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Using PRTG placeholders in HTTP XML web server query



I want to check the status of an XML REST service which has the format: https://someservice.com/Messages?MessageDate=DD-MM-YYYY

Is it possible to substitute in a place-holder parameter with the current date? Otherwise, do you have any steps for setting up a custom sensor to achieve this?

http parameter prtg sensor xml

Created on May 8, 2013 10:05:48 AM

1 Reply



To answer my own question, after some googling, here is what I did:

1. Create a custom sensor and use batch file processing to create an environment variable with the correct format:

{{{call :prepare_date set datevalue=%yy%-%mm%-%dd%

REM Other stuff below...

:prepare_date for /f "tokens=1-4 delims=/-. " %%i in ('date /t') do (call :set_date %%i %%j %%k %%l) goto :eof

:set_date if "%1:0,1%" gtr "9" shift for /f "skip=1 tokens=2-4 delims=(-)" %%m in ('echo,^|date') do (set %%m=%1&set %%n=%2&set %%o=%3) goto :eof }}} 2. Using the WGET command line utility, I query the required web service. (http://www.gnu.org/software/wget/)

This is piped into the XmlStarlet command line utility which can return an element of an XML document based on a required Xpath query. (http://xmlstar.sourceforge.net/)

Thes utilities need to be available on he PATH to the custom sensor command file wget -q -O - "$@" "https://someservice.com/Messages?MessageDate>=%datevalue%" --no-check-certificate 2>nul | xml sel -t -v "//SomeData/@datavalue"

3. This command line is wrapped in the PRTG xml wrapper:

echo ^<?xml version="1.0" encoding="Windows-1252" ?^>
echo ^<prtg^>
echo    ^<result^>
echo        ^<channel^>SomeData^</channel^>
echo        ^<value^>
wget call here....
echo    ^</result^>
echo    ^<text^>OK^</text^>
echo ^</prtg^>

Created on May 13, 2013 9:44:11 AM

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