How do I layer nodes/boxes in a drawing?

Question

I'm trying to make a diagram that shows relations of elements in a system, but I don't know how to layer anything.

So far I've got:

\documentclass{book}
\usepackage{tikz}
\usetikzlibrary{shapes,arrows,positioning}

\begin{document}

\tikzstyle{narrow} = [draw, fill=blue!20, text width=2cm, text centered, minimum height=1cm]
\tikzstyle{wide}   = [draw, fill=orange!20, text width=7.5cm, text centered, minimum height=1.75cm, rounded corners]
\tikzstyle{tall}   = [draw, fill=green!20, text width=1.75cm, text centered, minimum height=7cm, rounded corners]
\tikzstyle{squar} = [draw, fill=yellow!10, text width=4.75cm, text centered, minimum height=3.75cm, rounded corners]

\def\blockdist{5}
\def\edgedist{5}

\begin{tikzpicture}
  \node (lib)     [tall]   {Library};
  \node at (3,-1) (tman)    [narrow] {tmon};
  \node (ksman)   [narrow] [right=.75cm of tman]   {ksmon};
  \node (stsp)    [narrow] [right=.75cm of ksman]  {stosp};
  \node (deamon)  [wide]   [below=.75cm of ksman]  {base};
  \node (imgan)   [narrow] [above=.75cm of tman]   {img-analysis};
  \node (thrman)  [narrow] [above=.75cm of imgan]  {thermal-analysis};
  \node (scrpts)  [squar]  [right=.75cm of thrman] {Scripts};
\end{tikzpicture}

\end{document}

There are three things I'm trying to accomplish:

1. How can I put a box around/behind the "ksmon" and "stosp" nodes?
2. How can I put a box around/behind the one created above and the "tmon" node?
3. How can I put nodes in/on top of the "Scripts" nodes?

Answer 1

I don't really know where you had your problems …
If you really want the boxes that go behind tmon, ksmon and stosp to be drawn after the nodes you can use PGF's layers.

Code

\documentclass{book}
\usepackage{tikz}
\usetikzlibrary{shapes,arrows,positioning}
\pgfdeclarelayer{background}
\pgfsetlayers{background,main}

\tikzset{
    narrow/.style={draw, fill=blue!20, text width=2cm, text centered, minimum height=1cm},
    wide/.style={draw, fill=orange!20, text width=7.5cm, text centered, minimum height=1.75cm, rounded corners},
    tall/.style={draw, fill=green!20, text width=1.75cm, text centered, minimum height=7cm, rounded corners},
    squar/.style={draw, fill=yellow!10, text width=4.75cm, text centered, minimum height=3.75cm, rounded corners}
}

\def\blockdist{5}
\def\edgedist{5}
\begin{document}
\begin{tikzpicture}
  \node (lib)     [tall]   {Library};
  \node at (3,-1) (tman)    [narrow] {tmon};
  \node (ksman)   [narrow] [right=.75cm of tman]   {ksmon};
  \node (stsp)    [narrow] [right=.75cm of ksman]  {stosp};
  \node (deamon)  [wide]   [below=.75cm of ksman]  {base};
  \node (imgan)   [narrow] [above=.75cm of tman]   {img-analysis};
  \node (thrman)  [narrow] [above=.75cm of imgan]  {thermal-analysis};
  \node (scrpts)  [squar]  [right=.75cm of thrman] {Scripts};
  \begin{pgfonlayer}{background}
    \fill[red!25] ([shift={(-.35,.35)}]tman.north west) rectangle ([shift={(.35,-.35)}]stsp.south east);
    \fill[red!50] ([shift={(-.25,.25)}]ksman.north west) rectangle ([shift={(.25,-.25)}]stsp.south east);
  \end{pgfonlayer}
  \node[fill=blue!30,above=.4cm of scrpts.center] (scriptsnode) {Hello, I am a node!};
\end{tikzpicture}
\end{document}

Output

---

Maybe you're aiming for a more automatic way; you can use the fit library (\usetikzlibrary{fit}) for that and instead of the rectangles you now can do:

  \begin{pgfonlayer}{background}
     \node [fill=red!50, inner sep=.35cm, fit=(tman)(stsp)] {};
     \node [fill=red!25, inner sep=.25cm, fit=(ksman)(stsp)] {};
%    \fill[red!25] ([shift={(-.35,.35)}]tman.north west) rectangle ([shift={(.35,-.35)}]stsp.south east);
%    \fill[red!50] ([shift={(-.25,.25)}]ksman.north west) rectangle ([shift={(.25,-.25)}]stsp.south east);
  \end{pgfonlayer}