Domain-Driven Design Europe

Henning Schwentner - DDD for Mergers and Acquisitions - DDD Europe 2025

Henning Schwentner opened his talk with a tongue‑in‑cheek love story, then pivoted to the real challenge: integrating two legacy leasing platforms after a merger. He framed the problem as a choice between keeping both monolithic systems in parallel or consolidating into a single solution, warning that either extreme can erode expected synergies. He introduced collaborative modeling—event storming, domain storytelling, and other lightweight workshops—as the means to surface hidden process variations between the acquiring firm (Alhorn) and the target (Cosmo). By applying three scope dimensions—granularity, point‑in‑time, and domain purity—teams can decide how detailed a model should be, whether to map current or future processes, and whether to focus on business logic or its digital implementation. Schwentner illustrated these concepts with a step‑by‑step comparison of the leasing workflow, moving from a high‑level "cloud" view down to the "kite" level where divergences appear, such as contract signing steps. He argued that outright system replacement is rarely viable; instead, modularizing and modernizing each monolith, then recombining the best bounded contexts, yields a more sustainable architecture. This approach, he called Domain‑Driven Transformation, tackles strategic (big‑ball‑of‑mud), tactical (poor domain expression), and organizational (team structure) ailments. The takeaway for executives and architects is clear: use collaborative, scoped modeling to diagnose integration gaps, then apply domain‑driven modularization rather than a blunt data migration. This reduces risk, preserves valuable legacy functionality, and accelerates value capture from M&A activity.