LemonTree – Support for SysMLv2

LemonTree is already established globally as a commercial diff and merge tool, though primarily for Enterprise Architect UML / SysMLv1 models. For SysMLv2, LemonTree supports the textual notation (.sysml) and the official exchange format (.json) based on the new standard. Consequently, it supports all modeling tools that also implement the new SysMLv2 standard and therefore offer these formats.

Dr. Konrad Wieland, Managing Director of LieberLieber, comments: “We welcome the introduction of SysMLv2, which enables us to exchange data with many other tools on the modeling market. However, we would like to emphasize that while SysMLv2 models can be processed with purely textual diff and merge tools, only LemonTree ensures that the result is consistent and valid.”

LemonTree reads the entire model content and interprets the complete dependency graph. This allows the effects of changes to be displayed in a comprehensible manner. This is particularly necessary when a complex scenario is defined in a SysMLv2 model and a change to a definition (part defs) affects many of the derived instances (parts). Philipp Kalenda, Head of Consulting at LieberLieber: “Even if the model is edited in parallel via a view and the text editor, the merge in LemonTree always takes place via the underlying model and not via a textual merge.”

The following features are planned for the first preview version of LemonTree 5.0 at the end of June 2026:

• Diff and merge of textual notation (.sysml files)
• Diff and merge of the SysMLv2 exchange format (.json)
• Migration from .sysml to .json and vice versa
• In LemonTree, it will be possible to use impacted elements, the model tree, and textual notation for diff analysis. A graphical notation display is already in development. 

The Object Management Group (OMG) recently published the final specifications for KerML v1.0, SysML v2.0 and the Systems Modelling API v1.0, thereby heralding a new era in MBSE.

With the SysMLv2 specifications, the official reference documents for the next generation of model-based systems engineering (MBSE) are now available. LieberLieber has also been engaged with this topic for some time, for example at the MBSE Summit 2025 in Traunkirchen, at several INCOSE presentations, and during an in-house training session with Vince Molnar in Vienna. Last but not least, the new standards are also being incorporated into the product development for LemonTree 5.0. The new release will be presented in a webinar on 24 June 2026.

Vienna 20.5.2026  – The new OMG standards form the basis for modernised, consistent and interoperable modelling – from a precise foundation (KerML), through the Systems Modeling Language (SysMLv2), to the technical interface (Systems Modeling API). This move was prompted by the limitations of UML, which is a modelling language for (object-oriented) software systems. Furthermore, SysMLv1 contained inconsistencies in semantics and offered few opportunities for reusing models or for automation. An API has also been specified that allows data from a SysMLv2 model to be queried in a structured manner. .json was adopted as the new exchange format, which finally leads to standardisation and significantly facilitates the exchange of data between previously incompatible modelling systems.

LemonTree – Support for SysMLv2

LemonTree is already established globally as a commercial diff and merge tool, although primarily for Enterprise Architect UML / SysMLv1 models. For SysMLv2, LemonTree supports the textual notation (.sysml) and the official exchange format (.json) based on the new standard. Consequently, all modelling tools that also implement the new SysMLv2 standard and therefore offer these formats are supported.

Dr Konrad Wieland, Managing Director of LieberLieber, comments: “We welcome the introduction of SysMLv2, which enables us to exchange data with many other tools on the modelling market. However, we would like to emphasise that whilst SysMLv2 models can be processed using purely textual diff and merge tools, only LemonTree ensures that the result is consistent and valid. We will therefore be presenting the new capabilities of LemonTree 5.0 in a webinar on 24 June 2026.”

LemonTree 5.0 is coming soon

LemonTree imports the entire model content and interprets the complete dependency graph. This allows the effects of changes to be displayed in a clear and understandable way. This is particularly necessary when a complex scenario is defined in a SysMLv2 model and a change to a definition (part defs) affects many of the instances derived from it (parts). Philipp Kalenda, Head of Consulting at LieberLieber: “Even if the model is edited in parallel via a view and the text editor, the merging in LemonTree always takes place via the underlying model and not via a textual merge.”

The following features are planned for the first preview version of LemonTree 5.0 at the end of June 2026:

• Diff and merge of textual notation (.sysml files)
• Diff and merge of the SysMLv2 exchange format (.json)
• Migration from .sysml to .json and vice versa

In LemonTree, it will be possible to use Impacted Elements, the model tree and the textual notation for diff analysis. A graphical representation of the notation is already in the works.

The Versicherungskammer Bayern (VKB) Group comprises eleven insurance companies and regional brands and employs around 7,500 people. For several years now, a team of around ten people has been using Enterprise Architect as a tool for defining insurance products. With the introduction of LemonTree and the development of a suitable Git workflow, precise version control has now also been achieved.

Vienna / Munich – With around 7,500 employees, Versicherungskammer Bayern (VKB) is Germany’s largest public provider of personal and property insurance. The company pays out over €30 million daily in claims and benefits. To ensure its product range remains up to date, a team of around ten people uses Enterprise Architect, LemonTree and SmartGit to develop new insurance products via Enterprise Architecture Management (EAM).

René Schwaiger has been with VKB for about a year and works as a Business Architect in the modelling team: “As insurance products are quite complex, we end up with very large volumes of data in the models. Although there is a separate model for each product, ultimately everything is stored in a central file, as the whole system is based on a uniform structural model. Until now, this meant that any cross-cutting change involved a great deal of effort, and not everyone could work on the modelling in parallel. That’s why the desire for a change arose, and we discovered LemonTree and SmartGit through LieberLieber.”

Dr Konrad Wieland, Managing Director of LieberLieber: “LemonTree has proven its value very successfully in model-based systems engineering (MBSE) in recent years. At the same time, however, the importance of EAM for companies has also grown, and we see an interesting area of application for our expertise here. We are therefore delighted to have gained a client in VKB who has recognised the benefits of our EAM offering and is introducing new work processes together with us. Thanks to VKB’s confidence in our expertise, we are working together to overcome the challenges we face and are opening up a new area of application for LemonTree.”

Clearly defined Git workflow

 Using Git is often a challenge for newcomers. It was therefore essential to make the Git workflow as simple as possible. Based on the type of changes required at VKB, a clearly defined workflow was established in joint workshops. Philipp Kalenda, Head of Consulting at LieberLieber, comments: “Over the last few years, we have been working intensively on how we can expand LemonTree to ensure success in the EAM sector as well. A major stumbling block here is working with Git, which needs to be simplified. VKB is a pioneer in this field, and together we have been able to develop a suitable Git workflow. When venturing into such uncharted territory, it takes a great deal of openness and a willingness to learn on all sides to solve the problems that arise together, step by step.”

The diagram shows a simplified version and branching history of a product, in which the underlying model is developed in parallel across several branches in Enterprise Architect. Starting from the main branch (V1.0), two product branches (Product001 and Product002) are created, in which changes are made to the model independently. The resulting model changes are then merged using LemonTree (including conflict resolution) and integrated into the main branch (V2.0).

As the INCOSE International Workshop 2026 (Torrance, California) was themed ‘Towards Continuous Integration’, Phillip Kalenda, Head of Consulting at LieberLieber, presented how clients successfully implement CI/CD using system models. The presentation explained how model-based systems engineering must adopt DevOps practices in the style of software development so that system models can be versioned, branched, validated and integrated via CI/CD pipelines in exactly the same way as source code.

The presentation highlighted LieberLieber’s core competence, in which the company has already gained more than a decade of experience:

• Model versioning
• Diff/merge technology
• Introduction of Git-based workflows in the field of systems engineering for cyber-physical systems

The presentation also highlighted important use cases for CI/CD with models that LieberLieber’s customers use:

• Model-based reviews
• Automated code generation
• Model warehouse
• Model publishing
• Tool integration

In the outlook for SysMLv2, it was made clear that all the principles presented are also valid for v2 models and will be supported by the LieberLieber toolchain in the future.

Extensive experience with CI/CD

This year, the LieberLieber team was particularly struck by the presentations on the topic of CI/CD (Continuous Integration / Continuous Delivery). “For LieberLieber, CI/CD is not a new topic. We now have several years’ experience in this area and support customers with commercial products such as LemonTree,” explains Kalenda.

Thanks to textual notation and the SysMLv2 REST API, the CI/CD approach is more easily accessible with build server automations. Tools will therefore be geared in future towards adopting CI/CD principles from software development. This focus aligns with the fundamental LieberLieber philosophy: “Model-based team collaboration using strategies from software engineering”. That is why Philipp Kalenda gave the CI/CD presentation “Making System Models First-Class Citizens in CI/CD – Rethinking Model Management 10 Years for CI/CD” at the INCOSE International Workshop “Towards Continuous Integration” in January 2026.

LieberLieber partners from Japan, Italy, Scotland, Germany and Austria recently met for an exclusive three-day training course in Vienna. The course presented the latest developments relating to LemonTree and provided practical insights into day-to-day work with MBSE (model-based software and systems engineering). The great success of the event underscores the desire to continuously expand the partner landscape in order to better inform the market about LieberLieber’s offerings.

Vienna – The three-day event with LieberLieber partners consisted of a mixture of technical input, lively discussions and relaxed leisure activities. Danja Stiegler, who recently became partner manager at LieberLieber, said: “It was very interesting for me to get to know the various people from our partner companies better. We wanted not only to provide in-depth technical insights, but above all to take advantage of the valuable opportunities for exchange and strengthening our partnerships. We would like to thank all participants for their friendly commitment and we are already looking forward to the next steps together.”

Relaxed dinner (front right: Daniel Siegl)

Exclusive insights into the LemonTree roadmap

The event concluded with an insight into the LemonTree Roadmap 2026, which was presented for the first time. The highlights prepared by the LieberLieber development team are:

• SysML V2 in LemonTree – the next evolutionary step for modern, collaborative model management
• LemonTree Dashboard – enables intuitive versioning of models without Git knowledge
• LemonTree4Codebeamer – takes versioning and comparison of Codebeamer baselines to a new level

“The positive feedback confirms that we were able to show our sales partners how important they are for the continued positive development of our company. Our task is, of course, to continuously develop our product range and to support our partners with advice and assistance. Part of this partner strategy includes training courses such as this one at our headquarters in Vienna, which are very popular for professional and personal exchange. I am looking forward to many interesting customer projects in which we can work with our partners to demonstrate and implement the great opportunities offered by MBSE. At the same time, we are working to attract new partners in order to make even better use of our market opportunities,” Wieland sums up.

At SafeSec Day 2025, organised jointly by TÜV Akademie Austria and msg Plaut Austria, Markus Benedikt from LieberLieber held a workshop explaining the integration of safety and security standards in model versioning with LemonTree, using practical examples.

In his workshop, Markus Benedikt emphasised the major advantages of model-based systems engineering (MBSE), which range from reducing the complexity of requirements to the verifiable integration of safety and security standards. “MBSE makes it very easy to reduce physical and digital risks in products and systems. To make the principles to be observed clear and easy to understand, I chose the practical example of “developing a smart water boiler,” explains Benedikt. Let’s assume that a company is developing a smart water boiler with IoT functions that can be controlled via an app and displays the water level, temperature and energy consumption. During development, all relevant safety and security standards must of course be taken into account:

• Safety: Prevention of physical hazards such as overheating, electric shock or improper use
• Security: Protection of user data and prevention of unauthorised access to the kettle

This integrated setup demonstrates how Enterprise Architect (EA), combined with LemonTree and version control systems like Git, enables a consistent and traceable model management workflow. By automating synchronization through LemonTree.Connect and LemonTree.Automation, and centralizing collaboration with Pro Cloud Server and WebEA, teams can ensure seamless versioning, efficient reviews, and clear traceability across distributed environments. This approach supports model integrity, accelerates feedback cycles, and enhances overall project transparency and collaboration.

The control of a microgrid is being optimised in the EU project MATISSE through model-based development of digital twins. LieberLieber is part of the European research project MATISSE, which aims to develop ‘model-based digital twins for the early verification and validation of industrial systems’. In a specific use case, work is now underway to leverage digital twins to continuously and automatically improve the operation of an existing microgrid at Siemens Austria.

Vienna  – The Siemens use case in the MATISSE research project relates to the control of an intelligent microgrid. Such microgrids usually consist of at least one energy resource (e.g. a photovoltaic system) and, if necessary, an electricity storage facility, charging points for electric cars, load management and an interface to the building management system. ‘ Microgrids are typically controlled by static rules. By modelling a digital twin, we want to switch the control system to one that automatically adapts to current conditions and thus ensures optimal operation,’ explains project manager Danilo Valerio from the research department at Siemens Austria. A microgrid with various e-mobility charging stations on the Siemens campus in Vienna is being used as a test environment. The ‘Configuration Technologies’ research group at Siemens Austria is contributing its hybrid and neurosymbolic AI research to the project.

Applied research for European industry

MATISSE aims to use concrete case studies to enable European research and industry to offer services based on digital twins, including verification, prediction and monitoring, thereby improving the overall development and integration of digital twins. These efforts rely heavily on the use of models and model-based techniques, including both general languages such as UML/SysML and domain-specific languages (such as VVML) and model transformations.

“The goal in our use case is to develop a solution that works on a plug-and-play basis without having to define all the operational details of the microgrid in advance. To achieve such an ambitious goal, the solution must be able to continuously complete the knowledge base. We plan to do this using neurosymbolic AI approaches and inductive logic programming,” Valerio continues.

The research group at Siemens Austria expects very specific results from the MATISSE project:

• Automated pipeline for creating digital twins for complex microgrid systems using MBSE
• Review and real-time adjustment of the created digital twin in terms of model fidelity and simulation accuracy through continuous verification and validation
• Optimisation of microgrid operation through learned and dynamically adapted rules, taking real-time factors into account (e.g. weather forecasts, seasonality)
• An integrated toolkit for the digital twin-based verification and validation of optimised microgrid operation