1 Introduction to XStream

This chapter introduces you to XStream, a new feature in Oracle Database 11g Release 2 (11.2). XStream enables information sharing with outstanding performance and usability.

This chapter contains the following topics:

About XStream

XStream consists of Oracle Database components and application programming interfaces (APIs) that enable client applications to receive data changes from an Oracle database and send data changes to an Oracle database. These data changes can be shared between Oracle databases and other systems. The other systems include non-Oracle databases, non-RDBMS Oracle products, file systems, third party software applications, and so on. A client application is designed by the user for specific purposes and use cases.

XStream consists of two major features: XStream Out and XStream In. XStream Out provides Oracle Database components and APIs that enable you to share data changes made to an Oracle database with other systems.

XStream In provides Oracle Database components and APIs that enable you to share data changes made to other systems with an Oracle database.

XStream is built on the infrastructure of Oracle Streams. Therefore, XStream inherits the flexibility and functionality of Oracle Streams, including:

  • The logical change record (LCR) format for streaming database changes

    An LCR is a message with a specific format that describes a database change. If the change was a data manipulation language (DML) operation, then a row LCR encapsulates each row change resulting from the DML operation. One DML operation might result in multiple row changes, and so one DML operation might result in multiple row LCRs. If the change was a data definition language (DDL) operation, then a single DDL LCR encapsulates the DDL change.

  • Filtering of database changes at the database level, schema level, table level, and row/column level

  • Rules and rule sets that control behavior, including inclusion and exclusion rules

  • Rule-based transformations that modify captured data changes

  • Support for the data types supported by Oracle Streams, including LOBs, LONG, LONG RAW, and XMLType

  • Customized configurations, including multiple inbound streams to a single database instance, multiple outbound streams from a single database instance, multiple outbound streams from a single capture process, and so on

  • Full-featured apply for XStream In, including apply parallelism for optimal performance, SQL generation, conflict detection and resolution, error handling, and customized apply with apply handlers

Note:

In both XStream Out and XStream In configurations, the client application must use a dedicated server connection.

Note:

When learning about and using XStream, a general knowledge of Oracle Streams concepts is helpful. See the following documents for conceptual information about Oracle Streams:

See Also:

Purpose of XStream

By using XStream, you can accomplish the following goals:

  • Replicate data changes

    Replication is generally used to improve availability and to improve performance by spreading the network load over multiple regions and servers. XStream enables you replicate data changes made to an Oracle database with other Oracle databases and with non-Oracle data sources.

  • Store data changes in files

    Some environments use files to store data changes for various reasons. For example, an environment might use files to store data changes if the environment does not have a physical network, if the environment uses disconnected computing, or if the environment uses satellite communications. After data changes are stored in files, the changes can be processed in any customized way by applications.

  • Share data changes with a client-side memory cache

    Some environments share data changes with a client-side memory cache to improve performance.

See Also:

Chapter 3, "XStream Use Cases"

Prerequisites for XStream

Using the XStream APIs requires purchasing a license for the Oracle GoldenGate product. See the documentation for the Oracle GoldenGate product for more information:

http://download.oracle.com/docs/cd/E15881_01/index.htm

In addition, this document assumes that you have the following skills:

Tasks and Tools for XStream

This section describes the common tasks you perform for XStream and the tools to use to complete the tasks.

This section contains the following topics:

XStream Tasks

The common tasks for XStream are the following:

  • Configure XStream

    Configuring XStream involves preparing an Oracle Database for XStream, creating the Oracle Database components used by XStream, and creating one or more client applications that communicate with the Oracle Database.

    See Chapter 4, "Configuring XStream" for information about this task.

  • Administer XStream

    Administering XStream involves managing the Oracle Database components used by XStream. It also involves managing the rules and rule sets used by these components. It might also require modifications to a client application.

    See Chapter 5, "Managing XStream" for information about this task.

  • Monitor XStream

    Monitoring XStream involves viewing Oracle Enterprise Manager pages related to XStream and querying data dictionary views related to XStream.

    See the Oracle Enterprise Manager online help and Chapter 6, "Monitoring XStream" for information about this task.

XStream Tools

Use the following tools to complete the tasks for XStream: