Hmm, searching on Google for
JSON ESEL returns this actual forum topic, which was started two days ago, as a top 5 result. And the ESEL
project page on Freshmeat looks broken.
SoapUI does not support ESEL, but you can query/navigate JSON with XQuery or XPath since soapUI allows you to treat JSON responses as XML.
Here is an example on how to use XPath in soapUI.
SoapUI also let's you use any Java or Groovy (or JVM compatible) library through scripting. So you might be able to use ESEL inside soapUI if you find a library that supports ESEL.
Regards!
/Henrik
eviware.com