This documentation is specific to the Control and Simulation division at the Aerospace Engineering department of the Delft University of Techology, the place where DUECA was created. However, it might offer some inspiration to others who want to organise their software repositories for DUECA projects. It is currently (2024) a work in progress, and we have transitioned our relevant old CVS-based projects to git+CMake based projects.

Facilitating module borrowing

Facilitating software re-use was one of the design goals for the DUECA middleware. In DUECA, two types of re-use are dominant, the first is by "borrowing" modules from other DUECA projects, and the second form is by adopting DCO objects, often implicitly by borrowing a module.

Sharing and borrowing code led to the following good:

Common modules that are re-used in many projects.
Commonly used DCO objects are available that create a more or less stable interface between different borrowed modules (notably across joystick input and control loading devices).

Some less favorable aspects are:

DCO objects are still being borrowed from otherwise long forgotten student projects, no longer maintained but ubiquitous across many newer projects.
Hacks are sometimes needed to squeeze the data in the current DCO objects. Changes in DCO objects are limited, to not affect large numbers of projects.
Some projects still use obsolete variants of generic support modules (e.g., the "joystick" and "multi-stick"), which are no longer maintained.
Some developers tended to copy rather than borrow modules, resulting in projects having copied modules with no or little changes; leading also to problems in maintenance of these projects.

With the transition from a CVS-based repository, which combined all projects in one, to git-based repositories, with information on the git url's for each software module, the DUECA projects of our group no longer need to be all concentrated in the same location. This leads to some choices for the use of repository and the relation between projects.

Design and working methods

To promote the re-use of general, curated DUECA modules, modules that are commonly used in different projects can be organised in a separate group on the repository server, at

@gitlab.tudelft.nl:ae-cs-dueca-base/

.

Git also offers better means to keep software variants in different branches, and merge the results together. This enables quicker incorporation of student work into a "reference" version of a project. The proposed working method for students who continue with a project from a predecessor or a reference project, would then be to clone the project to a repository under their own username, and perform work on one or more branches that are clearly identifyable as belonging to the student. After completion of the project, the branches may be merged back into the reference project. When the capabilities of the reference project can be enhanced by the student's work, the student's branch may be merged into the main project, otherwise the branch might be kept as a separate branch in the main project.

That still leaves us, for the time being, with a number of projects converted from the CVS repository to git, which are not "cleaned up" yet. The following division in groups is proposed for the DUECA software on gitlab.tudelft.nl. That implies that the software can be found at a url

://gitlab.tudelft.nl/<<group>>/<<Project>>.git

, or as

@gitlab.tudelft.nl:<<group>>/<<Project>>.git

(with write access) where <<group>> is the group's name, but all in lower case, and <<Project>> is the DUECA project name; these may be mixed, lower or upper case.

Group/Repository	Purpose and approach
AE-CS-DUECA-base	Generic base projects, providing services like motion filtering, control device IO, outside visual images, etc. These projects are generally maintained by Control and Simulation staff. They are not used as projects in themselves, rather the modules in these projects are commonly borrowed by a multitude of other projects.
AE-CS-DUECA-active	Working projects that are kept active on the simulation facilities, such as simulations now also used for demonstration or testing.
AE-CS-DUECA-ftis	Projects for the Flight Test Instrumentation and fly-by-wire system.
AE-CS-DUECA-archive	Finished (student) projects, kept as reference for future projects, but generally not actively maintained on the simulation facilities.
AE-CS-DUECA-yard	Older projects, resulting from the current transition from CVS to git, that are needed to run some of the active, older or current projects. The yard needs cleaning up, and with time the DCO objects and sometimes modules borrowed from these projects are moved into base projects, while, if applicable, the projects themselves are moved to the archive.
AE-CS-DUECA-students	When working on their graduation projects, students receive a fork from an existing project in base or archive, or start a new, blank project. A staff member will create the project, and assign access to the student. The project name will indicate which student is working on the project. After completion of the project, the result is added to the archive or active group, or merged back into the donating project as a separate branch.

In addition, a number of dueca projects are open source and published on GitHub. These can be found at git@github.tudelft.nl:dueca/, the section Shortened URL's for multiple base groups describes how to set-up your environment variables for quick access.

The page on Policies describes how policy support in dueca-gproject might support automated changes to project code.