\begin{tikzpicture}[node distance=3em,nodes={rectangle,draw,minimum width=12em}]
% \node (0) [dotted] {Business layer};
% \node (1) [below=of 0] {Presentation layer};
\begin{tikzpicture}[node distance=3em,nodes={rectangle,draw,minimum width=12em}]
% \node (0) [dotted] {Business layer};
% \node (1) [below=of 0] {Presentation layer};