A system can be described by agents that communicate with each other. The Paose1 approach combines this perspective with Petri nets. Mulan is a toolset that implements the Paose approach [1], extending the Petri net tool Renew2 with agent functionalities. There are a number of techniques that allow modeling use cases and interactions, some of them provided in the context of Paose. The goal of this paper is to further extend the capabilities of existing Paose techniques. For this, modeling functionalities are moved from Mulan to Renew, existing diagram types are interconnected, and the concept of refinement is presented. In the following, we describe the foundations for our work (sec. 2) and set the objectives of this paper (sec. 3). We then describe the realization (sec. 4), examine related work (sec. 5) and discuss our findings (sec. 6). Finally, we provide a summary and present possibilities for future work (sec. 7).
Paose is an approach that is described in detail by Cabac [
Cdds allow to create an overview of a system. They are based on UML Use Case Diagrams, consisting
of actors and use cases. While the syntax is maintained, both the semantics and the perspective are
adapted. Instead of users, actors represent agent roles as part of the modeled system. Use cases represent
interactions within the modeled system, not with it [
Aips provide an easily readable technique for modeling interactions between multiple roles that are
taken by agents [
Renew is a tool originally designed to draw and simulate diferent Petri net formalisms [
In the followup of redesigning Renew (see [
Based on this, the functionalities of implementing Cdds in Renew, associating Aips with use cases and introducing refinement and coarsening for Cdds were proposed. The current state of our work is presented in section 4.
As a first step, we introduced the Cdd functionality as a new plugin in Renew. For this, we copied the original Mulan plugin and reduced it to its core features. Following the transfer, additional small enhancements were implemented to improve the Cdd functionality, including syntax checking and improvements regarding usability. Adding Cdds in Renew allows to further extend its functionality and use Cdds in a more general modeling context.
While Cdds describe what interactions are taking place[
Abstraction and concretion are common strategies for dealing with complexity, describing the same system at diferent levels of detail. In the context of Petri nets, these terms are also defined as coarsening and refinement. In our third step, we discussed how to apply these concepts to Cdds and their elements. As a first idea on how to describe the elements in more detail, we allow marking an actor or a use case as to be refined. The marked element can then be refined in a separate diagram. For refining one single actor or use case, any number of actors and/or use cases can be used. The same idea can be applied in reverse: a number of elements marked for coarsening can be represented by one abstract actor or use case.
HERAKLIT is a modeling technique based on Petri nets [
In a more general context, the idea of abstraction and concretion was applied to use case diagrams in
[
In [
With the new features, the modeling capabilities of Renew are extended. While associating Aips with use cases allows combining multiple types of diagrams, refinement and coarsening allows combining multiple levels of abstraction within one model. Although refinement and coarsening have not yet been implemented, the described concept provides a clear path for implementation. Both features can also be combined. Once implemented, they allow for a model that provides navigation through diferent levels of abstraction and diagram types.
We moved the Cdds from Mulan to Renew and enhanced them with the option to interactively attach Aips. Additionally, we introduced the concept of refining use cases as well as actors by allowing each element of a Cdd to be refined with an additional Cdd detailing it. Since each element can be refined by both additional actors and use cases, internal orchestrations can be modeled. This permits visualization of larger systems at various levels of abstraction as required.
So far, we are refining single use cases or actors, but it should be possible to refine multiple actors
and use cases together. The guiding idea is to follow the associative composition of Fettke and Reisig
with their HERAKLIT approach [
While this work mostly describes the refinement within use case diagrams and expresses coarsening as a simple reverse operation, starting with a complex diagram and wanting to abstract or coarsen parts of it is a diferent matter. It remains to be seen on how this can be implemented and how the context of Petri nets can be used.
Another point of interest is whether additional functionality can be transferred from Mulan to Renew, taking domain driven design (DDD) into consideration regarding the modularization of functionality.
As Renew already contains general modeling techniques like BPMN, and now allows to create use case diagrams, further extending Renew with additional general diagram types could be considered.
During the preparation of this work, the authors used DeepL and LanguageTool in order to: Grammar and spelling check, Paraphrase and reword. After using these tool(s)/service(s), the authors reviewed and edited the content as needed and take full responsibility for the publication’s content.