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Manual Chapter: Using the Policy Editor
Manual Chapter
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From the Policy Editor screen, you can view the matching rules and acceleration rules for user-defined and predefined acceleration policies, as well as create or modify user-defined acceleration policies.
Policy Tree
Located on the left side of the Policy Editor screen, the Policy Tree contains branch nodes and leaf nodes. A branch node represents a group of content types (such as application generated or static) and each leaf node represents specific content (such as images, includes, PDF documents, or Word documents).

The Policy Tree function bar includes the following options:
Use to create a new content type group (branch node) or a new content type (leaf node).
Use to change the name of a branch or leaf node.
Use to remove a branch or leaf node.
Use to copy a branch or leaf node.
up, down arrows
Use to change the priority of a leaf node up or down within the branch node.
Screen trail
Located above the Policy Editor menu bar, the screen trail displays (horizontally) the screens that you accessed in order to arrive at the current screen. You can click the name of a screen in the trail to move back to a previous location.
Policy Editor menu bar
Located below the screen trail, the Policy Editor menu bar contains a list from which you select Matching Rules (default) or Acceleration Rules.
When you select Acceleration Rules, the acceleration rules menu bar displays, as illustrated in Figure 7.3.
Matching rules and acceleration rules for acceleration policies are organized on the Policy Tree, which you access from the Policy Editor screen.
The Application leaf node has two associated matching rules that identify a match for a CGI-based application as follows:
The Images leaf node has an associated matching rule that identifies a match in a request, if the file extension is .gif.
The WebAccelerator system matches requests to the Application leaf node when the requests path is for a CGI-based application. Since the WebAccelerator system matches both requests and responses, if the response from the application on the origin web server is a GIF image, the WebAccelerator system matches the response to the Images leaf node and applies that leafs associated acceleration rules.
The structure of the Policy Tree supports a parent-child relationship. This allows you to easily randomize rules. That is, because a leaf node in a Policy Tree inherits all the rules from its root node and branch node, you can quickly create multiple leaf nodes that contain the same rule parameters by creating a branch with multiple leaf nodes. If you override or create new rules at the branch node level, the WebAccelerator system reproduces those changes to the associated leaf nodes.
Root node
The root node exists only for the purpose of inheritance; the WebAccelerator system does not perform matching against root nodes. The Policy Tree typically has only one root node, from which all other nodes are created. For the example illustrated in Figure 7.5, the root node is Home. What distinguishes a root node from a branch node is that a root node has no parent node.
Branch node
The branch nodes exist only for the purpose of propagating rule parameters to leaf nodes; the WebAccelerator system does not perform matching against branch nodes. For the example illustrated in Figure 7.5, the branch nodes are Applications, Images, Documents, Components, and Other. Branch nodes can have multiple leaf (child) nodes, as well as child branch nodes.
Leaf node
A leaf node inherits rule parameters from its parent branch node. The WebAccelerator system performs matching only against leaf nodes, and then applies the leaf nodes corresponding acceleration rules to the request. Leaf nodes are displayed on the Policy Tree in order of priority. If a request matches two leaf nodes equally, the WebAccelerator system matches to the leaf node with the highest priority. For the example illustrated in Figure 7.5, the leaf nodes that are displaying are Default and Search.
Figure 7.5, shows a sample Policy Tree for an acceleration policy. Since the majority of the rules are the same for each leaf node, all of the example acceleration policys rule parameters are defined at the Home branch node. Therefore, all of the leaf nodes for the branch have the same matching and acceleration rules. From that point, it was easy to modify the rules only for the specific needs of the Default and Search leaf nodes.
When you create a user-defined acceleration policy by copying an existing acceleration policy, you must determine from which branch node the acceleration policy is inheriting specific rules, and decide whether you want to change the rules at the leaf node or change the rules at the branch node. To determine inheritance for a rule parameter, view the rule parameters inheritance icon.
For example, Figure 7.6 illustrates matching rules for the Path and Header rule parameters for a particular leaf node.
The arrow icon in the Inheritance column next to the Path parameter indicates this rule was inherited from the parent branch node. The inheritance icon next to the Header parameter does not have an arrow, indicating that the rule was not inherited; it was created locally at the leaf node.
Since the Header parameter rule is not inherited, you can delete the rule at the leaf node level. However, you cannot delete the Path parameter because it was inherited from the branch node. To delete the Path parameter rule, you must delete from its parent branch node.
For inherited rule parameters, you can determine the ancestor branch node by hovering the cursor over the inheritance icon. For this example, when placing the cursor on the inheritance icon next to Path, the branch node Home displays as the ancestor node, as illustrated in Figure 7.7.
When you override an inherited setting for a rule, an override icon displays (the inheritance icon with a red X) next to the rule setting. To see the node where the option was overridden, place your cursor over the override icon.
For example, for the content assembly rule in Figure 7.8, all of the options are inherited from the branch node, except for the Enable MultiConnect option. For this node, the rule was disabled at the leaf node. When hovering the cursor over the override icon, a message displays next to the Content Assembly Options menu.
To see if the current leaf node inherited this overridden option, click the parent branch node and view its rules. In Figure 7.9, you see that there were no rule settings overridden at the parent branch, indicating the rule was inherited from the branch node, Home, and overridden at the leaf node.
When you follow this rule back to its grandparent, you see the rule options are not inherited from any other node; they are set at the grandparent node and they are all enabled, as indicated in Figure 7.10.
Cancel the override setting at the parent, so that the parent inherits the Enable Content Compression setting of the grandparent, and passes that setting to the leaf node.
Keep in mind that if you cancel the override setting at the grandparent branch node, you change the settings for all of the child leaf nodes, not just the leaf node you want to change.
Tip: Although you have the option to override rules at the leaf node level, you should set up the Policy Tree in a logical way so that you only specify rules for branch nodes that you want all or most of its child leaf nodes to inherit. In other words, do not set a rule for a branch node if you know that most its leaf nodes will not use that rule.
To customize a user-defined acceleration policy, you can modify the branch and leaf nodes matching rules and acceleration rules. Or, you can add new branch and leaf nodes and associated matching and acceleration rules to the Policy Tree.
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