4-Tier Architecture

Tags: soft-eng

A useful architectural style for Object Oriented [see page 14, Systems].

It subdivides the middle tier of 3-tier architecture with business rules controlling cclasses used by this application only and business model modelling classes common to several applications. This is a good style for software reuse.

\begin{figure}
  \centering
  \begin{tikzpicture}[line/.style={very thick, dashed}]
    \begin{umlpackage}{User Interface}\end{umlpackage}
    \begin{umlpackage}[right=0.5cm of User Interface]{Business Rules}\end{umlpackage}
    \begin{umlpackage}[right=0.5cm of Business Rules]{Business Model}\end{umlpackage}
    \begin{umlpackage}[right=0.5cm of Business Model]{Persistent Storage}\end{umlpackage}

    \draw [line, dashed, ->, transform canvas={yshift=0.2cm}]  (User Interface) -- (Business Rules);
    \draw [line, dashed, <-, transform canvas={yshift=-0.2cm}] (User Interface) -- (Business Rules);
    \draw [line, dashed, ->, transform canvas={yshift=0.2cm}]  (Business Rules) -- (Business Model);
    \draw [line, dashed, <-, transform canvas={yshift=-0.2cm}] (Business Rules) -- (Business Model);
    \draw [line, dashed, ->, transform canvas={yshift=0.2cm}]  (Business Model) -- (Persistent Storage);
    \draw [line, dashed, <-, transform canvas={yshift=-0.2cm}] (Business Model) -- (Persistent Storage);
  \end{tikzpicture}
  \caption{4-Tier Architecture}
\end{figure}