Functional safety standards such as ISO 26262 also require configuration and change management in models. LemonTree is used for this purpose in the software development of a leading German automotive supplier. The tool’s user-friendly features make the work of the developers much easier while reducing the rate of error.

Vienna – Especially in the automotive industry, verifiable compliance with functional safety standards such as ISO 26262 is essential. This means that manufacturers and suppliers are also obliged to perform configuration and change management in their models. “For us, various safety standards such as Automotive SPICE and compliance with the ‘Automotive Safety Integrity Level (ASIL)’ are decisive for software development. Since the Enterprise Architect modeling platform has been used successfully in the Software Architecture department for some time, we were convinced of the usefulness of model-based software development. However, it is only through the contact with LieberLieber and the use of LemonTree that our daily work with modeling is now considerably easier and faster,” says the employee of a leading German automotive supplier who is involved in the creation of safety-critical software in the functional software department. While Enterprise Architect has been in use in the company for a long time in the area of systems architecture, the platform is now increasingly finding its way into software development with the expansion by LemonTree. For this it was necessary, however, that LemonTree supports the company’s own modelling language and also enables markups with defined safety levels.

All changes easily confirmed
In order to be able to prove compliance with all legal requirements even when changes are made to the software, reviews are particularly important for the working group at the automotive supplier. The work results of the software development are checked manually in order to ensure the required quality. “Every change in our model – also known as a change request – must be subjected to a review. LemonTree offers excellent opportunities for this, which greatly accelerate our work,” says the employee. Whereas previously only small changes could be reviewed between two model versions, LemonTree extends the possibilities to more complex models and supports the work with many useful features. Dr. Konrad Wieland is responsible for LemonTree at LieberLieber: “This is a typical use case for LemonTree because change management combined with the review of models is mandatory for all companies that create software in the field of functional safety. We are pleased that, thanks to great demand, we can continue to expand the benefits of LemonTree for this scenario”.

Only the essentials are visible
The development team at the automotive supplier also wants to be able to concentrate on the essentials in their daily work. For the process of reviewing all of the changed elements in the model, LieberLieber has installed special filters that guide the user through the process with suggestions. During the review, elements that have already been tested by several persons can also be specially marked in order to avoid unnecessary double testing. “Thanks to the adjustments made by LieberLieber, LemonTree now supports us very individually in the review processes defined by us. Practical simplifications such as the clear highlighting of changes in diagrams or the possibility of simply dragging windows larger for better visibility make the tool practically indispensable in the meantime,” emphasizes the employee. The new quality of work will now be presented and discussed at a cross-departmental review meeting to pave the way for broader application within the company.

Screenshot 1: A single diagram is detachable from the main user interface of LemonTree and can be moved to another display or viewed as a maximized window.

Screenshot 2: The “Impacted Elements” and “Impacted Diagrams” lists are filterable. Among other things, there are prefabricated filters for this, such as #Removed or #Reviewed. The list will then only show elements / diagrams that match the filter criterion. All unaffected elements / diagrams are “grayed out”.

Screenshot 3: The so-called “3rd diagram” shows a preview of the merged diagram.

Screenshot 4: The “New Session Dialog” has been changed. It is now possible to load saved LemonTree sessions and start the respective mode with the “Merge” or “Compare” buttons. (Compare starts LemonTree with 2 columns to perform a “Diff”, Merge starts LemonTree with the two Compare columns and a Merge Preview column).

LemonTree for change management and model review
Functional safety standards such as ISO26262 require configuration and change management for all development-related artifacts. Models are now an integral part of the development process, especially in the development of safety-relevant mechatronic systems, and must therefore be subject to appropriate change management. With LieberLieber LemonTree, these changes are prepared in a comprehensible way and can be queried at any time. Not only the current status of the model is important, but also the changes to the model or between individual versions of the model. Information about which user has changed something in the model and when is not only helpful when it comes to teamwork, but is also indispensable in the functional safety area. LemonTree also makes it possible to examine or “review” these changes. The sophisticated presentation of the changes and the filter options in LemonTree facilitate this work enormously. In addition, LemonTree offers sophisticated features to save a review configuration including the model versions to be reviewed and the current status of the review. This makes it possible to pause the review process at any time and then continue without any loss of information. Last but not least, review comments can be added to your own branches in a comprehensible way to support an optimized review process.

The advantages of LemonTree:

  • Reliable auditing according to ISO standards
  • Traceable changes
  • Merge review comments
  • Additional checkmarks for filtering already-reviewed changes
  • Filter options in the change list
  • Export of changes as CSV file
  • XML export for your own change visualizations
  • Change history available

Benefits to users
With LemonTree, modelers and reviewers have the assurance that all changes to the UML or SysML models are reliably merged and each change is precisely documented. The complete information about which user has changed exactly what and when is extremely important in the development of security-relevant artifacts or in other areas. The model changes are presented in a comprehensible way and can be subjected to a controlled review at any time. Supplementary review comments are maintained in a separate model version, which guarantees the user that the productive model will not be destroyed. If several reviewers maintain such comments, they can also be easily merged with LemonTree. Various export options (e.g. XML) serve to document changes over time.