Fortinet 458 FortiWeb 5.0 Patch 6 Administration Guide
Based upon the HTTP Content-Type: headers that you select (which correspond to Internet
file type/MIME type categories such as images and XML), FortiWeb will compress matching
responses. The total size of a large web page with lengthy JavaScripts and CSS, while in transit,
could be many times smaller.
For example, a typical web page is comprised of several responses, such as an HTML
document:
Content-Type: text/html
perhaps several images:
Content-Type: image/png
and a JavaScript:
Content-Type: text/javascript
If your protected web servers do not already apply compression, and you configure a
compression policy for text/html and text/javascript, those typically lengthy and
repetitive text-based documents can be efficiently compressed into much smaller responses. If
bandwidth between server and client is the performance bottleneck, this could improve
performance dramatically.
Not all HTTP clients support compression: RPC clients, for example, transmit binary data and
do not support compression. For those host names and/or URLs, you should create exceptions.
To configure a file compression policy
1. Before you configure file compression, configure the exceptions, if any. See “Configuring
compression/decompression exemptions” on page 456.
2. Go to Application Delivery > Compression > File Compress Policy.
To access this part of the web UI, your administrator’s account access profile must have
Read and Write permission to items in the Web Protection Configuration category. For
details, see “Permissions” on page 47.
The maximum pre-compressed file size that FortiWeb can compress is 128 KB. Files larger than
that limit will be transmitted without compression.
If your web servers are already configured to compress responses, you should either disable
compression on the server, or configure exceptions for URLs hosted by that server. Otherwise,
in some cases, FortiWeb might expend resources compressing responses that have already
been compressed by the server. This can cause performance to decrease instead of increase.