someone is typing on a laptop an a cup of coffee is standing next to the laptop

Modernisation of the existing core system



After DAK-Gesundheit converted its core health insurance systems to a new standard solution, the old host-based system still contained a lot of historical insurance data that had to be kept searchable for over 30 years. The former core system was run on an IBM mainframe, was coded in COBOL and was cost-intensive to run and maintain. In addition, DAK hardly employed any host developers at that time, so that there was a very high risk for the long-term continued operation of the old application.

By using the adesso transformer, the complex business logic of the old core system was effectively transformed to Java. At the same time, an intuitive and modern user interface for searching and displaying archived insurance data was developed in the project.


With the new user interface of the archive product to be developed, the work processes of the clerks are now simplified and process cost savings are realised. With this modernisation of the mainframe-based legacy application, the company saves a double-digit million amount per year after switching off the IBM mainframe.

Advantages for the customer

With the successfully implemented modernisation scenario, DAK benefits from a largely automatic transformation of the business logic and from the minimisation of the migration effort. In addition, the new solution represents a future-proof target architecture, saves operating costs and significantly reduces maintenance and failure risks.

adesso services

  • Tool-supported analysis of the existing legacy system
  • (Partially) automated transformation of relevant COBOL programmes
  • Adaptation/transformation of the deletion concept for social data implemented on the host (JCL transformation)
  • Conception and implementation of the data migration Db2 for z/OS and IMS DB to Db2 LuW
  • Support for the requirements specification of the information processes to be implemented
  • User Experience Design
  • Development of a new and process-oriented frontend for case processing
  • Project planning and project management
  • Conception of the target architecture
  • Evaluation of the modernisation paths
  • Creation of the test concept and implementation
  • Knowledge transfer (including a training concept)
  • Documentation of the necessary adjustments to the system
  • Adaptations of the interfaces (conception, implementation, integration, commissioning, documentation as well as knowledge transfer)

Technologies and methods used (excerpt)

The following technologies and methods were used in the project:

Source systems:
  • IBM z/OS
  • CICS
  • BMS
  • Db2 for z/OS
  • JCL
Target architecture:
  • Java8
  • Java Spring MVC
  • Spring Framework
  • Java Rest-Services
  • HTML5/CSS3
  • Thymeleaf
  • Maven

The DAK-Gesundheit, based in Hamburg, is a German health insurance company operating nationwide. It is a public corporation with self-administration within the statutory health insurance.

Logo DAK

Do you have any questions?

We will happily transform a small, representative application sample as part of a free feasibility check and develop a unique transformation project for you on this basis.


Save this page. Remove this page.