Using KAL to monitor app server behind CSS

Question

We have had issues in the past where the app server has crashed and the CSS would keep sending connections to the front end webserver.
I am trying to find a way to monitor/keepalive based on the availability of an app server. The webserver is acting as a database app server front end.
I would like to be able to use the CSS to send a fixed set of (form style or XML) input to the ASP webserver so that it will return an expected output (from the app server) that can be hashed. The GET hash comparison will tell the CSS that the app server is correctly responding to the input.
Any one have any experience with things like this?
Carl

Answer 1

Thanks Steve,
I created a script that I think will do what I want, but I am not really clear on a couple of points.
I could not find anything to expand on the syntax for the socket send command. I noticed that some scripts that were posted used what seems like a directive to use the GET method but did not include any input.
socket send ${SOCKET} "GET ${webpage} http1.0\n\n"
It seems there may be some undocumented arguments to the socket commands. How do I find them?
I need to send an XML query as if it came from a form so the webserver will return the webpage I expect it to. The script I have so far is;
! Filename: ap-kal-dbstat
! Parameters: None - must be coded in script
! Description:
! This script will attempt to connect to a web server
! front end to a database host and
! "GET" an html page with dynamic content. The "sendstring"
! is some XML query which should return an expected output.
! The script checks the contents of the page for the returnstring.
! If found, the script passes.
! Failure Upon:
! 1. The correct arguments are not supplied.
! 2. The CSS is unable to connect to the host.
! 3. The string is not found in the return page.
no echo
if ${ARGS}[#] "LT" "5"
echo "Usage: ap-kal-dbstat \'Hostname Port Page Sendstring Returnstring\'"
echo "Example: ap-kal-dbstat \'10.1.1.1 80 webpage.asp XML=string form-element\'"
exit script 1
endbranch
set host "${ARGS}[1]"
set port "${ARGS}[2]"
set page "${ARGS}[3]"
set sendstring "${ARGS}[4]"
set returnstring "${ARGS}[5]"
set EXIT_MSG "Host ${host} not responding on TCP port ${port}."
socket connect host ${host} port ${port} tcp session
set EXIT_MSG "Socket string: String sent."
socket send ${SOCKET} "GET ${webpage} ${sendstring}"
set EXIT_MSG "Socket->Waitfor returnstring not found or timed out waiting."
socket waitfor ${SOCKET} "${returnstring}" 500
set EXIT_MSG "Socket: disconnected"
socket disconnect ${SOCKET}
echo "String ${returnstring} was found."
no set EXIT_MSG
exit script 0
Does this look like it will achieve my objective?
Carl