Simple Rule ? (I think)

First, I think you want to test the http_host not the http_uri.

If there is a single substring which identifies the pool to select,

use a simple "contains" operator:

 
 rule myrule { 
    if (http_host contains "myweb") { 
       use pool pool1 
    } 
    else if (http_host contains "bobweb") { 
       use pool pool2 
    } 
    else { 
       use pool pool3 
    } 
 } 
 

On the other hand, if there are multiple substrings which identify the

pool to select, use a "contains one of" operator:

 
 class their_class { 
     "bobweb" 
     "danweb" 
 } 
 class our_class { 
     "yourweb" 
     "myweb" 
 } 
  
 rule myrule { 
    if (http_host contains one of our_class) { 
       use pool pool1 
    } 
    else if (http_host contains one of their_class) { 
       use pool pool2 
    } 
    else { 
       use pool pool3 
    } 
 }