Converting JSON/XML string into alerting value!

Good morning all,

I appreciate this has been asked many many times, but I am really struggling to work through the excellent answers to find what it is I need to do. Essentially, we have a number of Custom REST sensors we'd like to deploy but face the age old issue that the most important result we need to monitor is a string. As such, I understand that I may need to convert this into a value for the purpose of monitoring for a change to said value. However, I am struggling with the creation of the custom rest template as well as how I then invoke the lookup file too I need to create.

My JSON looks like this:-

{"status":"UP","hazelcastHealthCheck":{"status":"UP","members":["10.18.16.193 (local: false)","10.18.16.194 (local: true)"]},"premcalcHealthCheck":{"status":"UP","url":"http://wl-osbsys-middle.group.net:8011/LifeProtPremCalc/proxy/LifeProtPremCalc?wsdl"},"diskSpace":{"status":"UP","total":1063256064,"free":877674496,"threshold":10485760},"db":{"status":"UP","olaLiveDataSource":{"status":"UP","database":"Microsoft SQL Server","hello":1},"secureOnlineAccessDataSource":{"status":"UP","database":"Microsoft SQL Server","hello":1},"climateDataSource":{"status":"UP","database":"Oracle","hello":1}},"hystrix":{"status":"UP"}}

We want to monitor select the node of say "premcalcHealthCheck" and then use the status result to monitor.

I have played around with some custom template formatting and so far it's been unseccesful. I would really appreciate it if someone could advise me how we can capture that string of 'UP' (or DOWN as the alternative) and then parse that as a numerical value to then alert if it goes from say '0' to '1' as a result.

Thank you in advance anyone who is able to help me and my inferior brain!!!!