Sectively compression for url using “*.uif”.

Question

Hi all,&nbsp;

&nbsp;
&nbsp;
I need help on writing iRule for selectively compressing as in the below. This is one of acceleration requirements from an liability insurance company for mobile T/F(migrating core insurance system for mobile users).&nbsp;
1)   Compress all HTTP responses except for compressed contents such as images.&nbsp;
2)   Selectively compress for url using “*.uif”.&nbsp;
     a)   If content-encoding of HTTP response is “gzip”, then no compression needed.&nbsp;
     b)   Compress all others.&nbsp;

&nbsp;
&nbsp;
My first answers:&nbsp;
Must set the Compression to "Selective" in the profile&nbsp;

&nbsp;
&nbsp;
rule selective_compress_enable {&nbsp;
   when HTTP_REQUEST {&nbsp;
        if { ([HTTP::uri] eq "*.uif") and ([HTTP::header value Content-Encoding] eq "gzip") } {&nbsp;
            log local0. "compression_rule_disable : *.uif &amp; gzip"&nbsp;
            COMPRESS::disable &nbsp;
        }&nbsp;
        else {&nbsp;
            COMPRESS::enable&nbsp;
        }&nbsp;
   }&nbsp;
}&nbsp;

&nbsp;
&nbsp;
I am very new to iRule and I'd like to have help on this.&nbsp;

&nbsp;
&nbsp;
Thanks in advance,&nbsp;

&nbsp;
&nbsp;
Neo&nbsp;

hoolio · Answer

Hi Neo, 
 I think you'll want to enable/disable compression in HTTP_RESPONSE based on the response content-type.  Though I'm not sure it makes sense to try to compress all content from the pool that's not already compressed.  I think you'd want to try to limit compression to content-types which can be compressed like text. 
 Also, do you want to enable or disable response compression for *.uif file requests?  It looks like UIF files might already be compressed ISO images. 
 As far as the HTTP profile setting, the COMPRESS::enable wiki page states the following: 
 http://devcentral.f5.com/wiki/default.aspx/iRules/COMPRESS__enable.html 
 Note that when using this command, you must set the HTTP profile setting Compression to Selective. 
 when HTTP_REQUEST {

Prevent response compression if request is for a uif filetype
   switch -glob [HTTP::path] {
      "*.uif" {
         set compress 0
      }
      default {
 set compress 1
      }
   }
}
when HTTP_RESPONSE {

Enable compression if request was not for a uif filetype,
    the response isn't already compressed and
    the response is text-based
   if {$compress and [HTTP::header Content-Encoding] ne "gzip" and [HTTP::header Content-Type] contains "text"}{
       COMPRESS::enable
   }
}
 
 Aaron

trx · Answer

Hello Aaron, 
&nbsp;    Why not just add a list of content types to the http profile when enabling compression? 
&nbsp;  
&nbsp; So what's the different between HTTP profile compression vs. IRules compression? 
&nbsp; If there is a difference, when would it make more sense to use one method over the other? 
&nbsp;  
&nbsp; Thoughts? 
&nbsp;  
&nbsp; Regards, 
&nbsp; TRX &nbsp;

hoolio · Answer

I guess you could do this with a custom HTTP profile.  The URI checks and content-types can be configured.  If the pool members use compression, you could prevent this by setting the Request Header To Erase to 'Accept-Encoding'.   This would be simpler and more efficient than an iRule. 
&nbsp;  
&nbsp; Aaron

trx · Answer

So it sounds like we would only need to enable IRule compression if we are trying to do complex logic compression, but if we are just compressing by the content types of static files we should just do it using HTTP Profiles at the Virtual Server Level. Aaron, when you say: 
&nbsp;  
&nbsp; "If the pool members use compression, you could prevent this by setting the Request Header To Erase to 'Accept-Encoding'",  
&nbsp;  
&nbsp; ... can you elaborate on what you mean by it? 
&nbsp;  
&nbsp; Regards, 
&nbsp; TRX

hoolio · Answer

So it sounds like we would only need to enable IRule compression if we are trying to do complex logic compression, but if we are just compressing by the content types of static files we should just do it using HTTP Profiles at the Virtual Server Level. 
&nbsp;  
&nbsp; Exactly. 
&nbsp;  
&nbsp; "If the pool members use compression, you could prevent this by setting the Request Header To Erase to 'Accept-Encoding'" 
&nbsp;  
&nbsp; You can set the HTTP profile to remove the Accept-Encoding header from HTTP requests sent to the pool.  This would indicate to the server that the client does not support compression of response payloads. 
&nbsp;  
&nbsp; Aaron

Forum Discussion

Sectively compression for url using “*.uif”.

F5 Container Ingress Services (CIS) and using k8s traffic policies to send traffic directly to pods

F5 Architecture Track Sessions - AppWorld 2026

Recent Discussions

OWA File Upload URIs for WAF Bypass

F5 AWAF/ASM learning only from Trusted traffic?

irule execution error

Curl 7.10.5 < 8.12.0 Integer Overflow (CVE-2025-0725)

Show or List F5 XC Routes in the Web

Related Content

How HTTP/2 Compression works under the hood

Selective Compression on BIG-IP

What is HTTP Part VIII - Compression and Caching

F5 iRules for HTTP compression profile

HTTP Profile WAN Optimized Compression

ABOUT DEVCENTRAL

RESOURCES

SUPPORT

PARTNERS