# Configuration parameters

Before defining additional instances, create a configuration parameter group (dhtParameterGroup) and a configuration parameter to use repeatedly with each instance. All instances are going to use the same messaging process instance (dhtDMServer) to communicate with each other. Create a configuration parameter associated with the dhtDMServer for use in all other instances. If changes are made to the messaging server instance, then only a single change in the instance reference is required rather than having to edit each of the process instances. In this sense, configuration parameters provide a way to add flexibility points in the system to make it more modular.

Create a configuration parameter group to hold the configuration parameter. In this system, only one configuration parameter will be created, but in a real system, there might be many more, so creating a group to hold them would be advantageous.

Right-click on the dhtPackage folder and select New parameter group from the context menu.

A dialog appears. Enter the following information into the dialog and click Add.

The parameter group editor appears. Click the Save button in the parameter group editor and the parameter group appears in the tree.

Right-click on the parameter group and select New Parameter Override.

A dialog appears. Enter the following information into the dialog and click Add.

The Parameter Editor appears at the bottom of the screen.

Associate the dhtDMServer process instance to the attribute values. Click the Add button at the top of the editor.

Type the process instance name into the dialog and click Add.

Click the Save button at the top of the editor.

The Package tree should look like this: