I have a system with a frontend and a backend, which I separate by two different folders under the view folder, namely
view/frontend
view/admin
<s:link view="login.xhtml" value="Login"/>
<s:link view="/Admin/login.xhtml" value="Login"/>
login.xhtml isn't a valid view id in JSF. /Admin/login.xhtml is.
You can use EL here
<s:link view="#{basePath}/login.xhtml" />