ABAP Keyword Documentation → ABAP Programming Guidelines → Architecture → Data Storage
Using Shared Objects
7.31 | 7.40 | 7.54
Access to shared objects is regulated by lock mechanisms. The individual locks are stored as administrative information with the area instances in the shared memory and are set and evaluated when they are accessed using area handles.
Shared buffer and exclusive buffer are suitable application scenarios for shared objects.
The access to shared objects should be wrapped in loader and broker classes.
How locks work depends on how shared objects are used as follows:
- Scenario 1 - Use as a shared buffer
- Scenario 2 - Use as an exclusive buffer
General shared memory programming is not possible. The current lock logic does not enable you to set specific locks for the following requirements:
- Many parallel reads and writes
- Frequent writes
- Split into modifiable and non-modifiable areas
Although the lock logic makes the first two points technically possible, they are not practical because most accesses would be rejected.
It is recommended that application programs do not access the shared objects memory directly. Instead reads on the shared objects should be wrapped in a wrapping class, whose methods are accessed by the individual programs. The area constructor class can be used as the wrapping class, for example.
Wrapping has the following advantages:
- Central administration of an area in the shared memory
- An application program does not need to worry about area handles and locks.
- Central administration of locks
- Option to implement central authorization checks