Package 

The package concept achieves better structuring of ABAP software by providing a tool to ensure or track the decoupling of software. Each development object, for example a report, global class, data element, or table, is assigned to a package. These packages are viewed as capsules whose content is invisible from the outside. Interaction with the package's content can only be accomplished through those development objects that are exposed in particular package interfaces of the respective package. A package may have a number of interfaces to better support different usage types in a clear manner. These enable you to restrict possible clients from accessing certain packages. With this approach, a package can grant to “friend packages” more extensive access to its content than other packages would have.

Package P exposes OBJ through a Package Interface

 

The properties of packages include:

·        Nesting: A package may belong to a parent package

P2 is a subpackage of P1

·        Dependency Control List: a package defines dependencies to other packages by using a DCL.

·       Client Interfaces

Furthermore, the package determines the transport properties of the development objects contained in it – for example, whether the objects can be exported from the system at all, or, if they can be exported, what are the target systems (through the assignment to a transport layer).

Packages are classified as Structure Packages, Main Packages and Development Packages. Structure and Main packages form the upper two levels of the package hierarchy. The root packages are referred to as structure packages. They only contain subpackages and no development objects.

The second level is made up of main packages. These are similar to ordinary packages, but are protected by particular authorization checks and mechanisms. The reason for this is because they effectively determine the software component's external interface, which means that changes to this interface need to be done with special care in order to avoid invalidating the software component's clients.

All development objects belong to Development packages. Development packages are contained within Main packages or Structure packages.

The software components used in production and delivery of SAP software consist of package hierarchy trees that are a collection of Structure, Main and Development packages.