4.33 Elementary Method "PIM - Process Interaction Modeling" (PIM)

  4.33 Elementarmethode "Prozeßinteraktionsmodellierung" (PZIM)

Contents		1 Identification/Definition of the Method 2 Brief Characteristic of the Method 3 Limits of the Methods Application 4 Specification of the Methods Allocation 5 Interfaces 6 Further Literature 7 Functional Tool Requirements

1 Identification/Definition of the Method

2 Brief Characteristic of the Method

The method "Process Interaction Modeling"(PIM) is a semi-formal method applied for the design of the signal exchange between several communicating realtime processes. The basic method specifies which signals or data are exchanged in what time sequence between which designed processes. PIM has the character of a static rule; it only handles the sequence of the signals and thus indirectly its causal relationship.

Means of Representation

PIM is represented by so-called "Sequence Charts" (SQ). The following notations can be considered as examples:

• In a SQ, processes are represented by special symbols (one vertical line with a process name at the upper end).
• Arrows with signal names point from any sender process to any other receiver process (arrowhead). Each process can send to several other processes or respectively receive from several other processes. In one SQ, the number of processes and signal arrows is not limited.
• The time runs downwards, along the line ensemble.
• Signals or data represented by one of the upper arrows have to be chronologically exchanged prior to signals represented by lower-laying arrows.

Operational Sequence

By applying the basic method, the dynamical interconnections in the process design are recorded and represented. Preparatory steps to generate the SQ (collection of signals and processes) are advisable, though not required. SQ can even be applied to find processes together with its communication requirements in a step-by-step manner, and to integrate them into a suitable causal relationship. In case the processes have already been identified and summarized in the process overview this is utilized by the method as an initial basis.

When generating an SQ, the following steps are typically performed:

• If not otherwise specified, all individual processes of the unit to be designed (in this case an SW Unit) are identified and named.
• For each of the individual sender processes, all signals or even data are identified and named, including the receiver process.
• After these preparatory steps, the framework of an SQ-the process lines-are generated. The signal arrows are entered between sender and receiver, in correspondence to its relative chronological order.

3 Limits of the Methods Application

4 Specification of the Methods Allocation

5 Interfaces

6 Further Literature

7 Functional Tool Requirements

GDPA Online Last Updated 01.Jan.2002 Updated by Webmaster Last Revised 01.Jan.2002 Revised by Webmaster