Internal Variables

The Diameter > Mediation > Internal Variables page lists all of the Internal Variables that are configured in the system, and shows the Variable Name, Type, Default Value and Description available for each Rule Template. Internal variables represent buffers distinguished by the names and can store data of the specified format. The data stored in the buffers can be used both in the conditions and actions (via the Formatting Value Wizard screen) and it is accessible during the whole transaction.

Internal Variables are created by:

Setting the unique name.
Selecting the type for enabling syntax checks of the stored values.
Setting default value (optional). The default value is used in case the user does not provision/assign a new value to the variable. Note: It is also possible to leave the internal variable empty.
Writing a short description (optional) explaining what is the purpose of the variable and how it is used in the templates/rules.

After the new variable is created it becomes accessible on the Formatting Value Wizard. The user can provision/assign the value of the internal variable by means of newly introduced "Set Internal Variable" action. The internal variable is SET when:

The default value is provisioned and not overwritten by the action "Set Internal variable"
The action "Set Internal Variable" assigns a value to the internal variable
Any of the AVPs has matched the criteria and the option "Store matched instance into" has been chosen. The index number of the matched AVP is stored under the specified internal variable.

The value of the variable can be a static value, the value coming from the message, some previously stored value, etc. The next template can contain the condition which uses the previously provisioned internal variable. All newly created variables of integer types (both signed and unsigned) are accessible as AVP instance numbers on the Formatting Value Wizard screen. If the specified xl-value contains an internal variable ($name), the value of the variable set previously shall be used.