http insert or rewite request

The answer is yes. The question is how you want to do it. If you want the change to show up in the clients browser, then you will have to issue an HTTP::redirect

when HTTP_REQUEST {
  if { [HTTP::uri] eq "/test/Invtest" } {
    HTTP::redirect "http://[HTTP::host]/test1/inv/op/adapter_plain?namespace=urn%3Asite%2Ecom%3AAIT%3AInventoryCheck&interface=AITInventoryCheck_Abs"
  }
}

This will send a redirect request to the client brower and a new connection will be made to the new url.

But, if you just want to change what the backend web server sees and are not concerned that the client sees the change, you can just modify the HTTP::uri before sending it to the backend server

when HTTP_REQUEST {
  if { [HTTP::uri] eq "/test/Invtest" } {
    HTTP::uri "/test1/inv/op/adapter_plain?namespace=urn%3Asite%2Ecom%3AAIT%3AInventoryCheck&interface=AITInventoryCheck_Abs"
  }
}

Hope this helps...

-Joe