Even though wordpress uses PHP, I would like to build a web application within a wordpress site I already have, so that I don’t have to redo the site from scratch, and can use the same design elements I’ve already developed.
Is there a way to have certain pages on my existing wordpress site run Grails in the background, and then spit out the appropriate HTML elements so that it can use the existing buttons, divs, etc.?
Grails and PHP it totatlly different techologies. Grails is a framework written in and uses Groovy/Java, requires different web-server, etc.
Btw, there is another way: you can hide this two apps behind one frontend (nginx, or something), and map (proxy) different urls to different apps, some urls to wordpress, some to grails app.