The RE-Tools for Requirements Engineering

by Sam Supakkul

Support for the NFR Framework | Support for the i*/Tropos Framework | Support for KAOS | Support for Problem Frames | Support for the WRSPM Reference Model

View this page in Romanian (courtesy of Alexandra Seremina and azoft).

The RE-Tools supports the following notations:

The NFR framework for non-functional requirements (NFRs) modeling
The i* Framework/Tropos for agent-oriented modeling
KAOS for formal goals modeling
Problem Frames for business and system requirements and specifications modeling
UML for object-oriented modeling

The RE-Tools is a model-based modeling tool. All supported notations can be used together in an integrated manner, which means functional and non-functional requirements, agents, goals, softgoals, formal goals, and objects can be related as needed. Examples of the NFR Framework being used with KAOS and Use Case Modeling are illustrated below. More examples of integrated modeling using multiple notations are available here.

The tool is implemented as a UML Profile that extends an open source UML modeling tool called StarUML. User models can be programmatically reasoned about and manipulated by external programs via APIs. For example, the demo video below shows the reasoning on an NFR graph to evaluate the goal satisficing label of low-level goals to derive the satisficing label of high-level goals.

Currently, the RE-Tools is reasonably useful as a modeling tool, but needs more reasoning and integrity enforcement support for the respective notations. It is therefore released as an open source tool under GPL to encourage more research and extensions so that it can serve as a useful research tool or perhaps eventually become a useful integrated tool for practitioners.

The RE-Tools can be downloaded from here. Any questions and comments are welcome. Please email them to "ssupakkul (at) ieee.org".

Support for the NFR Framework

The RE-Tools the NFR Framework as defined in this book and this paper, with an extension to support both closed and open world assumptions for goal satisficing label evaluation. See more detailed discussions on the label evaluation here.

The tool also supports Problem Interdependency Graph for modeling obstacles to goal achievement. More discussion about the problem modeling is available here.

The latest version (1.2) has implemented automated goal achievement evaluation based on the label evaluation procedure defined by the NFR Framework. Below is a demo of the feature. A larger video is available here.

Figure 1. A Softgoal Interdependency Graph

Figure 2: An Integrated Softgoal Interdependency Graph and Problem Interdependency Graph

Figure 3: An Integrated Use Case and NFRs Diagram

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Support for the i*/Tropos Framework

The tool supports the modeling of Strategic Dependency (SD) and Strategic Rationale (SR) diagrams of the i* Framework. Since the NFR Framework is adopted by the i* Framework for dealing with NFRs, the icons related to NFRs are only provided on the tool panel for the NFR Framework. while the features that are unique to the i* Framework are provided on the i* Framework panel.

Figure 3. A Strategic Dependency Diagram

Figure 4. A Strategic Rationale Diagram

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Support for KAOS

The RE-Tools supports many concepts defined in the seminal paper on KAOS with influences from the KAOS UML Profile. Further extensions were made to support the following:

monitors and controls as described here
different icons for "requirement" and "expectation" goals
different icons for people, hardware, target software (software under development), and external software, as suggested by Lawrence Chung.

Figure 5. A KAOS Goal Model

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Support for Problem Frames

The Problem Frames method was originally developed for system level requirements and specifications modeling, but has been adopted for business modeling. The RE-Tools provides two sets of Problem Frames notations: one for the classic notation as defined in this book for system level requirements and specifications modeling, and another (icons with a back slash on the top right corner) for organizational requirements and specification as described in this paper.

Figure 6. A Business Problem Diagram

Figure 7. A System Problem Diagram

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Support for the WRSPM Reference Model

The RE-Tools is built on top of the StarUML tool. To create a new model, the user must selects an Approach, a notion referring to a modeling framework, e.g. the use case driven 4+1 View approach. The notations supported by the RE-Tools are available to the users regardless of which StarUML Approach is selected by the user. However, the RE-Tools also provides a special Approach called the "WRSPM" Approach to support the Reference Model for software requirements and specifications. If the WRSPM Approach is selected by the user, the RE-Tools will create a blank project with a pre-created model structure consisting of the World, Requirements/Specifications, Program, and Machine modules as defined by the Reference Model, with an initial set of suggested diagrams for each artifact type, where each diagram can be removed or additional diagrams can be added as needed.

Figure 8. Model Structure Supporting the WRSPM Reference Model

Using any StarUML Approach, (e.g. "4+1" or "WRSPM"), the supported diagrams can be created from the menu bar or from the Model Explorer as shown in Fig. 9 below. Notice that the RE-Tools provides augmented UML diagrams (e.g. Class-NFR, UseCase-NFR, Component-NFR) so that NFRs may be modeled in those diagrams as shown in Fig. 2. However, currently NFRs cannot be modeled in statechart, sequence diagrams, and activity diagrams due to the restriction imposed by StarUML that UML class (the physical representation of NFR softgoals) is not allowed in those behavioral diagrams.

Figure 9. Creating a New Diagram

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