Constants

Like variables, constants are used to represent data in a task. However constants have a fixed value and cannot be modified during a task's execution. The elements of a constant consists of a name and a value. When you use a constant in a task step, AutoMate BPA Server 7™ substitutes its assigned value when the task runs. Constants are defined globally for each machine, and once defined are available to all tasks on that machine.  

Uses for Constants

Constants are useful for data that may be different from machine to machine, or data that is used often and may change over time. Some examples would be user names, file locations, or e-mail addresses.  

For example, you could create a constant named ConstEmailNetAdmin and assign the network administrator's e-mail address as the value. You could use this constant in multiple tasks where you wanted to send an e-mail notification to the network administrator. If you wanted to run such a task at another location with a different network administrator, you would set up a constant of the same name at the other location and assign it whatever value you wanted. If the network administrator's e-mail address changed, you would simply change the value of the constant. The value entered will thereafter be used in all tasks containing that constant.

Naming Constants

To avoid conflicts with Basic key words, functions, or instruction, include distinguishing characters in the names of your constants. For example, you could start all constant names with CONST. Also, if you use many constants, you may want to use the names to categorize them. For example, you could begin all e-mail address constants with CONSTEMAIL and begin all file location constants with CONSTFILE.

Creating Constants

Constants can be created and defined from either the server or agent level which are located in two distinct locations within the SMC:

 

.Constants Properties

To create a constant from the Server or Agent properties:

  1. Click the New button. A new field becomes enabled allowing entry of the constant name, value and optionally, any comments regarding the constant.

  1. Enter the desired constant name under the Name parameter.

  2. Enter the constant's value in the Value parameter.

  3. Optionally, a customized description about the new constant can be entered in the Comments parameter. Any changes made are saved automatically. The newly created constant appears in the list of constants (disabled constants appear greyed out in the list of constants).

Other Operations

Parameters

Option

Description

Name

Enter the name of the constant.

Value

Enter the value of the constant.

Comment

Enter a comment.

 

Behavior

Constant behavior varies depending on where it was created from.

NOTE: All constants that appear grayed out specifies that the constant is disabled.

Using Constants

Constants may be used in any AutoMate BPA Server 7 step parameter by specifying the name of the constant surrounded by percent (%) signs. For example, if a constant named BackupFolder was initially created and given the value of an existing directory used to normally backup files to, in order to specify this directory as the destination in a 'Copy File' action, simply enter %BackupFolder% in the  Destination parameter of this action.

To add a constant in an action using the Expression Builder, follow the instructions below:

  1. From the properties dialog of an action, click inside any entry box then click the Insert Expression/Variable button which appear next to any entry box that accepts expressions.

  2. From the Expression Builder window that appears, select the folder labeled Constants from the list of folders located in the bottom left pane (as shown below).

  3. Double-click a selection from the list of the defined constants for the local machine that are populated in the bottom right pane. This populates the top pane with the selected item. The selected item will be automatically surrounded with percent signs upon insertion, therefore, there is no need to surround the item with percent signs at this point.

  4. Click the Insert button to properly insert the constant and close the Expression Builder window. For further information, see Expression Builder.

Expression Builder Window

Example

Machine 1 has Microsoft Office installed in C:\OFFICE. Machine 2 has Microsoft Office installed in D:\MSO

The task can be run on either machine and will find the correct file.

See Also

About Expressions

About Variables