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Manual Chapter: Policy Management Guide for the BIG-IP WebAccelerator Module: 13 - Configuring Responses Cached Rules
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13

Configuring Responses Cached Rules


Managing responses cached rules

Most WebAccelerator system rules are based on information that is contained in a request. For example, when a particular query parameter is set to a certain value the WebAccelerator system performs a specified function. Or, that the presence or absence of a cookie prompts a specific response by the WebAccelerator system.

Response cached rules, on the other hand, are based on information contained in the response and provide the WebAccelerator system with the information it needs to determine if it should cache content.

Response cached rules provide the following benefits:

  • Providing content assurance.
  • Securely managing NTML-authorized content.

When you create a response cached rule, the WebAccelerator system evaluates the response that matches to the node for which the response cached rule is defined to determine whether it should cache the response.

Organizing the responses cached rules in the Request Type Hierarchy tree

You organize responses cached in the Request Type Hierarchy tree, with any associated responses cached rules assigned to the leaf node. The Request Type Hierarchy tree is described in Chapter 4, Introducing the Request Type Hierarchy Tree .

Each leaf node in the Request Type Hierarchy tree can have up to one responses cached rules defined for it. Responses cached rules are inherited from a parent node in their entirety. Unlike other types of caching rules where you can add to an inherited rule, you must override a response cached rule in its entirety at the parent node, when updating or modifying rules.

Defining responses cached rules

Responses cached rules are based on the following HTTP response characteristics:

  • Completeness of the response content.
  • Whether the response contains NTLM-authorized content.
  • Specific response status codes.

Determining the completeness of response content

The WebAccelerator system only caches content if it considers the content complete. The method that the WebAccelerator system uses to determine if content is complete is based on the type of data contained within the response. For example, for HTML pages the WebAccelerator system looks for beginning and ending HTML tags. For other type of content, the WebAccelerator system views the content-length or chunked encoding data.

By default the WebAccelerator system ensures that HTML pages are complete by requiring that HTML response pages contain both the beginning and ending HTML tags. You can override this behavior by allowing the WebAccelerator system to cache documents that do not contain matching begin and end HTML tags. If you override this default behavior, the WebAccelerator system uses information in the HTTP response headers to determine if the response is complete. For more information, see Caching responses .

To allow the WebAccelerator system to cache documents that do not contain matching begin and end HTML tags

  1. On the Main tab of the navigation pane, click Policies.
    The Policies screen opens, displaying a list of acceleration policies.
  2. Click Edit next to the acceleration policy that you want to edit.
    The Policy Editor screen opens.
  3. From the Request Type Hierarchy tree, click the node for which you want to modify the responses cached rule.
  4. On the acceleration policy menu bar, click Responses Cached. The Responses Cached rules screen opens.
  5. In the Caching Options area, clear the check box for Cache only if the document contains matching begin and end tags.
  6. Click the Save button.

Securely managing NTLM content

NTLM is a suite of authentication and session security protocols used in various Microsoft network protocol implementations and is widely used by the Microsoft NT family of products to safeguard sensitive information.

By default, the WebAccelerator does not cache content if it was requested over an NTLM connection. However, you can override this behavior so that the WebAccelerator system will store NTLM-authenticated content

To allow the WebAccelerator system to cache content received over an NTLM connection

  1. On the Main tab of the navigation pane, click Policies.
    The Policies screen opens, displaying a list of acceleration policies.
  2. Click Edit next to the acceleration policy that you want to edit.
    The Policy Editor screen opens.
  3. From the Request Type Hierarchy tree, click the node for which you want to modify the responses cached rule.
  4. On the acceleration policy menu bar, click Responses Cached.
    The Responses Cached rules screen opens.
  5. In the Caching Options area, check the box for Cache content received over NTLM-authenticated connection.
  6. Click the Save button.
  7. Log into the WebAccelerator system as root.
  8. Edit the pvsystem.conf file.
  9. Locate the <accelerateNTLM>false</accelerateNTLM> line and change it to true.
  10. Locate the <enableAutoNTLMAuth>false</enableAutoNTLMAuth> line and change it to true.
  11. Save and exit the pvsystem.conf file.
  12. Restart the WebAccelerator system processes, by typing the following command:
  13. bigstart restart pvac

Performing caching based on response codes

By default, the WebAccelerator system only caches content from the origin servers, if it contains the following HTTP response codes:

You can use responses cached rules to instruct the WebAccelerator system to cache responses for content that contains the response codes defined in Table 13.11 .

Table 13.11 Response codes
Response Code
Definition
300
Multiple Choices
301
Moved.
The requested content has been permanently assigned a new URI. The server is responding with a redirect to the new location for the content.
302
Found.
The requested content temporarily resides under a different URI. The redirect to the new location MIGHT change.
307
Temporary Redirect.
The requested content temporarily resides under a different URI. The redirect to the new location CAN change.
410
Gone.
The requested content is no longer available and a redirect is not available.

Configuring a responses cached rule example

This section of the chapter provides information about how to configure an example responses cached rule. For this example site, you have three top-level nodes in the Request Type Hierarchy tree as follows:

  • Home
    Specifies the rules related to the home page.
  • Applications
    Specifies the rules related to the applications for the site, with child nodes, such as:
    • Default
      Specifies the rules related to non-search related applications.
    • Search
      Specifies the rules related to your site's search application.
  • Images
    Specifies the rules related to graphics images.
Note

See, To create the Home, Application, and Images nodes for the example Request Type Hierarchy tree , located in Chapter 4, for specific instructions about how to create the Request Type Hierarchy tree.

For this example, your site had an application requested as http://www.somesite.com/apps/magic.jsp, but due to current development on your site, it is temporarily requested as http://www.somesite.com/apps/magicact.jsp.

As a result of this change, the WebAccelerator system handles requests for the http://www.somesite.com/apps/magic.jsp with a temporary redirect to http://www.somesite.com/apps/magicact.jsp.

For this example, add a response cached rule to the default node (which is inherited by all leaf nodes) that indicates that the WebAccelerator system should cache content that contains a 307 response code.

To create the responses cached policy for this example

  1. On the Main tab of the navigation pane, click Policies.
    The Policies screen opens, displaying a list of acceleration policies.
  2. Click Edit next to the acceleration policy that you want to edit.
    The Policy Editor screen opens.
  3. From the Request Type Hierarchy tree, click the Default node.
  4. On the acceleration policy menu bar, click Responses Cached. The Responses Cached rules screen opens.
  5. In the Response Codes Cached area, check the 307 - Temporary Redirect check box.
  6. Click the Save button.

For a new or modified acceleration policy to be in effect for your site, you must publish it. See Publishing acceleration policies , located in Chapter 3, for more information.




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