Community Question
What are Interfaces in AL Programming?
Share knowledge. Learn from experts. Build together.
Question
Interfaces in AL programming provide a way to define a contract that specifies what functionality a class must implement without defining the implementation itself. This supports abstraction and makes Business Central extensions more modular, maintainable, and easier to test.
An interface can define methods that implementing codeunits or other supported AL types must provide. Different implementations can then follow the same contract while providing their own business logic.
Interfaces are particularly useful when developing extensible Business Central solutions where the implementation may need to vary depending on configuration, business requirements, or integration scenarios.
Answers
Interfaces in AL (Application Language) provide a contract that defines a set of methods an implementing object must provide, without specifying how those methods are implemented.
This supports abstraction, loose coupling, extensibility, and testability in Dynamics 365 Business Central development.
For example, a business application might need to process payments through different providers. Instead of tightly coupling the application to one payment provider, developers can define an interface such as:
interface "Payment Processor"
{
procedure ProcessPayment(Amount: Decimal): Boolean;
}
Different implementations can then provide their own payment-processing logic.
Why are interfaces important?
1. Loose coupling
Business logic depends on a contract rather than a specific implementation.
2. Extensibility
Different implementations can be introduced without significantly changing the consuming code.
3. Testability
Developers can substitute implementations when testing business logic.
4. Maintainability
Responsibilities are separated, making larger solutions easier to manage.
5. Reusability
The same interface can be used by multiple components.
A typical architecture could be:
Business Logic → Interface → Implementation A / Implementation B
Interfaces are particularly valuable in Business Central extensions where functionality may need to vary by customer, configuration, localization, integration provider, or business scenario.
In short, an AL interface defines what a component must do, while the implementation defines how it does it.
Your Answer
Login required
Please login to participate in this discussion
and post your answer.