Rule Logic

A rule is made up of one or more filters that are used to determine whether a device complies with the rule. The Rule Construction dialog box begins with one empty filter. A device must match the entire filter list of a rule (as determined by the logical OR nd AND operators that are explained below) for the rule to apply to the device.

A filter is a row of fields providing a condition that must be met by a device in order for the bundle to be applied. For example, you can add a filter to specify that the device must have exactly 512 MB of RAM in order to be accepted by the rule, and you can add another filter to specify that the hard drive be at least 20 GB in size. There is no technical limit to the number of filters that you can add in the rule, but there are practical limits, such as:

Designing a rule that is easy to understand
Devising the rule so that you do not accidentally create conflicting filters
Being able to view the dialog box as it grows in size because of the filters and filter sets that you add

Filters can be added individually or in sets. Each set contains logical operators within the set and logical operators determine the association between the sets.

By default, the logical operator AND is displayed for the filters within a set in the Combine Filters Using field (which you can change), and OR is displayed in the Filter Sets Will Be Combined Using field (display-only). If you change the Combine Filters Using field to OR, the Filter Sets Will Be Combined Using field then displays AND.

You can think of filters and filter sets as using algebraic notation parentheticals, where filters are contained within parentheses, and sets are separated into a series of parenthetical groups. Logical operators (AND and OR) separate the filters within the parentheses, and the operators are used to separate the parentheticals.

For example, “(u AND v AND w) OR (x AND y AND z)” means “match either uvw or xyz.” In the Rule Construction dialog box, it looks like this:

u AND

v AND

OR

x AND

y AND

Filter sets cannot be nested. You can only enter them in series, and the first filter set to match the device (the default of OR) is used to validate the rule so that the bundle can be applied to do imaging work on the device.

The order in which filters and filter sets are listed does not matter. For the OR operator, the first to be met satisfies the rule. For the AND operator, all items must be met to satisfy the rule.

HINT:You can easily run a test to see how these logical operators work. Access the Rule Construction dialog box, click both the Add Filter and Add Filter Set options a few times each to create a few filter sets, then switch between AND and OR in the Combine Filters Using field and observe how the operators change. Then, either select the filters that you added and click Delete, or click Cancel to exit the Rule Construction dialog box.

You can set up the conditions for a rule by adding all of the filters and filter sets that you need to identify the type of device you want to match. You typically do not need to set up complex rules. However, because you can apply multiple rules to a bundle, you can further complicate the use of logical operators, because each rule is considered to be an OR condition for the bundle, causing the bundle to be applied if any one of the rules matches the device.

For example, you could create several rules for the bundle with each rule being a long listing of AND conditions to be met. This means that each rule becomes a specific set of criteria for a device to meet, causing the bundle to be applied if one is met. Conversely, if you add that same amount of information into one rule (using filter sets for the AND and OR conditions), it might make the dialog box so long that it becomes unmanageable.

To determine what you need, consider the following possibilities:

One filter set with multiple filters
Multiple filter sets with only one or a few filters per set
Multiple filter sets each with multiple filters
Multiple rules per bundle

Remember that the logical operators for filters within a set are the opposite of the operators between the sets, and all rules for a bundle use the OR condition. For example, suppose you are selecting the operator in the Combine Filters Using field:

Operator	Within Filter Sets	Between Filter Sets	Multiple Rules Per Bundle
OR	Only one filter in the set needs to apply to the device (OR condition). The first filter that applies is used.	Each filter set must have one filter in it that applies to the device (AND condition).	The first rule that applies is used (OR condition).
AND	All filters within the set must apply to the device (AND condition).	Only one filter in the set must apply to the device (OR condition). The first filter that applies is used.	The first rule that applies is used (OR condition).

Obviously, adding filter sets complicates the use of logical operators, and adding multiple rules to the bundle further complicates it. Therefore, carefully plan how to configure your information before using the Rules Configuration dialog box.