Tobias Schulz

For the native app of a data-intensive ERP application, an efficient and reliable real-time synchronization between the app and the backend was to be realized.

Via a WebSocket-based protocol newly developed in C#, very large amounts of data (over 1 million records in over 120 tables) can be kept synchronized efficiently and without user interaction for mobile apps.

The constantly maintained WebSocket connection enables server-side pushing of data to all devices within a few seconds in case of changes to individual records.

The protocol also allows the execution of C# scripts on the devices for remote maintenance and diagnostic purposes, as well as monitoring of device parameters such as operating system version, storage space utilization, or errors that occurred on the devices.

It was implemented with a backend based on ASP.NET Core (.NET Core 3.1, later .NET 6) and a client library for integration into Xamarin apps as well as WPF-based desktop applications.

The client required ticket and order systems with identical business logic on various technical platforms and form factors.

Therefore, a system was to be designed and developed for a ticket system framework that would allow the business logic to be described as declaratively and language-independently as possible.

The data sources for the fields, the forms, and the events triggered by status changes of the processes were described using a Lisp-like scripting language.

Interpreters were developed for both the web (server-side via PHP/Laravel) and for within native apps (using C#/C++/Xamarin) to execute the scripting language on the respective platform.

To enable the creation of shared BDD / integration tests for both a Xamarin app and web-based backend applications, a Skia-based backend for Xamarin Forms was created that can be accessed via an API similar to Selenium. Since no real smartphones are needed for the tests, the tests could be executed more easily and reliably on a Linux server.

The Xamarin.Forms backend renders into a framebuffer to enable video/screenshot creation during tests (especially in case of errors).

From PHP / Behat, BDD tests can thus be executed in Gherkin / Cucumber syntax, where each test instruction is executed either in the browser or in the Xamarin app, depending on the context.