Which tier does a custom wrapper fall under?

A custom wrapper in the context of an SAP application's architecture typically falls under Tier 2. In the three-tier architecture commonly used in SAP systems, this tier is associated with the application layer, which is responsible for processing business logic and enabling communication between the user interface and the database.

The custom wrapper serves as an intermediary that encapsulates business logic, often simplifying interactions with underlying software components or services. By doing this, it promotes better code organization, reusability, and separation of concerns within the application. This is critical for maintaining and developing applications, as it allows for more structured and manageable code.

In contrast, other tiers serve different purposes. The first tier often pertains to the presentation or user interface layer, while the third tier is focused on the data storage or database layer. Any additional tiers beyond these generally relate to extended services or integrations, which are not the primary focus of a custom wrapper. Thus, understanding the tier classification is essential for effective architectural design and application development within SAP ABAP environments.