Get Example source ABAP code based on a different SAP table
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Transaction Mode Since the transaction service of the Object Services is connected to classic transaction processing or is built on SAP LUWs, it is important that a program can specify whether it is working with classic or object-oriented transactions. Therefore, we need to introduce the term 'transaction mode'. This can be specified once for each program. Each program working with persistent objects has a transaction mode that is defined either explicitly or implicitly when the Object Services are initialized. Each program also has a 'top level transaction' (a transaction object whose reference can be obtained with method IF_OS_TRANSACTION_MANAGER~GET_TOP_TRANSACTION) while it is working with persistent objects. The top level transaction is responsible for updating the persistent objects. The program's transaction mode is also the transaction mode of the top level transaction and can be queried with method IF_OS_TRANSACTION~GET_MODES in parameter E_EXTERNAL_COMMIT. There are two transaction modes:
Compatibility mode The compatibility mode (E_EXTERNAL_COMMIT is OSCON_TRUE) permits persistent objects to be used within classic SAP-LUWs. The statement COMMIT WORK must be specified explicitly in the program to commit changes. Implicit methods of the persistence service are called when a program is executed to commit the changes made to persistent objects. When using the persistence service in compatibility mode, the system always implicitly starts one update process, which also deletes any locks in the update task.
Object-oriented transaction mode The object-oriented transaction mode (E_EXTERNAL_COMMIT is OSCON_FALSE) is used to write new fully object-oriented applications without having to worry about the statement COMMIT WORK. In object-oriented transaction mode, COMMIT WORK is triggered when the method END is called for a top level transaction. The COMMIT WORK statement is not allowed in an object-oriented transaction. The transaction mode can be defined and the top level transaction created as follows:
If in a program, method CL_OS_SYSTEM=>INIT_AND_SET_MODE has not been executed prior to the first access to the persistence service, the service starts it with the default values that set the transaction mode to compatibility mode and the update mode to asynchronous. A top level transaction is implicitly created and started at this time to handle the persistent objects of the program. All other transactions that are started in the program with IF_OS_TRANSACTION~START are subtransactions of the top level transaction that is running in compatibility mode. This makes it possible to work in classic ABAP programs with persistent objects without having to explicitly worry about the transaction mode. An example can be found under Creating a Persistent Object.
If the method CL_OS_SYSTEM=>INIT_AND_SET_MODE is executed before the persistence service is accessed in a program for the first time, the transaction mode can be set explicitly to compatibility mode or object-oriented mode by passing the values OSCON_TRUE or OSCON_FALSE to the parameter I_EXTERNAL_COMMIT. Since the static constructors of the persistence service are usually executed at the beginning of a processing block, the event LOAD-OF-PROGRAM or the constructor of an application class can be used, for example, to call CL_OS_SYSTEM=>INIT_AND_SET_MODE. A program that was not started as OO transaction can thus be executed as an object-oriented transaction. In object-oriented transaction mode, the first transaction that is started in the program with IF_OS_TRANSACTION~START is a top level transaction, whereas in compatibility mode, the top level transaction is always created implicitly.
If the OO transaction model field is selected when an object-oriented transaction is created in ABAP Workbench, the transaction mode of the corresponding program is automatically set to object-oriented (CL_OS_SYSTEM=>INIT_AND_SET_MODE is executed implicitly with the relevant parameters) when the transaction is called. The first transaction that is started in the program with IF_OS_TRANSACTION~START is a top level transaction.
Update Modes At the end of a top level transaction (with COMMIT WORK in compatibility mode or method IF_OS_TRANSACTION~END in object-oriented mode), the transaction service updates the changes to persistent objects in the database. Internal update function modules are started implicitly at this time. The way that the update function modules are executed is specified; by the initialization of the Object Services with method CL_OS_SYSTEM=>INIT_AND_SET_MODE, or after starting the top level transaction (one-off specification) with method IF_OS_TRANSACTION~SET_MODE_UPDATE. Since CL_OS_SYSTEM=>INIT_AND_SET_MODE can only be called once for each program, IF_OS_TRANSACTION~SET_MODE_UPDATE makes it possible to change an update mode that was set implicitly. Input parameter I_UPDATE_MODE with type OS_DMODE can be used for both methods to set the update mode. Possible values are:
OSCON_DMODE_DEFAULT, OSCON_DMODE_UPDATE_TASK for asynchronous updates
0OSCON_DMODE_UPDATE_TASK_SYNC for synchronous updates
OSCON_DMODE_LOCAL for local updates
OSCON_DMODE_DIRECT for saving directly OSCON_DMODE_LOCAL and OSCON_DMODE_UPDATE_TASK_SYNC cannot be specified in compatibility mode, since there they can be set by the ABAP statements COMMIT WORK AND WAIT and SET UPDATE TASK LOCAL. When an object-oriented transaction is created in ABAP Workbench, the initial update mode of the top level transaction is defined through selection of the relevant radio button.
Example The following example assumes that the program is running in object-oriented transaction mode. This requires either the transaction to be flagged as an OO transaction in transaction maintenance (the OO transaction model must be marked) or the method INIT_AND_SET_MODES to be called before a persistent object is accessed (the parameter I_EXTERNAL_COMMIT must be set to OSCON_FALSE). Only then does the method END trigger an update. If the above does not apply, the program is in compatibility mode, where the statement COMMIT WORK must be specified explicitly after a transaction ends. data TM type ref to IF_OS_TRANSACTION_MANAGER. data T type ref to IF_OS_TRANSACTION. ... TM = CL_OS_SYSTEM=>GET_TRANSACTION_MANAGER( ). T = TM->CREATE_TRANSACTION( ). ... TRY. T->START( ). ... 'Change persistent Objects T->END( ). CATCH CX_OS_ERROR. ... ENDTRY.
