Content Validation; Image Optimization - Comtech EF Data FX series 1005 Administrator's Manual

Comtech EF Data / Stampede

7.1.10 Content Validation

Guaranteed Object Freshness Time (seconds):
This setting determines the number of seconds that will elapse after storing an object in the client
browser cache before the object must be verified for freshness. If the value is set to 0 then objects are
verified every time the object is accessed. The default value is 10800 seconds (3 hours).
For Static Content:
The FX Series ADC optimizes data flow by keeping track of object expiration times. For native browsers, if
the object has not changed then a HTTP 304 Not Modified response is sent from the FX Series ADC
without requiring a round-trip between the FX Series ADC and the target web server. If the client browser
is engaged with the FX Series Remote, then this operation is performed at the FX Series Remote
eliminating round-trips between the browser and the FX Series ADC.
Override Expirations
This specifies whether the FX Series ADC should intelligently override the expiration date of an object
based on its heuristics. This feature reduces round trips by eliminating many unnecessary content
validation requests from the browser. Enabling this option for caching in some instances could produce
undesirable results. The default value is "Yes".
The object must be one of the content types specified in the "For the following content types:" field. A
comma separates each content type. The default value for this field is: "image/*, text/css, application/x-
Javascript, application/x-shockwave-flash, and

7.1.11 Image Optimization

JPEG Transformation
This function can lower the resolution of a JPEG in order to reduce communication bandwidth
requirements. The goal of the JPEG quality and smoothing values is to reduce the amount of data while
maintaining a usable image. The default settings (Quality=50, Smoothing=20) are reasonable settings for
most images and give a dramatic savings on the size of the jpeg images. The image is still very usable but
is not as crisp as the original. Depending on the jpeg, the compression is often in the range 9:1. If image
quality is paramount, setting Quality to 75 and Smoothing to 0, will still give some image size savings with
little if any loss of image integrity. There is a tradeoff between quality image compressions while still
yielding some savings of image sizes. The optimal setting is application dependent.
JPEG Quality
A number between 1 and 100 that specifies the tradeoff between size of the jpeg data and quality of the
original image. A higher number will retain a higher quality but will not conserve as much bandwidth.
The default value is 50.
The JPEG quality setting allows you to trade off compression against the quality of the reconstructed
image: the higher the quality setting, the larger the JPEG bandwidth requirements, and the closer the
output image will be to the original input.
JPEG Smoothing
A number between 1 and 100 that specifies the amount of dithering that will be used when generating
the image. A higher value indicates more dithering and somewhat less desirable image. The default value
is 20.
Minimum size threshold in K
This setting sets a minimum size of the JPEG file that is required for the JPEG optimization processing to
engage. The default size is 5K.
FX Series Administration Guide - Version 6.2.2
Chapter: FX Series Optimization Settings
Section: Application Policies Overview
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