Mustache template action/transform

Hi Everyone,

I’m interesting in having the ability to render simple templates within OpenHAB rules, so that I can produce more complicated notification strings without lots of string concatenation. The Java port of Mustache ( looks to provide a nice simple engine that many people should already be familiar with.

My question is whether this should be implemented as a transformation or as an action. Superficially, a new transformation service makes some sense. However, the Actions development wiki page states:

So whenever you want to implement a complex functionality that is reusable and useful in many situations or if you need to access third-party Java libraries, implementing an action is the way to go.

Since I will need access to the mustache library this applies to me. Also, the use of a template transformation in an item (which would be enabled by implementation as a transformation service) doesn’t make much sense to me, since most complicated templates would require more than one item input to be useful.

What does the community think?