Software Development for Eckert & Ziegler BEBIG GmbH

Challenges and Partners

Developing a medical device with a high proportion of software in a multi-regulated environment is a complex task. The security requirements are high and the architectural decisions to be made are far-reaching. As the number of available employees was limited, it was clear at an early stage that Eckert & Ziegler BEBIG would not be able to successfully complete a project without external support. One of the first tasks was therefore to find suitable partners for various aspects of the project. In a first step, Fraunhofer IESE was won as an external partner for the specification phase. With the help of the IESE team, topics such as requirements specification, context, user and task analysis, software risk analysis, initial architecture consulting and evaluation, usability engineering and the design of the graphical user interface were developed. After the specification phase, it quickly became clear that external support was also required for the implementation:  The successful cooperation with t2informatik began.

The Development Process

For the project, we proposed and introduced Scrum as the process model. In the first 6 months we occupied the role of ScumMaster. This part of our assignment included the training of Eckert & Ziegler BEBIG employees, the moderation of the meetings, the introduction and adaptation of the project management software in-STEP BLUE and the use of a taskboard oriented to Kanban. [Scrum, in-STEP BLUE, Taskboard]

Development of a test-driven multi-layer Architecture

The main focus was on the highest possible maintainability and safety of the system. We designed the software architecture of the WPF application according to the MVVM pattern. A clean layer separation and the use of code generators based on T4 templates as well as numerous unit tests ensured that all layers could be tested independently of each other. In addition, the CI Server Jenkins was configured, in particular the build processes were adapted and automated. [WPF, C#, .NET, T4 Templates, MVVM, NUnit, NSubstitute, Jenkins]

Development of the Communication Layer

To increase the maintainability of the system, the connection to the medical device was decoupled by interfaces. A separate implementation was realized as default for the behavior of the medical device based on C#. The extracted interface was used to operate and test the WPF application without a connected medical device. Unit tests were written against the interfaces that had to be met by both the reference implementation in C# and the implementation communicating with the medical device. Using the machine-to-machine protocol OPC UA, the communication to the medical device was realized with the help of a third-party library. As part of the analysis of the communication technology, a generator technology with CSV files and T4 templates was established, whereby the interface between the OPC UA client and the server interface can be completely generated. [OPC-UA, C#, .NET, NUnit]

Data Model and Database Upgrade

The data management of the software was described by an Enterprise Architect model and generated using XMI and T4 templates in entity classes. For this purpose, a migration component was developed with which the database schema including the data could be updated version secure and lossless. [NHibernate, C#, SQL, MS-SQL, Enterprise Architect]

Web Application for Device Management

A web application has been developed that can manage and export common data from the HDR Brachytherapy product family in a variety of ways. [Entity Framework, MS-SQL, C#, ASP.NET MVC]

Automatic Upgrade Mechanism

The system is able to update itself independently via an update package. The WPF application runs in a Windows kiosk mode, making it a self-contained, secure application that can update and restart the system. The resulting application was developed test-driven. It is generically extensible by a component model.

Creation of a PDF-A Generator

All system and customer reports must be generated in PDF-A format. For this purpose, a technology based on iTextSharp with XHTML/CSS, XML serialization of model data and XSL transformations was developed under the responsibility of Eckert & Ziegler BEBIG and extended by t2informatik for new reports. XSL templates make it very easy to create new reports, since common sections from both the XML serializations and the XSL transformations can be reused. [XML, XSLT, iTextSharp, NUnit, C#, .NET]

Execution of System Tests

All functional requirements specified in the functional specification had to be verified by system tests for each release of the product. For this purpose, templates for test protocols were created from the requirements and executed in an integrated system. In the case of extensions and/or changes to the requirements, the test protocols were adapted accordingly. [Requirements Management, Test Management, in-STEP BLUE]

Maintenance and Support

During the pilot phase, internal support staff were supported in difficult error analyses and inquiries from international customers were answered. Today we support Eckert & Ziegler BEBIG in the further care and maintenance of the system. We conduct code reviews, increase performance, migrate individual components and help implement customer requirements. [C#, .NET, B&R Automation, Visual Studio]

Transfer of Knowledge

The sustainable development of the product required coaching of the internal employees. These tasks included the introduction to WPF development, practices such as Clean Code, architecture compliance and the error analysis procedure. [C#, .NET, UML]