One of the features of the Qt IVI Generator is the possibility to create remote backends that utilize the QtRemoteObjects module. A remote backend may be an independently running process, even on a separate host machine, that can be accessed by multiple clients, or frontends. Such frontends are e.g. the main infotainment system UI, different applications running within the UI or mobile devices.

Motivation

The purpose of having remote backends is to enable the distribution of functionality and the sharing of information. This may be between multiple processes and even between multiple host machines. Separate processes improve the overall reliability of a complex system and make it possible to separate computationally intensive code from the UI code. Additionally, remote backends can be accessible by multiple frontend points, be it the central UI, separate applications or even mobile devices or third party applications. Combined with the automatic generation of code and uniform feature loading of QtIvi, the development of distributed features comes with a minimal development overhead and interchangeability and transparency on the UI code side.

Code Generation

The remote objects generator produces client side code as a QtIvi backend plugin and a remote server stub. The client is generated using the backend_qtro template and the s erver using the server_qtro template. Both the plugin and the server contain generated c++ code and an intermediate .rep -file that is further processed by Qt’s replica compiler to produce the actual source and replica classes.

The generated plugin is loaded and used as any other QtIvi plugin and is interchangeable with any other backend implementation with the same API. As all method calls over QtIvi feature interfaces are asynchronous, the use of a remote backend is similar to any other type of backend.

The generated plugin is buildable and usable as it is, and does not require further changes by the developer. The task of the developer will be then to implement the intended functionality at the server side. To support getting started with the server, there is a generated class that initializes the connection. All connection parameters to the plugin and to the server are passed currently over a config file, either in a default location or at an user specified path.

For a steb-by-step introduction to remote backends, see the Remote Backend Example.