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17_SAP_LUW.md
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- [Bundling Techniques](#bundling-techniques)
- [Related ABAP Statements](#related-abap-statements)
- [Concepts Related to the SAP LUW](#concepts-related-to-the-sap-luw)
- [Notes on the SAP LUW in ABAP Cloud and RAP](#notes-on-the-sap-luw-in-abap-cloud-and-rap)
- [The SAP LUW in ABAP Cloud and RAP](#the-sap-luw-in-abap-cloud-and-rap)
- [Controlled SAP LUW](#controlled-sap-luw)
- [More Information](#more-information)
- [Executable Example](#executable-example)
@@ -279,7 +280,7 @@ The following concepts are related to the SAP LUW to ensure transactional consis
<p align="right"><a href="#top">⬆️ back to top</a></p>
## Notes on the SAP LUW in ABAP Cloud and RAP
## The SAP LUW in ABAP Cloud and RAP
A limited set of ABAP language features is available in ABAP Cloud ([restricted ABAP language version](https://help.sap.com/doc/abapdocu_latest_index_htm/latest/en-US/index.htm?file=abenrestricted_version_glosry.htm)).
The limitations include the fact that the above bundling techniques are not available. Note that the local update is enabled by default in ABAP Cloud. Find more information in this [blog](https://blogs.sap.com/2022/12/05/the-sap-luw-in-abap-cloud/).
@@ -292,6 +293,73 @@ There are RAP-specific [ABAP EML](https://help.sap.com/doc/abapdocu_latest_index
- [`ROLLBACK ENTITIES`](https://help.sap.com/doc/abapdocu_latest_index_htm/latest/en-US/index.htm?file=abaprollback_entities.htm): Resets all changes of the current transaction and clears the transactional buffer. The statement triggers `ROLLBACK WORK`.
- Find more information in the [ABAP cheat sheet about EML](08_EML_ABAP_for_RAP.md).
<p align="right"><a href="#top">⬆️ back to top</a></p>
## Controlled SAP LUW
- The *controlled SAP LUW* is an enhancement to the SAP LUW concept.
- It introduces a check mechanism to detect violations of [transactional contracts](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abentransactional_contract_glosry.htm) to guarantee transactional consistency.
- Such contracts specify which ABAP statements and operations are allowed and which are not allowed in a [transactional phase](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abentr_phase_glosry.htm).
- In this way, applications can be made more robust and the SAP LUW can be made more tangible.
- Violations that are detected result in a runtime error (or are logged).
- There are mainly two transactional phases: *modify* and *save*.
- In RAP, these two phases are set implicitly, and they are subdivided as follows (see more information in the EML cheat sheet and the RAP guide):
- *modify*
- [RAP interaction phase](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenrap_int_phase_glosry.htm)
- [RAP early save phase](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenearly_rap_save_phase_glosry.htm)
- *save*
- [RAP late save phase](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenlate_rap_save_phase_glosry.htm)
- Using the static methods `modify` and `save` of the `CL_ABAP_TX` class, you can activate the transactional phases explicitly.
- The controlled SAP LUW is automatically and implicitly supported by newer ABAP concepts such as RAP (i.e. the transactional phases are implicitly active when RAP handler methods are called), [background Processing Framework (bgPF)](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenbgpf_glosry.htm), and local consumption of [RAP business events](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenrap_entity_event_glosry.htm).
- Furthermore, transactional contracts define where (i. e. in which transactional phase) a [classified API](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenclassified_api_glosry.htm), such as a method of a class, can be used. The classifications start with `IF_ABAP_TX_...`, for example, `IF_ABAP_TX_SAVE`, and are, in the case of methods, typcially included as types in the local types of the class ([CCDEF include](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenccdef_glosry.htm), *Class-Relevant Local Types* tab in ADT). The classifications detail out and restrict the scope of use, so as not to use a classified API in phases where not allowed. Follow the links below for more information.
- Example of a classified API: Open the class `CL_BCS_MAIL_MESSAGE` (which is used for sending emails). In ADT, go to the *Class-Relevant Local Types* tab, and find classifications for methods, for example, the `send_async` method. Calling this method in the *modify* transactional phase results in a violation. You can also get information about the transactional contract using the F2 information in ADT. In the case of the method mentioned, choose F2 on `send_async` (`... cl_bcs_mail_message=>create_instance( ... )->send_async( ). ...`) to view the transactional contract information.
- Regarding the concrete restrictions and for more information, follow the links.
- Examples for violations, such as database modifications. They are only allowed in the *save* transactional phase because the data being processed in the *modify* phase may be inconsistent:
- Database modification (e.g. `MODIFY dbtab FROM @row.`) performed when the *modify* transactional phase is active.
- Database modifcation in a [RAP handler method](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenabp_handler_method_glosry.htm) implementation. Here, the *modify* transactional phase is active by default.
- Database modifcation in a [RAP event handler method](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenrap_event_handler_meth_glosry.htm) implementation when the *save* transactional phase has not been activated explicitly. Note: When RAP event handler methods are called, they are started in the *modify* transactional phase. Modifying a database right away there, without the activation of the *save* phase, means a violation.
- Calling a classified API in a phase where not allowed, such as `... cl_bcs_mail_message=>create_instance( ... )->send_async( ). ...` (classified with `IF_ABAP_TX_SAVE`) in the *modify* transactional phase.
- More information:
- [Controlled SAP LUW](https://help.sap.com/docs/abap-cloud/abap-concepts/controlled-sap-luw) in the SAP Help Portal
- ABAP Keyword Documentation (Standard ABAP):
- [Restrictions in Transactional Phases](https://help.sap.com/doc/abapdocu_latest_index_htm/latest/en-US/index.htm?file=abapinvalid_stmts_in_tx.htm)
- [API Classifications](https://help.sap.com/doc/abapdocu_latest_index_htm/latest/en-US/index.htm?file=abapapi_classification.htm)
- [Restrictions in RAP Handler and Saver Methods](https://help.sap.com/doc/abapdocu_latest_index_htm/latest/en-US/index.htm?file=abapinvalid_stmts_in_rap_methods.htm)
Example using `CL_ABAP_TX`:
```abap
...
"Activating the modify transactional phase
cl_abap_tx=>modify( ).
"The following database modification statement is not allowed in the
"modify transactional phase. In certain contexts, e.g. in ABAP Cloud,
"the runtime error BEHAVIOR_ILLEGAL_STMT_IN_CALL occurs.
MODIFY zdemo_abap_carr FROM TABLE @( VALUE #(
( carrid = 'XY'
carrname = 'XY Airlines'
currcode = 'EUR'
url = 'some_url' ) ) ).
...
"Activating the save transactional phase
cl_abap_tx=>save( ).
"In this phase, database modifications are allowed.
MODIFY zdemo_abap_carr FROM TABLE @( VALUE #(
( carrid = 'XY'
carrname = 'XY Airlines'
currcode = 'EUR'
url = 'some_url' ) ) ).
...
```
<p align="right"><a href="#top">⬆️ back to top</a></p>
## More Information
- [The RAP Transactional Model and the SAP LUW](https://help.sap.com/docs/SAP_S4HANA_CLOUD/e5522a8a7b174979913c99268bc03f1a/ccda1094b0f845e28b88f9f50a68dfc4.html) (Development guide for the ABAP RESTful Application Programming Model)
- [The SAP LUW in ABAP Cloud](https://blogs.sap.com/2022/12/05/the-sap-luw-in-abap-cloud/) (blog)