topic Re: Synchronous Vs ASynchronous in Application Development and Automation Discussions

Synchronous Vs ASynchronous

Former Member — Thu, 26 Apr 2007 11:24:23 GMT

Hi friends, can any one explain ?

what are Synchronous and ASynchronous updates in BDC ?

what is the differences between Synchronous and ASynchronous updates ?

pls dont give any links for other sites, explain it clearly,

full points for clear explanations....

Thanks and Regards

Vijaya

Re: Synchronous Vs ASynchronous

Former Member — Thu, 26 Apr 2007 11:27:30 GMT

Hi,

Synchronous Update : This means say if u have 10 records to update and the processing is going on in a loop the Synchronous update will wait till each update is actually done in the data base and then it will move on the next record's updation.

Asynchronous : In This mode, the updates are lined one after the other and the system doesn't wait for the updates to actually happen. These updates are then triggered by an internally scheduled job which then actually updates the data in the databse.

Regards,

Himanshu

Re: Synchronous Vs ASynchronous

Former Member — Thu, 26 Apr 2007 11:28:08 GMT

HI Laxmi,

I will take a n example of call transcation statement.

In general a call transaction will update the database tables of that transaction.

If you specify the update mode as Synchronous, then the control would not come to the calling program until and unless all the related tables are updated completed.

In Asynchrouns updates, the control wil not wait for the data base tables to be updated.

Obviously it is faster.

Regards,

Ravi

Re: Synchronous Vs ASynchronous

former_member196299 — Thu, 26 Apr 2007 11:33:00 GMT

Hi ,

Here you go with the answers in detail:

Synchronus data processing is that in which the program calling the update task waits for the update work process to finish the update before it continues processing.

In Asynchronus update the callng program does not wait for update work process to finish the update and continues as normal.

A BDC done with sessions is always synchronus.

A BDC with call transaction is by default asynchronus

unless you define it explicitly as

call transaction 'XXXX' ...... update 'S'.

( If you donot define update option it is defaulted to "A" ).

The update method is of importance when one transaction locks data which may be required by a subsequent transaction . The subsequent transaction will fail if data is locked from previous one. An example would be you are creating sales order for same material in succession ( with asynchronus update ). Quite likely that some of transactions would fail due to material locked.

For large volume of data Call Transaction will be faster but you have no restart capability here. Suppose from 1000 transactions 100 fails . You will have to run the BDC program again exclusing the ones which wrere successful. However with session method you have the option to process the error transactions again in SM35 . So if you are sure that errors will not occur use call transaction else use session method.

Few more informations:

In batch session interface: - Asynchronous processing means Transfers data for multiple transactions - Synchronous database update means during processing, no transaction is started until the previous transaction has been written to the database.

In CALL TRANSACTION: - Synchronous processing means Transfers data for a single transaction. Synchronous and asynchronous database updating both possible The program specifies which kind of updating is desired. Separate LUW for the transaction The system performs a database commit immediately before and after the CALL TRANSACTION USING statement.

Reward all useful answers !

Thanks

Ranjita

Message was edited by:

Ranjita Kar

Re: Synchronous Vs ASynchronous

Former Member — Thu, 26 Apr 2007 11:35:12 GMT

Hi,

In Synchronous updating, the called transaction (CT) waits until all the updates have been completed. So processing is slower than with synchronous updating. The called transaction can however report any updating errors to the program, which makes error analysis/correction easier.

In Asynchronous updating, the called transaction does not wait until the database has been updated, it simply forward the updates to the SAP update service. This usually speeds up the CT program. This processing mode is NOT recommended for large data sets as the called transaction does not receive a completion message from the update module. The calling CT program therefore cannot tell if the transaction has been successfully completed. You should use the updating administration function (transaction SM13) to determine whether updating was terminated early. The error analysis /correction functions for are less helpful than with synchronous updating.

Re: Synchronous Vs ASynchronous

Former Member — Thu, 26 Apr 2007 11:56:51 GMT

Hi Viajaya Laxmi,

I can go the easy way..Just check below...

#1 : what are Synchronous and ASynchronous updates in BDC ?

PS: Session Methods use Synchronous updates and Call Transaction Methods use Asynchronous updates.

Session method: The records are not added to the database until the session is processed. sy-subrc is not returned. Error logs are created for error records. Updation in database table is always Synchronous.

Call Transaction method: The records are immediately added to the database table. sy-subrc is returned to 0 if succesful. Error logs are not created and hence the errors need to be handled explicitly. Updation in database table is either Synchronous or Asynchronous.

#2 : what is the differences between Synchronous and ASynchronous updates ?

Asynchronous Update –The program does not wait for the work process to finish the update. Commit Work.

Synchronous Update – The program wait for the work process to finish the update. Commit Work and Wait

I hope this would be clear enough ....

Reward points if this is useful.

Cheers,

KumarR

Re: Synchronous Vs ASynchronous

Former Member — Thu, 26 Apr 2007 19:50:16 GMT

Hi,

Synchronous Update:

In synchronous update, you do not submit an update request using CALL FUNCTION... IN

UPDATE TASK. Instead, you use the ABAP statement COMMIT WORK AND WAIT. When the

update is finished, control passes back to the program. Synchronous update works in the same

way as bundling update requests in a subroutine (PERFORM ON COMMIT). This kind of update

is useful when you want to use both asynchronous and synchronous processing without having

to program the bundles in two separate ways.

The following is an example which you could use in asynchronous update:

DATA CONTEXT_NAME LIKE RS33F-FRMID.

CONTEXT_NAME = 'DOCU_TEST1'.

...

CALL FUNCTION 'CONTEXT_BUFFER_DELETE' IN UPDATE TASK

EXPORTING

CONTEXT_ID = CONTEXT_NAME

EXCEPTIONS

OTHERS = 0.

....

COMMIT WORK.

Asynchronous Update:

A typical R/3 installation contains dialog work processes and at least one update work process.

The update work processes are responsible for updating the database. When an ABAP program

reaches a COMMIT WORK statement, any function modules from CALL FUNCTION... IN

UPDATE TASK statements are released for processing in an update work process. The dialog

process does not wait for the update to finish. This kind of update is called asynchronous update.

Regards,

Bhaskar