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Manual Chapter: Managing Object Types
Manual Chapter
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Overview: Object classification

Before sending a response to a client, the BIG-IP system enters an informational X-WA-Info response header into the response to describe how it handled the response. You cannot change these informational headers, and they do not affect processing, however, they can provide useful information for evaluating the efficiency of your acceleration policies.

Part of the information included in the X-WA-Info response header is the object type. The BIG-IP system classifies, by object type and group, every response it receives from the origin web servers. The object type and group classification determine how the BIG-IP system handles compression for the response.

Classification by object type

To classify a response by object type, the BIG-IP reviews the response headers and classifies the responses based on the first information it finds. The following list defines the order for classification.

  • File extension in the Content-Disposition header’s file name field
  • File extension in the Content-Disposition header’s extension field
  • Content-Type header in the response, unless it is an ambiguous MIME type
  • Extension of the path in the request

For example, if the extension in the Content-Disposition header’s file name field is empty, then the BIG-IP looks at the Content-Disposition header’s extension field. If Content-Disposition header’s field has an extension, the BIG-IP checks to see if an object type is configured for the extension. If there is no match, it assigns an object type of other, and uses the object settings for other. The BIG-IP looks at the information in the Content-Type header only if there is no extension in the Content-Disposition header’s file name or extension fields.

Classification by group

In addition to classifying the response by object type, the BIG-IP also classifies the response by group.

For example, in the following X-WA-Info response header the object type (OT) is defined as Microsoft Word (msword) and the object group (OG) is documents.

X-WA-Info: [S10101.C30649.A28438.RA0.G0.U58517886].[OT/msword.OG/documents]

Management of object types

The BIG-IP offers two object types.

  • Pre-defined Object Types. The BIG-IP ships with several predefined object types, most of which are optimized for objects associated with specific applications.
  • User-defined Object Types. A user-defined object type is an object type that you create and for which you specify all of the parameters dictating how the BIG-IP manages the specified object type.

The Objects Types screen displays all of the object types that the BIG-IP system is currently applying to your acceleration policies. From the Object Types screen, you can view the object types that the BIG-IP is currently applying to acceleration policies, as well as access additional screens where you can perform the following tasks.

  • Create a user-defined object type.
  • View and modify the settings for an existing user-defined or predefined object type.
  • Delete a user-defined object type.
Note: You can delete only user-defined object types; you cannot delete predefined object types.

When you create a new object type or modify an existing object type, the BIG-IP system applies the object type changes globally to all acceleration policies.

When you modify a predefined object type and save it, an information icon displays next to the display name in the predefined object types table, indicating that the parameters for the object type are modified from the original version that was shipped with the BIG-IP device.

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