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Oracle Fusion Middleware Developer's Guide for Oracle TopLink
11g Release 1 (11.1.1)

Part Number B32441-03
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1 Introduction to TopLink

Oracle TopLink is an advanced, object-persistence and object-transformation framework that provides development tools and run-time capabilities that reduce development and maintenance efforts, and increase enterprise application functionality.

This chapter includes the following sections:

1.1 What Is TopLink?

Oracle TopLink builds high-performance applications that store persistent object-oriented data in a relational database. It successfully transforms object-oriented data into either relational data or Extensible Markup Language (XML) elements.

Figure 1-1 TopLink Runtime Architecture

TopLink Runtime Architecture
Description of "Figure 1-1 TopLink Runtime Architecture"

Using TopLink, you can integrate persistence and object-transformation into your application, while staying focused on your primary domain problem by taking advantage of an efficient, flexible, and field-proven solution (see Section 1.2, "What Is the Object-Persistence Impedance Mismatch").

TopLink is suitable for use with a wide range of Java 2 Enterprise Edition (Java EE) and Java application architectures (see Section 1.4, "TopLink Application Architectures"). Use TopLink to design, implement, deploy, and optimize an advanced, object-persistence and object-transformation layer that supports a variety of data sources and formats, including the following:

TopLink supports EJB 3.0 in Java EE and Java SE environments including integration with a variety of application servers, such as Oracle WebLogic Server, OC4J, SunAS, JBoss, and IBM WebSphere application server. TopLink also includes support for EJB 2.n container-managed persistence (CMP) in OC4J.

The extensive suite of development tools that TopLink provides, including Oracle JDeveloper TopLink Editor, Eclipse Dali, and Oracle TopLink Workbench, lets you quickly capture and define object-to-data source and object-to-data representation mappings in a flexible, efficient metadata format (see Section 2.9, "Working with TopLink Metadata").

The TopLink runtime lets your application exploit this mapping metadata with a simple session facade that provides in-depth support for data access, queries, transactions (both with and without an external transaction controller), and caching.

For more information about TopLink, see Section 1.3, "TopLink Key Features".

1.2 What Is the Object-Persistence Impedance Mismatch

Java-to-data source integration is a widely underestimated problem when creating enterprise Java applications. This complex problem involves more than simply reading from and writing to a data source. The data source elements include tables, rows, columns, and primary and foreign keys. The Java and Java EE include entity classes (regular Java classes or Enterprise JavaBeans (EJB) entity beans), business rules, complex relationships, and inheritance. In a nonrelational data source, you must match your Java entities with EIS records or XML elements and schemas. These differences (as shown in Figure 1-2) are known as the object-persistence impedance mismatch.

Figure 1-2 Solving Object-Persistence Impedance Mismatch

Description of Figure 1-2 follows
Description of "Figure 1-2 Solving Object-Persistence Impedance Mismatch"

Successful solution requires bridging these different technologies, and solving the object-persistence impedance mismatch–a challenging and resource-intensive problem. To solve this problem, you must resolve the following issues between Java EE and data source elements:

As an application developer, you need a product that lets integrate Java applications with any data source, without compromising ideal application design or data integrity. In addition, as a Java developer, you need the ability to store (that is, persist) and retrieve business domain objects using a relational database or a nonrelational data source as a repository.

TopLink Solution

TopLink addresses the disparity between Java objects and data sources. TopLink is a persistence framework that manages relational, object-relational data type, EIS, and XML mappings in a seamless manner. This lets you rapidly build applications that combine the best aspects of object technology and the specific data source. TopLink lets you do the following:

1.3 TopLink Key Features

TopLink provides an extensive and thorough set of features. You can use these features to rapidly build high-performance enterprise applications that are both scalable and maintainable.

Some of the primary features of TopLink are the following:

For additional information, see the TopLink page on OTN:

1.4 TopLink Application Architectures

You can use TopLink in a variety of application architectures, including three- and two-tier architectures, with or without Java EE, to access a variety of data types on both relational and nonrelational data sources.

Figure 1-3 TopLink and Your Application Architecture

Description of Figure 1-3 follows
Description of "Figure 1-3 TopLink and Your Application Architecture"

For more information on strategies for incorporating TopLink into your application architecture, see Section 2.2, "Designing Your Application with TopLink".

This section introduces some of the following common enterprise architectures used by TopLink applications: