Curl Monitoring – Health Check of Web Page Using Curl

Yes, it's fully possible with curl. Most importantly will be to save and reload cookies between uses of curl with --cookie-jar. You can also post form data as needed. I usually use a Firefox add-on called Live HTTP Headers to capture what happens when I navigate a website. It will record any headers, but also any form posts which is very helpful when trying to figure out what to do with curl. I've written bash scripts automating various curl invocations and use pipes and temporary files (courtesy of mktemp) to do some limited processing on the webpage, but if have to do a lot of webpage processing I usually switch to Perl with LibWWW.

As @goldilocks suggested, taking out the double back slashes (\\) and replacing them with single backslashes (\) appears to fix your issue. Here's an example of the output with the modifications:

$ ./curl.bash 
<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <soap:Body>
    <CalcPrimeFactorsResponse xmlns="http://www.mathertel.de/S01_AsyncSamples/">
      <CalcPrimeFactorsResult>2 3 3 5 3607 3803</CalcPrimeFactorsResult>
    </CalcPrimeFactorsResponse>
  </soap:Body>
</soap:Envelope>

A better method?

curl provides the following construct which can be used to pass options into it:

#!/bin/bash

{ echo '--opt1'
  echo '--opt2'
  ...
} | curl --config -

So you could adapt the above like so:

#!/bin/bash

ENDPOINT="http://mathertel.de/AJAXEngine/S01_AsyncSamples/CalcService.asmx"
VALUE=1234567890

if [ -n "${1}" ]; then
    VALUE=${1}
fi

read -r -d '' DATA <<EOF
<?xml version="1.0" encoding="utf-8"?>
<soap12:Envelope 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
    xmlns:soap12="http://www.w3.org/2003/05/soap-envelope">
  <soap12:Body>
    <CalcPrimeFactors xmlns="http://www.mathertel.de/S01_AsyncSamples/">
      <inputText>${VALUE}</inputText>
    </CalcPrimeFactors>
  </soap12:Body>
</soap12:Envelope>
EOF

{
echo '--silent'
echo '--header "Content-Type: application/soap+xml; charset=utf-8"'
echo '--user-agent ""'
echo "--url ${ENDPOINT}"
echo '--data-binary @-'
echo "$DATA"
} | curl --config - | xmllint --format -

This construct makes it a little easier to parameterize the $DATA payloads so you could wrap the entire curl construct in a function and just pass it variables to include, for example.