How Do You Interact with a Federated System?

You interface with a federated server exactly the same as you do with any other DB2 UDB. Typically, you interact with the federated system using one of these methods :

• Application programs

• The DB2 command line processor (CLP)

• The DB2 Command Center

• The DB2 Control Center

• Reporting tools

NOTE

The federated examples assume you are using the DB2 command line processor (CLP) or the DB2 Command Center to issue DB2 commands, unless otherwise noted.

The steps in the federated documentation specify which tasks can be performed through the Control Center. These steps provide the corresponding commands and SQL statements that can be entered in the DB2 CLP or the DB2 Command Center.

DB2 Command Line Processor (CLP)

You can perform all of the tasks necessary to set up, configure, tune, and maintain the federated system through the CLP. In some cases, the only way to perform certain tasks is to use either the DB2 CLP or the DB2 Command Center. For example:

• Modify wrapper options

• Create, alter, or drop user -defined data type mappings

• Create, alter, or drop user-defined function mappings

DB2 Command Center

Through the Command Center, you can create and run distributed requests without having to manually type out lengthy SQL statements. Use the Command Center when you are tuning the performance of the federated system. The Command Center is a convenient way to use the DB2 Explain functionality to look at the access plans for distributed requests. The Command Center can also be used to work with the SQL Assistant tool.

DB2 Control Center

The Control Center allows you to perform most of the tasks necessary to set up, configure, and modify the federated system. The Control Center uses panels ”dialog boxes and wizards ”to guide you through a task. These panels contain interactive help when your mouse hovers over a control such as a list box or command button. Additionally, each panel has a help button that provides information about the panel task and links to related concepts and reference information.

The Control Center is the easiest way to perform the essential data source configurations:

• Connect to the DB2 federated instance

• Create the wrappers

• Create the server definitions and server options

• Create the user mappings

• Create the nicknames

You can also use the Control Center to modify the data source configuration. You can alter or drop wrappers, server definitions, server options, user mappings, and nicknames.

Application Programs

Applications do not require any special coding to work with federated data. Applications access the system just like any other DB2 client application. Applications interface with the federated database that is within the federated server. To obtain data from data sources, they submit queries in DB2 SQL to the federated database. DB2 then distributes the queries to the appropriate data sources, collects the requested data, and returns this data to the applications. However, because DB2 interacts with the data sources through nicknames, you need to be aware of the following:

• The SQL restrictions when working with nicknames. For additional information, refer to the SQL Reference Guide.

• How to perform operations on nicknamed objects.