-diagram - Databases


Charts are used to display input-output processes. Initially, the methodology SADT, which was mentioned earlier, was used, then switched to DFD schemes. Two main types of notations are used: Jordan-Demarco and Hein-Sarson. The differences between them are not large and therefore we use the Hein-Sarson notation. Symbols with names are used in the notation.

Barker Notation Model

Fig. 3.7. Barker Notation Model

Context diagram of the recruitment process

Fig. 3.8. Context diagram of the recruitment process

DFD is built on the basis of decomposition and the top-level model is called the contextual diagram. In any particular project, it is one. Such models describe the control object, and for the reflection of the control part (UC) of the system, a real-time extension is applied [25]: the listed symbols are drawn with dashed lines or dots. The main types of control streams are the T-stream (trigger), A-flow (the process is continuous until the stream is turned off), E/D-push-button (analog of the switch with two buttons is on and off).

The illustration is based on the recruitment process described in Example 2.2.

Detailed diagram of the recruitment process

Fig. 3.9. A detailed diagram of the recruitment process

Extended recruitment process diagram

Fig. 3.10. Extended recruitment process chart

The contextual Heine-Sarson diagram is shown in Fig. 3.8: it allows you to see the input and output streams and external entities (data sources and/or receivers) "Customer" and Manufacturer & quot ;. A detailed diagram of the process under consideration can be represented in the form shown in Fig. 3.9 with processes 1-5, where DB1 is data or a part of them stored in memory. In general, each of the processes 1-3, in turn, can be detailed. The expanded diagram is shown in Fig. EVIL.

A particular case of the decision-making algorithm, when the number of vacancies exceeds the number of vacancies, is shown in Fig. 3.11.

Fig. 3.8-3.11 allow us to note that the flows have explanations. Textual modeling tools are called data dictionary.


It is used to display the development process and the results of implementing solutions. The concept of state is introduced. Schema (transition scheme) for the Rules (Figure 3.11) can be as shown in Fig. 3.12. The process of changing the state can be reflected using a table (Table 3.2) or a matrix (Table 3.3).

After reviewing the details of the CASE-technology, let's return to the system aspect. " CASE-technologies can be classified according to several criteria.

1. On the scales - Software Engineering (SE) and Information Engineering (IE). The first scale is designed for software design and is well known (actually described in this paper), the second one is new, with a wider scope of application (for designing not only software).

2. In the order of building the model: a) procedure-oriented (modern approach); b) data-oriented (traditional approach).

3. By the type of target systems - for real-time systems (managing complex structures of large amounts of data with intensive I/O) and information systems (managing events with a small number of simple data with intensive calculations).

The system of recruitment rules for a scientific institution

Fig. 3.11. The system of rules for hiring a scientific institution:

G - vacancy; N - applicants and vacant posts; Л - the scientific degree; In - the accepted made an opening; C - the average grade of study; D - work experience, years

STD for the recruitment process

Fig. 3.12. STD for the recruitment process: a - the general scheme; b is an example

Table 3.2

Decision table

Current state



Next state

Initial state

Activated at the beginning of each session


Rule 1




Rule 2




Rule 3

Design Engineer



Rule 4

Operations Engineer



Rule 5



thematic pictures

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