Not all applications will be suited to use the pre-defined WebAccelerator application acceleration policies without some modifications. This article is meant to assist in understanding the provided policy settings enough to use them as a base from which to start building a custom WebAccelerator application acceleration policy.

What is an Application Acceleration Policy?

A WebAccelerator application acceleration policy defines the conditions under which acceleration is desired (Matching Rules), and the type of acceleration which should take place (application acceleration behaviors).  Each of the pre-defined application acceleration  policies defines a specific set of rules and behaviors intended to meet that application’s specific requirements .

Matching Rules

The Matching Rules determine what types of content will be affected by the policy.  They are broken down by Path, then Content Type in a tree structure that can be observed under the left section of the WebAccelerator GUI when the Matching Rules dropdown is selected.  All application acceleration policies use the same 2 components to build Matching Rules: Path and Content Type.

Paths

The Path may be defined as “STARTS WITH /”, meaning that the entire site will match the policy, or any subset of the site may be referenced by using more specific path definitions.

Content Type

All policies use Content Type statements to further specify the various elements of the site to which specific acceleration behaviors may be applied.  For example, the Images category is defined as “MATCHES images.*”, meaning that the specified behavior would be applied to any response matching the “images” category as defined in the WebAccelerator's content-type map, which takes into consideration both extension and MIME type.

The breakdown of Content Types for all pre-defined application acceleration policies is as follows:

1.       The Site: defined by default as all Content Types anywhere under the root directory (/).

1.1.        Application Generated content

1.1.1.        HTML pages

1.1.2.        XML pages

1.2.         Static Content

1.2.1.        Images

1.2.2.        Includes (js and css objects)

1.2.3.        Various pre-defined document types ( .doc, .pdf, .xls, .txt, etc.)

1.2.4.        Media files

1.2.5.        Other binary files

1.3.        Unclassified objects – anything that doesn’t match any of the above selections

Hover your mouse over each category name link on the left to display a short list of the objects which match this category. For example, hovering over the "Images" category reveals that it is defined to include jpeg, gif, png, tiff, & bmp objects.

Configurable Application Acceleration Behaviors

The pre-defined policies differ in the association of the various acceleration behavior options to each of the Matching Rules. The full array of possible acceleration behaviors can be individually applied to each of the Matching Rule elements to customize WebAccelerator behavior for any application.

For each Matching Rule, there are 7 categories of acceleration behavior that may be changed.

Variationdefines which (if any) variations result in unique content. Use Variation if different versions of the content are required based on the specified variations in Host, Query Parameter, Cookie, Path Segment, User Agent, Client IP, etc, but the same acceleration is required. (Variation does not define whether different acceleration rules should apply to this content. If different acceleration is required based on these variations, then a new definition needs to be created specifiying the desired acceleration behavior.)

Assembly – defines whether to use WebAccelerator features such as Intelligent Browser Referencing, MultiConnect, Compression, and Content Assembly on Proxies on that Content Type.

Proxying – defines whether WebAccelerator will always get content for that Content Type from the origin servers.

Lifetime – defines how long to cache objects of that Content Type and whether or not to obey origin server caching information.

Invalidation – defines event triggers to force cached content to be refreshed before the defined expiration.

Connections – defines how to connect to the origin servers to retrieve that Content Type (ie, use separate connections or a pool).

Responses cached – defines which HTTP status codes to cache for that Content Type (ie, 200, 301, 302, 4xx, etc.)

WebAccelerator policies support different combinations of behaviors for each of these 7 options, which may then be applied to each Matching Rule, providing incredible granularity and flexibility.  Pre-defined application acceleration WebAccelerator policies have been developed to support both specific branded applications and a wide range of generic web applications.

Summary

The pre-defined application acceleration policies provided with WebAccelerator form a good base from which to build a WebAccelerator policy to meet the needs of any application.  The pre-defined policies provide base profiles of the typical functional differences in web applications, and may be leveraged to create custom user-defined policies with the desired behavior characteristics.  This knowledge of the possible combinations of configuration options as represented by the various WebAccelerator pre-defined policies makes it easier to choose the appropriate  policy base for your optimal custom WebAccelerator configuration.

 

(Note: This document discusses policies and configuration options present in WebAccelerator version 9.4.4.)

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