Having the REST application set up, or having the index.html file displaying application under CSP Files directory, is it even possible to set this WEB application as a default one for the server?
In other words, how to display the application by querying http://localhost, but not http://localhost/AppName/ or http://localhost/index.html?
On
If you want to achieve it with internal Apache, you just only need to create root WebApplication in Caché. As well as I'm sure you already did it before like /AppName/, just create with name /.
If you want to do it with external Apache, then I hope you already have properly configured one. Just what you need then, is to add such lines
<Location />
CSP on
SetHandler csp-handler-sa
</Location>
In you REST class, you must be already know, that Route map uses regexp to get correct method. So, in routes map you can change it so
<Routes>
<Route Url="/(index\.html)?" Method="GET" Call="Index"/>
<!-- or something like this, to catch all static for one method -->
<Route Url="/((?!rest/).*)" Method="GET" Call="GetStatic"/>
...
</Routes>
Having the RESTful application, you need to name your WEB-application as '/', and create the route with the same name inside the dispatch class:
<Routes>
<Route Url="/" Method="GET" Call="Index"/>
...
</Routes>
...and then implement the Index method as you desire.
In case of the index.html file - I believe that there is someone other who know the solution.
Your best bet is likely to setup routing rules in the Apache server that is started with the instance.