Is it possible in 4.x...

The documentation for v4.x iRules are in the product user manuals available on ask.f5.com. These code samples are from the following link

 

 

https://tech.f5.com/home/bigip/manuals/bigip4_6_2/bigip4_6_2ref/BIGip_rules.html1208927

 

Click here

 

 

 

rule my_rule { 
  if (tcp_content contains "XYZ") {
   use pool xyz_servers
  }
  else if (substr(tcp_content(100), 50, 3)) == "ABC" {
    use pool abc_servers
  }
  else {
    use pool web_servers
  }
}

 

 

rule my_rule { 
  if (http_content contains "ABC") { 
    use pool http_pool 
  } 
  else if (http_content_collected < 20) { 
    accumulate 
  } 
  else { 
    discard 
  } 
}

 

 

There are a couple of other examples in there but this should get you started.

 

 

-Joe