema objects
  • Full support for accessing Advanced Queuing capabilities
  • Temporary LOBs support when calling stored procedures or functions that have LOB arguments
  • Asynchronous processing of PL/SQL and SQL
  • Application failover notification
  • Detection of Lost Connections
  • The Oracle Code Wizard for Stored Procedures, which automatically generates OO4O code that executes PL/SQL or Java stored procedures

Below are descriptions of some of the major features:

Support for Advanced Oracle Data Types

OO4O provides full support for accessing and manipulating instances of REFs, value instance, Variable-length arrays (VARRAYs), Nested tables, and LOBs.

Instances of these types can be fetched from the database or passed as input or output variables to SQL statements and PL/SQL blocks, including stored procedures and functions. All instances are mapped to COM Automation Interfaces that provide methods for dynamic attribute access and manipulation.

Support for COM+/Microsoft Transaction Server

COM+/MTS is essentially a COM-based TP-Monitor and relies on the Microsoft Distributed Transaction Coordinator (DTC) for distributed transaction support. Oracle database transactions initiated in OO4O automatically participate in global transactions coordinated by the MS DTC in MTS, provided that Oracle Services for MTS is installed and running. Database connections established in components deployed in MTS can also be pooled via the Oracle Services for MTS.

OO4O will use this API to provide the capability for enlisting user sessions contained in the OraDatabase Automation interface with DTC. All transactions on these user sessions are controlled by DTC after enlistment is completed. After an OraDatabase is enlisted with DTC, all local transactional operations for that object are disallowed.

Advanced Queuing Interface

OO4O provides interfaces for accessing the Advanced Queuing (AQ) feature in the Oracle database. It makes AQ accessible from popular COM-based development environments, such as Visual Basic.

The OraAQ Automation interface provides methods for enqueuing and dequeuing messages (OraAQMsg). It also provides a method for monitoring queues for message arrivals. Client applications are notified when messages of interest are dequeued via a callback object.

Connection Multiplexing

OO4O allows multiple user sessions to share a network connection to an Oracle Server. This capability is particularly useful for application components that use OO4O in n-tier distributed environments, such as a web environment.

Describing Schema Objects

OO4O includes interfaces for retrieving attributes of schema objects. Using the Describe method of the OraDatabase interface retrieves attributes. This method takes the name of a schema object (e.g. emp) and returns a COM Automation object (OraMetaData). OraMetaData provides methods for dynamically navigating and accessing all the attributes (OraMDAttribute collection) of a schema object described.

New Features in Oracle9i

XML Support

XML is quickly becoming one of the common data formats for Internet applications. In Oracle9i, OO4O introduces XML support, allowing users to easily extract and insert data from the Oracle database in XML format. OO4O users can now flexibly render XML from a dynaset object. The XML support includes the ability to use advanced data types and to control the XML output format.

Full Unicode Support

As more business applications become Internet-centric and globally accessible, the need to simplify application development in multiple written languages arises. Unicode is the universal character set standard that encodes all characters from languages worldwide. It provides the basis for global computing by allowing applications to be written once, then deployed in any and all languages.

OO4O and the Oracle9i database add this globalization support with full UCS2 Unicode support. Using Unicode in OO4O is transparent, requiring no application code changes. This makes developing global applications with OO4O easy and fast.

Enhanced Oracle Services for MTS

Many OO4O users employ MTS/COM+ for their transaction and object management. The Oracle Services for MTS acts as a proxy between the Oracle database and MTS/COM+ to perform these management tasks. The Oracle Services for MTS has been re-architected to improve the availability and scalability of OO4O applications using this application stack. The new architecture removes the single point of failure and bottlenecks that were present in previous versions. This redesign can be adopted transparently without having to make any application code changes.

Database Events

OO4O in Oracle9i includes support for publishing, detecting, and subscribing to database events. By allowing OO4O to publish and subscribe to events, Windows clients can interact closely with the Oracle database. This functionality allows server-side events to initiate client and middle-tier actions, and vice-versa.

This feature supports asynchronous notification of database events to interested subscribers. Under this model, the client can subscribe to one or more database events. Each database event that the client is interested in is stored as a subscription. When a database event of interest is triggered, the client subscriber's database event handler for that event is fired and the subscriber is notified. The database event subscriber is required to create a subscription, based on the database event of interest. At the time of subscription creation, the subscriber should provide an event handler. The database event handler should be an automation object that implements the NotifyDBEvents method. OO4O invokes the NotifyDBEvents method of the event handler when the particular database event is fired.

 

 

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