Using Powershell to create an iApp Service

Got some inspiration from this https://devcentral.f5.com/Forums/tabid/53/afv/topic/aff/5/aft/2161558/Default.aspx So I tested by removing some TCP::collect from the irules. The delayed response problem disappeared after I commented the TCP::collect in rules handling SERVER_CONNECTED event. However I realized it was not message-based load balancing but connection based load balancing. I did add "mblb" profile to the virtual server. Obviously the irules I wrote to extract individual messages didn't work. But why?

 

 

 

Can someone explain to me when I should use TCP::collect? I found some examples call TCP::collect almost in every event declaration, which I don't understand. I personally think I only need to call it in CLIENT_ACCEPTED and CLIENT_DATA.

 

 

 

Below are my current irules:

 

 

 

when CLIENT_ACCEPTED {

 

set client_closed 0

 

TCP::collect

 

}

 

 

 

periodically checks if the client connection closed, if so, also closes associated server connection.

 

when CLIENT_CLOSED {

 

set client_closed 1

 

}

 

 

 

Triggered when a connection has been established with the target node

 

when SERVER_CONNECTED {

 

after 1000 -periodic if {$client_closed} {TCP::close}

 

TCP::collect

 

}

 

 

 

when CLIENT_DATA {

 

binary scan [TCP::payload] II head rlen

 

if {($head & 0x3) == 1} {

 

if {[TCP::payload length] < [expr {8 + $rlen}]} {

 

TCP::collect [expr {$rlen + 8 - [TCP::payload length]}]

 

return

 

}

 

}

 

 

TCP::release [expr {$rlen + 8}]

 

TCP::notify request

 

TCP::collect

 

}

 

 

 

when USER_REQUEST {

 

pool my_pool

 

}

 

 

 

Hi Shu,

 

 

The TCP::collect event occurs prior to the CLIENT_DATA or SERVER_DATA events.

 

 

The Wiki page for TCP::collect should help determine when/if to utilize it and how.

 

 

Hope this helps.

Hi Shu,

 

 

when mblb profile is used, USER_REQUEST event will not be fired.

 

you may try moving pool command to CLIENT_DATA (above the TCP::release)

 

 

Nat

Thanks, Nat! You made my day. Moving pool command to CLIENT_DATA is the right solution. Unfortunately, I couldn't find this on the documents I've read so far and F5 support didn't even want to look at the simple irules I wrote.

 

 

Thank you Michael too. I think what you said is a general principle to use TCP::collect. For MBLB, one may have to call TCP::collect in CLIENT_DATA to extract single messages.

 

 

Hi Shu, the correct iRule would it?

when CLIENT_ACCEPTED {

set client_closed 0 TCP::collect

}

when CLIENT_CLOSED {

set client_closed 1

}

when SERVER_CONNECTED { after 1000 -periodic if {$client_closed} {TCP::close} }

when CLIENT_DATA {

binary scan [TCP::payload] II head rlen

if {($head & 0x3) == 1} {

if {[TCP::payload length] < [expr {8 + $rlen}]} {

    TCP::collect [expr {$rlen + 8 - [TCP::payload length]}]

    return

}

}

pool my_pool

TCP::release [expr {$rlen + 8}]

TCP::notify request

TCP::collect

}