Get Example source ABAP code based on a different SAP table
GUIDELINE 5.25
Using the Shared Memory
ABAP_BACKGROUND The shared memory of an application server is an highly important medium for buffering data with the goal of high-performance access. For this purpose, you can use the shared memory as follows:
To implicitly store data from database tables temporarily using SAP buffering, which can be determined when defining the tables in the ABAP Dictionary
To explicitly store data clusters in the cross-transaction application buffer using the EXPORT TO SHARED MEMORY or EXPORT TO SHARED BUFFER statements
To explicitly handle (data) objects stored there using shared objects, which are generated using the AREA HANDLE addition of the CREATE OBJECT or CREATE DATA statements
ABAP_RULE Implement the explicit buffering in the shared memory using shared objects Work with shared objects to explicitly use the shared memory for cross-program data buffering. The appropriate application scenarios are shared buffer and exclusive buffer. The access to shared objects should be wrapped in loader and broker classes.
ABAP_DETAILS For explicit access to the shared memory, shared objects (CREATE AREA HANDLE) provide the following advantages compared to the cross-transaction application buffer (SHARED MEMORY, SHARED BUFFER):
You can store any number of (data) objects, including their mutual interdependencies.
You can use (data) objects in the shared objects memory just like objects in the internal session. Technically, the shared objects memory can be considered an extension of the internal session during the time, the memory is bound to it.
Multiple programs can simultaneously access the same memory area without having to copy data to their own internal session. Scenarios in which you can use shared objects efficiently include the following:
Usage as a shared buffer A shared buffer contains a large data set to which many users have read access but which is changed rarely and is usually provided by a single program.
Usage as an exclusive buffer An exclusive buffer contains data that are accessed by only one program but that is maintained for various programs across transaction boundaries. You should not use the shared memory for different purposes, if, for example this results in many modifying accesses of parallel users, as the current locking concept does not support this. You should encapsulate the access to the shared memory in specific classes, and application programs should access the shared memory via these classes only. Normally, there are two classes, which you can also combine into one class:
A loader for creating and changing area instances
A broker for read access to area instances Such wrapping ensures the following:
Central management of the internal session#s connection to the shared objects memory and the corresponding locks
Central exception handling and respective fallback strategies (for example, if the shared object#s memory overflows, you can ensure that objects in the internal session are used without the using program having to be notified of this).
Potential authorization checks This makes the application program more legible, more robust, and easier to maintain.
Bad example The following source code shows how an internal table index_table , which has been formatted elsewhere and buffered in the cross-transaction application buffer, is imported to a program. To store it locally, a local data object is required. You can carry out such tasks more efficiently if you use shared objects. 'Get index page from data cluster IMPORT index_html = index_html FROM SHARED MEMORY docutables(...) ID ... ASSERT sy-subrc = 0.
Good example The following source code shows how an internal table index_table , which has been formatted elsewhere and buffered in the shared objects memory, can be accessed within program. By calling a get method, the corresponding broker ensures that its root attribute refers to a shared object that contains the table. You then do not require a local data object to access the internal table in the program. 'Get index page from shared memory cl_docu_tables_broker=>get_index_table( ). ASSERT cl_docu_tables_broker=>root->index_html IS NOT INITIAL.
