Preface

This document provides the information required to build high performance applications. It also introduces the concepts with which you should be familiar to get the most out of Oracle Application Server TopLink.

This preface contains these topics:

Intended Audience

The Oracle Application Server TopLink Application Developer's Guide is intended for application developers creating Oracle Application Server TopLink applications.

This document assumes that you are familiar with the concepts of object-oriented programming, the Enterprise JavaBeans (EJB) specification, and your own particular Java development environment.

The document also assumes that you are familiar with your particular operating system (such as Windows, UNIX, or other). The general operation of any operating system is described in the user documentation for that system, and is not repeated in this manual.

Documentation Accessibility

Our goal is to make Oracle products, services, and supporting documentation accessible, with good usability, to the disabled community. To that end, our documentation includes features that make information available to users of assistive technology. This documentation is available in HTML format, and contains markup to facilitate access by the disabled community. Standards will continue to evolve over time, and Oracle Corporation is actively engaged with other market-leading technology vendors to address technical obstacles so that our documentation can be accessible to all of our customers. For additional information, visit the Oracle Accessibility Program Web site at

http://www.oracle.com/accessibility/

Accessibility of Code Examples in Documentation

JAWS, a Windows screen reader, may not always correctly read the code examples in this document. The conventions for writing code require that closing braces should appear on an otherwise empty line; however, JAWS may not always read a line of text that consists solely of a bracket or brace.

Accessibility of Links to External Web Sites in Documentation

This documentation may contain links to Web sites of other companies or organizations that Oracle Corporation does not own or control. Oracle Corporation neither evaluates nor makes any representations regarding the accessibility of these Web sites.

Organization

This document contains:

Chapter 1, "Understanding OracleAS TopLink"

This chapter contains general information on OracleAS TopLink. It discusses the OracleAS TopLink application space, development process, components, and the OracleAS TopLink metamodel.

Chapter 2, "OracleAS TopLink Architectures"

This chapter illustrates the five basic OracleAS TopLink architectures in use in projects all over the world.

Chapter 3, "Mapping"

This chapter contains information on creating mappings for your application. It includes discussions on the mapping features and functions you will use to build your project.

Chapter 4, "Sessions"

This chapter contains information on configuring and running sessions. It includes a discussion of the various types of session available in OracleAS TopLink, and the mechanisms and features OracleAS TopLink offers to customize and optimize your application at the session level.

Chapter 5, "Data Access"

This chapter describes how to access the data for your application. It includes discussions on database platforms and drivers, performance issues, and the OracleAS TopLink Software Development Kit (SDK).

Chapter 6, "Queries"

This chapter contains information on building and executing queries in an OracleAS TopLink application.

Chapter 7, "Transactions"

This chapter contains information on OracleAS TopLink transactions. It introduces the concepts of transactions and the OracleAS TopLink Unit of Work.

Chapter 8, "Cache"

This chapter contains information on the OracleAS TopLink cache, including discussions on cache isolation, cache synchronization, and other caching issues. It also introduces the concepts associated with running OracleAS TopLink in a clustered environment.

Chapter 9, "Packaging for Deployment"

This chapter contains information on packaging and deploying your OracleAS TopLink application.

Chapter 10, "Tuning for Performance"

This chapter contains information on optimizing your application for maximum efficiency and throughput.

Appendix A, "Application Development Tools"

This appendix contains information on the various tools included with OracleAS TopLink that help you get the most out of your application.

Appendix B, "Configuring OracleAS TopLink for J2EE Containers"

This appendix contains information on configuring OracleAS TopLink for use with J2EE containers.

Appendix C, "Error Codes and Messages"

This appendix contains information on exceptions and error codes you might encounter when building or running an OracleAS TopLink application.

Conventions

This section describes the conventions used in the text and code examples of this documentation set. It describes:

Conventions in Text

We use various conventions in text to help you more quickly identify special terms. The following table describes those conventions and provides examples of their use.

Convention	Meaning	Example
Italics	Italic typeface indicates book titles or emphasis.	Oracle9i Database Concepts Ensure that the recovery catalog and target database do not reside on the same disk.
`UPPERCASE monospace (fixed-width) font`	Uppercase monospace typeface indicates elements supplied by the system. Such elements include parameters, privileges, datatypes, RMAN keywords, SQL keywords, SQL*Plus or utility commands, packages and methods, as well as system-supplied column names, database objects and structures, usernames, and roles.	You can specify this clause only for a `NUMBER` column. You can back up the database by using the `BACKUP` command. Query the `TABLE_NAME` column in the `USER_TABLES` data dictionary view. Use the `DBMS_STATS`.`GENERATE_STATS` procedure.
`lowercase monospace (fixed-width) font`	Lowercase monospace typeface indicates executables, filenames, directory names, and sample user-supplied elements. Such elements include computer and database names, net service names, and connect identifiers, as well as user-supplied database objects and structures, column names, packages and classes, usernames and roles, program units, and parameter values. Note: Some programmatic elements use a mixture of UPPERCASE and lowercase. Enter these elements as shown.	Enter `sqlplus` to open SQL*Plus. The password is specified in the `orapwd` file. Back up the datafiles and control files in the `/disk1/oracle/dbs` directory. The `department_id`, `department_name`, and `location_id` columns are in the `hr.departments` table. Set the `QUERY_REWRITE_ENABLED` initialization parameter to `true.` Connect as `oe` user. The `JRepUtil` class implements these methods.
`lowercase italic monospace (fixed-width) font`	Lowercase italic monospace font represents placeholders or variables.	You can specify the `parallel_clause`. Run `U``old_release``.SQL` where `old_release` refers to the release you installed prior to upgrading.

Conventions in Code Examples

Code examples illustrate SQL, PL/SQL, SQL*Plus, or other command-line statements. They are displayed in a monospace (fixed-width) font and separated from normal text as shown in this example:

SELECT username FROM dba_users WHERE username = 'MIGRATE';

The following table describes typographic conventions used in code examples and provides examples of their use.

Convention	Meaning	Example
[ ]	Brackets enclose one or more optional items. Do not enter the brackets.	`DECIMAL (``digits` `[ ,` `precision` `])`
{ }	Braces enclose two or more items, one of which is required. Do not enter the braces.	`{ENABLE \| DISABLE}`
\|	A vertical bar represents a choice of two or more options within brackets or braces. Enter one of the options. Do not enter the vertical bar.	`{ENABLE \| DISABLE}` `[COMPRESS \| NOCOMPRESS]`
`...`	Horizontal ellipsis points indicate either: That we have omitted parts of the code that are not directly related to the example That you can repeat a portion of the code	`CREATE TABLE ... AS` `subquery``;` `SELECT` `col1``,` `col2``, ... ,` `coln` `FROM employees;`
. . .	Vertical ellipsis points indicate that we have omitted several lines of code not directly related to the example.
Other notation	You must enter symbols other than brackets, braces, vertical bars, and ellipsis points as shown.	`acctbal NUMBER(11,2);` `acct CONSTANT NUMBER(4) := 3;`
`Italics`	Italicized text indicates placeholders or variables for which you must supply particular values.	`CONNECT SYSTEM/``system_password` `DB_NAME =` `database_name`
`UPPERCASE`	Uppercase typeface indicates elements supplied by the system. We show these terms in uppercase in order to distinguish them from terms you define. Unless terms appear in brackets, enter them in the order and with the spelling shown. However, because these terms are not case sensitive, you can enter them in lowercase.	`SELECT last_name, employee_id FROM employees;` `SELECT * FROM USER_TABLES;` `DROP TABLE hr.employees;`
`lowercase`	Lowercase typeface indicates programmatic elements that you supply. For example, lowercase indicates names of tables, columns, or files. Note: Some programmatic elements use a mixture of UPPERCASE and lowercase. Enter these elements as shown.	`SELECT last_name, employee_id FROM employees;` `sqlplus hr/hr` `CREATE USER mjones IDENTIFIED BY ty3MU9;`