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Subsections

6.3 The System Network Diagram Editor (TSND)

6.3.1 Nodes and Edges

In order to be able to edit a system network diagram as a graph, a system network connection in TSND is a compound connection consisting of three parts: one node and two edges. The node is one of State vector, Data stream or Controlled data stream. The two edges are a Connection start edge and a Connection end edge. These two types of edges do not have a name label but they can both have a cardinality constraint label. The cardinality constraints should conform to the same syntax as in section 4.1.2. Compound connections connect system network processes (abbreviated to SN processes). See figure 6.10 and 6.11 for the representations and the permitted connections (immediately enforced). For an example system network diagram, see figure 6.12.

**Figure 6.10:** *System network diagram nodes and edges.*
$\begin{figure} \begin{center} \begin{tabular} {\vert c p{1.45in}\vert c p{1.45in... ...nd{minipage} & Connection end \ \hline \end{tabular}\end{center}\end{figure}$

**Figure 6.11:** *Permitted system network diagram connections.*
$\begin{figure} \begin{center} \includegraphics {p/SNconnections.eps}\end{center}\end{figure}$

**Figure 6.12:** *Example system network diagram.*
$\begin{figure} \begin{center} \includegraphics {p/systemnetworkexample.eps}\end{center}\end{figure}$

6.3.2 Constraint Checking

In addition to the constraints mentioned in the previous section about TSND, TSND checks the immediately enforced and/or soft constraints that are summarized in figure 6.13.

**Figure 6.13:** *Immediately checked and soft constraints on SNDs.*
$\begin{figure} \begin{center} \includegraphics {p/SNconstraints.eps}\end{center}\end{figure}$

Next: 7 Table Editing Up: 6 Function View Editors Previous: 6.2 The Data and

Frank Dehne,Faculty of Mathematics and Computer Science, Vrije Universiteit Amsterdam
11/17/1997