If you are using Borland's Delphi or C++Builder to develop Oracle
applications, then the Direct Oracle Access component set can help
you to make a seamless integration between this great development
tool and database system. Not only will your application take
maximum advantage of both products, your application development
process will also benefit from the following key features:
High performance
Both online transaction and batch processing applications can
benefit from Oracle's performance features. Direct Oracle Access,
as the name suggests, directly accesses the Oracle Interface. This
guarantees optimal performance for standard database access
functions. Support for Array Fetching, Array DML, PL/SQL Blocks,
PL/SQL Tables, Local Statement Caching and the Direct Path Load
Engine enable you to optimize your application's performance
critical functions even more.
Easy application distribution
A Direct Oracle Access application does not require middleware
like the BDE or ODBC, it merely requires Oracle SQL*Net or Net8.
Consequently you can deploy your application without many of the
version dependency or configuration problems typically involved
with middleware installation.
Oracle Package support
Most PL/SQL code in Oracle databases is programmed in packages.
Direct Oracle Access provides a TOraclePackage component that
allows you to easily call packaged program units without detailed
declarations of these program units and their parameters.
Furthermore Direct Oracle Access includes a Package Wizard that
can generate classes to encapsulate the program units and record
types defined in packages. This will make your Oracle packages a
natural extension of the Object Pascal or C++ language.
TOracleDataSet
The dataset component in Direct Oracle Access supports Oracle
record locking, record refreshing, server generated values,
automatic sequence value generation, and BLOB compression.
Master/detail relations can automatically be setup if a foreign
key exists between the master and detail table or if the master
table contains one or more collection columns or attributes
(nested table or varray).
The TOracleDataSet can use much of the information in the Oracle
Dictionary at run time. Server Constraints can be checked on the
client, and constraint error messages can be read from a message
table. Format masks, range values and default values can also be
read from the dictionary. This allows you to create applications
with a minimum amount of 'database knowlegde' compiled into the
executable, dynamically adopting changes in the database without
even recompiling it.
Query By Example mode
The TOracleDataSet component has a Query By Example mode that
enables you to provide QBE Forms in your application without any
additional programming, and without any additional components or
controls. The resulting QBE queries are performed on the Oracle
Server, so that performance will be optimal and network traffic
will be minimal. The user can supply simple query values such as
JONES or 100, can include wildcard characters for string values
such as JON%, and can include comparison operators such as >, <,
NOT, BETWEEN, IN and so on.
Oracle Monitor
To monitor the database access activities of your Direct Oracle
Access application you can use the Oracle Monitor utility. It
displays the SQL, variables, timestamp, elapsed time, network
statistics, database statistics and query execution plan of each
activity. This can be helpful to find performance bottlenecks, for
tuning purposes, and to solve application errors.
Alert and Pipe events
The Oracle Server includes a dbms_alert and dbms_pipe package for
event processing. The TOracleEvent in Direct Oracle Access can
function as a receiver for these events. It works in a background
thread of your application, and can propagate database events to
the familiar object events. These events can occur synchronously
or asynchronously with the main thread of your application.
SQL scripts
If you need to execute many data definition language (DDL)
statements, for example to perform the database installation part
of your application, you can use the TOracleScript component. It
has a property editor that allows you to develop the script and
the individual commands. The extendible script language follows
the basic SQL*Plus syntax and supports all SQL statements. It also
supports substitution variables to make your scriptscustomizable.
Advanced Queueing
To take advantage of the Advanced Queuing option of Oracle8 you
can make use of the TOracleQueue component. The TOracleQueue
component encapsulates the basic functionality of the DBMS_AQ
package. It provides a convenient way to enqueue messages into a
queue or to dequeue messages from a queue. Messages can be
dequeued in a background thread of your application, and the
events that are generated in threaded mode can occur synchronously
or asynchronously with the main thread of your application.
Session Pooling
In server applications that frequently need to create sessions to
process requests from client applications, it may be useful to use
connection pooling. Without a pooling concept, each request could
lead to an actual database logon and logoff. By using the
TOracleSessionPool component, you can maintain a pool of database
sessions that can be used and reused for different requests. You
can define the minimum an maximum number of sessions in the pool,
define the TimeOut behavior for idle sessions in the pool, and
preset the username, password and database.
Support for Oracle specific features
Direct Oracle Access supports many Oracle specific features.
Besides the features mentioned above, it supports Oracle8 and
Oracle8i features like LOB Locators, Objects & References,
XMLTYPE, Timestamps, Scrollable Queries, Password Expiration,
External Procedure development, and the Oracle Services for MTS.
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