Variables Exist
Component definition
This component checks all variables in a model to determine if they contain any value. If the variables have null value, the component exits through the "false" path. If the variables have value, the component exits through the "true" path.
This component can also expose any data that exists but lies outside the path of components that need to use it. It can see data anywhere in its model (even data from which it is not downstream) and make that data accessible on its own stream.
Component icon
Description of component output paths
Unknown
The component output paths are described in the following table:
Property |
Description |
true
|
Unknown
|
false
|
Unknown
|
Description of component tabs and their properties
The properties on the Configuration tab in the Variable Exist component are listed and described in the following table:
The properties on the Settings tab in the Variable Exist component are listed and described in the following table:
Connection information
Not applicable
Component settings
Unknown
Use cases
Here is an example use for the Variables Exist component:
Exception handling
Scenario: The amount of disk space gets too low on a server. An email is sent to the server administrator with a low disk space warning. If the email fails to send, the process follows the exception path and creates a log entry.
Process: This process is created as a Monitoring Project type.
The following screen shot shows the process:
A GetComputerInfo component checks a server and then it returns information to the process. A Number Range Rule component checks the remaining disk space and takes action if the disk space is low. Depending on how low the disk space is, one of two emails is sent to the server administrator.
If the emails fail, the server administrator has no way of knowing that the server is about to run out of disk space.
An Exception Trigger by Components component watches the email components for failure. If one fails, an exception is triggered and the workflow jumps to the exception component.
Before a log entry can be created, the Create Log Entry component needs to have access to process data from the GetComputerInfo component. Because the Create Log Entry component is not downstream from this component, it cannot see its data. The Variables Exist component makes this data available to the log components.
The following screen shot shows the editor for the Variables Exist component:
The variable ComputerInfo is checked. This variable is added to the data stream and used by the Create Log Entry component. The two lists that are seen here contain the same list of variables. The difference between the two lists: the list on the top treats selected variables as required variables, whereas the bottom list treats selected variables as optional variables. If any of the variables that are selected in the top list are not found, the component exits through the "false" path. If any of the variables that are selected in the bottom list are not found, the component exits through the "true" path, but only if all of the required variables (in the top list) are present. If you select only optional variables and none are found, the component exits through the "false" path.
The variable ComputerInfo is designated as a required variable. Also, the "Declare Variable Added If Exists" option is checked. If the variable is found to have value, the Variables Exist component exposes the data to all components after it.
If the Variables Exist component finds that ComputerInfo has value, it exits through the "true" outcome path into the first log component. If it finds that ComputerInfo has no value, it exits through the "false" outcome path into the second log component.
The following screen shot shows the first Create Log Entry editor:
These two screens are the Create Log Entry editor and its text editor. The log message contains process variables from the GetComputerInfo component, showing how much disk space remains on the server. The Variables Exist component provides these variables.
The second log component is configured exactly like this one, except that it does not include the variables.
Other components in this example are as follows:
The Variables Exist component can handle multiple variables. This component also lets you use variables as either required or optional. You can declare some variables optional. If only some of the variables exist, the component still uses the True outcome path.