In today’s cities, seamless collaboration between different systems and stakeholders is essential for creating more connected, efficient, and inclusive communities. However, interoperability remains a major challenge. Minimal Interoperability Mechanisms (MIMs), facilitated by OASC, are a community-driven concept that provides simple yet effective guidelines for sharing data and integrating urban services.
To explore the real-world impact of MIMS, we spoke with Prof. Dessislava Petrova-Antonova, Research Leader of the Data Management Research Unit at the GATE Institute in Bulgaria. She is at the forefront of Sofia’s Urban Digital Twin initiative, a project leveraging advanced 3D City Information Models to analyse, simulate and visualise urban environments.
“We apply MIMs at every stage of the development of Sofia’s Urban Digital Twin—starting from data collection and management, moving to analytics and simulations, and finally reaching data visualisation.”
Discovering MIMs and Their Role in Sofia’s Digital Twin
Petrova-Antonova first met MIMs through OASC events and has since followed their development via official guidelines, the Living-in.EU movement, and LinkedIn discussions.
“After I became familiar with MIMs, I started actively looking for more information, speaking with colleagues, and following updates online,” she explains.
Key MIMs in use for Sofia’s Urban Digital Twin:
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MIM1 (Context Information Management): ““We need to integrate data from various sources—real-time sensor data, satellite and drone imagery, and dynamic data, produced by urban processes. We utilise data by developing RESTful Application Programming Interfaces (APIs) for sharing data in a structured manner based on different standards and widely adopted data models.”
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MIM2 (Common Data Models):
“The 3D city model of Sofia relies on the CityGML standard. We are also contributing to application domain extensions of the standard for vegetation and air quality, mapping them to FIWARE Smart Data Models.”
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MIM5 (Transparency): “We apply explainable Artificial Intelligence (AI) to understand how our models work—their accuracy, fairness, and bias. This is crucial for stakeholders to trust AI-driven decisions.”
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MIM6 (Security): “We follow GDPR regulations and sign Non-Disclosure Agreements (NDA) when dealing with third-party data. We also participate in the European Mobility Data Space deployment (deployEMDS) project, contributing to the local use cases of Sofia.”
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MIM7 (Fair AI & Geospatial Data): “We rely on GeoJSON, GML, and CityGML for geospatial data. We aim to improve interoperability through better data enrichment. For example, geocoding Cyrillic addresses in Sofia and enriching them with data from other data sources, including street and pedestrian networks, building and points of interest (POIs)”
The Benefits and Challenges of MIMs Adoption
For Petrova-Antonova, MIMs’ simplicity is its greatest strength.
“When interoperability mechanisms are simple, they are easier to follow and adopt. This allows us to scale systems efficiently, as they rely on common standards, data models, and technical building blocks.”
However, she acknowledges that adoption remains a challenge due to different communities relying on different standards.
“There is a gap between the FIWARE community, which uses Smart Data Models, and the geospatial community, which relies on OGC standards. That’s why we are working on mapping these standards to facilitate data interoperability.”
Additionally, while MIMs are designed to be minimal, some complex use cases require extensions.
“Minimal mechanisms can sometimes limit certain use cases. We need to find ways to extend MIMs for specific needs while maintaining their simplicity.”
The Future of MIMs in Sofia and Beyond
Sofia Municipality is actively incorporating MIMS into its urban planning strategies.
“Based on our experience in the development of the Urban Digital Twin, we support Sofia Municipality in specifying a data platform for its further development and scaling. Our recommendations are aligned with MIMs and even key MIMs principles are translated into Bulgarian to facilitate adoption.”
Dessislava believes that cities must explore open-source solutions instead of relying exclusively on proprietary software.
“For example, municipalities could use QGIS for geospatial analysis, CityGML for city data modelling and Cesium ion for 3D visualisations, open-source alternatives that can deliver the same results with lower costs.”
Beyond Sofia, Petrova-Antonova highlights the importance of international collaboration.
“We work with universities across Europe, such as the University of Twente (NL), to develop different urban digital twin use vases. Common standards like CityGML help us collaborate effectively, even when dealing with complex local challenges.”
Next Steps: Strengthening MIMs Adoption
Looking ahead, Dessislava Petrova-Antonova advocates for:
- More real-world case studies to showcase MIMs in practice;
- Stronger community collaboration through platforms like GitBook, where stakeholders can propose improvements;
- Training initiatives to help cities and researchers better understand MIMs.
“I would like to contribute as much as possible to MIMs adoption and the implementation of Local Digital Twins.”
As Sofia refines its Urban Digital Twin, its experience serves as a model for other cities looking to adopt MIMs-driven interoperability.
For more details on MIMs and smart city interoperability, visit: