If logic is destined for multiple environments during the development phase, it's prudent to transfer shared code to an independent project. This augments code organization, with all projects accessing the shared code equally. Three primary methods to enact this rule are:

• External Project

This relates to an independent DLL library that others can incorporate as a pre-assembled component. However, this specialized method is still widely used in many development situations. It's ideal when the assembly code is written once and remains consistent. But, as code frequently evolves, when shared code changes are required, predicting impacts on other projects becomes challenging.

• File Link

Files from one project can be referenced in another project. While the file exists physically just once, it appears as a standard project file in multiple projects. This approach is better than its predecessor because it lets you rebuild the entire solution and run tests immediately after changes. However, there's a drawback: each file must be added individually. It can be tedious, especially in larger projects. Sometimes, the original project might fail to build due to certain incompatibilities. Even if the library DLL assembly isn't crucial, its alerts can generate undesired and often unnecessary notifications.

The DRY Principle in the Context of MS Dynamics 365 Backend Development - Solution Explorer

The DRY Principle in the Context of MS Dynamics 365 Backend Development - File Link

• Shared Project

This unique type of project in Visual Studio primarily serves as an auxiliary and is utilized by other projects. Such a project cannot add assembly references. Instead, these references are derived from the final project. Furthermore, it cannot add files. This project is not compiled and doesn't produce its assemblies. Its code integrates into the target projects as if it were originally part of them. A clear advantage of this approach is that you don't have to add each file individually to every project.

The DRY Principle in the Context of MS Dynamics 365 Backend Development - Shared Project