External Variables

External variables are variables defined by a user in the environment where the TIBCO Operational Intelligence Hawk® RedTail - Container Edition agent runs.

First, you define the variable values in a variables file. Then you specify the variable file by using the -variable option when starting Hawk agent. The variables file should be placed in the container and the path to the external variable file should be configured in the environment variable variable. Then you can reference the external variable in a rulebase. For more information on agent startup parameters, see TIBCO® Operational Intelligence Hawk® RedTail Installation, Configuration, and Administration.

After variable values are defined and the properties file is specified to the agent, you can reference external variables in a rulebase by using the following syntax:

   ${External.<variable-name>}

where variable-name is the name of an environment variable defined in the properties file. The file uses a standard Java property file format, with one line per variable defined. Each entry is a name-value pair in the following format:

<variable-name>=<value>

You can reference external variables in string arguments of actions and in data source method string arguments. For example, the Hawk Services sample rulebase provides a rule for sending a high-level alert. Without variable substitution, the text of the alert is generic. With variable substitution, the alert includes information specific to the generating condition.