Hamburg Leverages oneM2M Standards to Unite Legacy and Greenfield IoT for a Greener City

According to Ingo Freise, software architect at Deutsche Telekom, designing a distributed IoT system—whether for a factory or a smart city—requires careful attention to several key design principles.

A primary challenge is integrating legacy subsystems—like a final‑assembly cell—with new greenfield solutions such as image‑processing systems for quality control. Equally critical is harmonising diverse connectivity and data‑management technologies, often sourced from multiple vendors.

Deutsche Telekom addressed these challenges during the MySMARTLife project, a consortium partnership with Nantes, Hamburg, and Helsinki, where our focus was on implementing solutions for Hamburg.

Hamburg’s platform is built on an Open Geospatial Consortium (OGC) standard, serving as a common foundation for many cities. It underpins geo‑location services, surface‑planning tools, and daily municipal operations.

An Open‑Standards, Interoperable Framework

Hamburg’s transparency law mandates the publication of all publicly sourced data, from static datasets like school opening times to real‑time streams—for example, the operational status of electric‑vehicle charging stations.

We tackled two core challenges. First, we modernised data sourcing and publishing beyond legacy geo‑spatial systems. Second, we streamlined data access for users via an API. Although Hamburg already had an API, our assessment revealed the need for an enhanced, more capable version.

The upgraded API introduces granular access controls, allowing administrators to assign policies to endpoint devices and data sources. It also empowers data providers to manage security at a fine‑grained level for diverse consumer types, exemplifying how a basic API can evolve to support operational excellence and digital transformation.

Foundations for digital transformation

Committed to applied innovation, our team chose not to create a new platform from scratch. After evaluating FiWARE and oneM2M specifications, we selected oneM2M for its alignment with our Java expertise and Scrum‑based development process.

oneM2M is an open, globally recognised middleware standard that bridges IoT applications and the underlying device layer. It offers a standardized suite of tools—connectivity, subscription, security, and device management—that facilitate interoperable IoT ecosystems.

Its toolset covers connectivity, subscription, security, and device management, leveraging the LWM2M standard to avoid reinventing the wheel.

Partnering with the Fraunhofer IOSB, which built a server to harvest city data from parking lots and traffic lights, our team developed a oneM2M‑based data‑management platform that aggregates additional sources and publishes them to third‑party users. We integrated the two systems through an interworking proxy entity (IPE), a standardized component of the oneM2M toolkit.

The resulting architecture consolidates diverse city data streams and merges them with Hamburg’s native geospatial platform.

It provides an elegant integration of legacy brownfield systems with incremental greenfield sensor deployments, delivering a unified data access point for users across the city.

As manufacturers, municipalities, and service partners pursue Industry 4.0, smart‑city, and digital‑transformation agendas, architects must design interoperable, extensible systems grounded in open standards like oneM2M.

A key design principle for service providers, integrators, and IT teams is ensuring seamless interoperability between new and legacy systems, transcending departmental and operational silos.

The author is Ingo Freise, software architect, Deutsche Telekom.