topic Re: Lock Objects in Application Development and Automation Discussions

Lock Objects

Former Member — Tue, 10 Apr 2007 09:57:04 GMT

Hii All-

First question:

Can anyone explain in detail the types of lock objects available?? their purpose??

After creating the lock in SE11, do we specifically use Enqueue and Dequeue function modules in the program to lock and unlock the tables??? Suppose, I create the lock and activate using SE11 and do not use the function modules, what will happen?

Second question: Difference between SAP Memory and ABAP Memory in detail.

Rewards Definite

M A

Re: Lock Objects

Former Member — Tue, 10 Apr 2007 09:59:19 GMT

Hi Ahmed,

Lock objects are use in SAP to avoid the inconsistancy at the time of data is being insert/change into database.

SAP Provide three type of Lock objects.

- Read Lock(Shared Locked)

protects read access to an object. The read lock allows other transactions read access but not write access to

the locked area of the table

- Write Lock(exclusive lock)

protects write access to an object. The write lock allows other transactions neither read nor write access to

the locked area of the table.

- Enhanced write lock (exclusive lock without cumulating)

works like a write lock except that the enhanced write lock also protects from further accesses from the

same transaction.

You can create a lock on a object of SAP thorugh transaction SE11 and enter any meaningful name start with EZ Example EZTEST_LOCK.

Use: you can see in almost all transaction when you are open an object in Change mode SAP could not allow to any other user to open the same object in change mode.

Example: in HR when we are enter a personal number in master data maintainance screen SAP can't allow to any other user to use same personal number for changes.

Technicaly:

When you create a lock object System automatically creat two function module.

1. ENQUEUE_<Lockobject name>. to insert the object in a queue.

2. DEQUEUE_<Lockobject name>. To remove the object is being queued through above FM.

http://help.sap.com/saphelp_nw04/helpdata/en/cf/21eea5446011d189700000e8322d00/content.htm

GO TO SE11

Select the radio button "Lock object"..

Give the name starts with EZ or EY..

Example: EYTEST

Press Create button..

Give the short description..

Example: Lock object for table ZTABLE..

In the tables tab..Give the table name..

Example: ZTABLE

Save and generate..

Your lock object is now created..You can see the LOCK MODULES..

In the menu ..GOTO -> LOCK MODULES..There you can see the ENQUEUE and DEQUEUE function

Lock objects:

http://www.sap-img.com/abap/type-and-uses-of-lock-objects-in-sap.htm

http://help.sap.com/saphelp_nw04s/helpdata/en/cf/21eea5446011d189700000e8322d00/content.htm

Match Code Objects:

http://help.sap.com/saphelp_nw2004s/helpdata/en/41/f6b237fec48c67e10000009b38f8cf/content.htm

http://searchsap.techtarget.com/tip/0,289483,sid21_gci553386,00.html

See this link:

http://www.sap-img.com/abap/type-and-uses-of-lock-objects-in-sap.htm

SAP memory is a memory area to which all main sessions within a SAPgui have access. You can use SAP memory either to pass data from one program to another within a session, or to pass data from one session to another. Application programs that use SAP memory must do so using SPA/GPA parameters (also known as SET/GET parameters). These parameters can be set either for a particular user or for a particular program using the SET PARAMETER statement. Other ABAP programs can then retrieve the set parameters using the GET PARAMETER statement. The most frequent use of SPA/GPA parameters is to fill input fields on screens

ABAP memory is a memory area that all ABAP programs within the same internal session can access using the EXPORT and IMPORT statements. Data within this area remains intact during a whole sequence of program calls. To pass data

to a program which you are calling, the data needs to be placed in ABAP memory before the call is made. The internal session of the called program then replaces that of the calling program. The program called can then read from the ABAP memory. If control is then returned to the program which made the initial call, the same process operates in reverse.

http://www.sap-img.com/abap/difference-between-sap-and-abap-memory.htm

Regards,

Priyanka.

Re: Lock Objects

Former Member — Tue, 10 Apr 2007 10:00:25 GMT

Refer

2. http://www.sap-img.com/abap/difference-between-sap-and-abap-memory.htm

Regards,

Santosh

Re: Lock Objects

Former Member — Tue, 10 Apr 2007 10:01:50 GMT

Hi,

you have to use enqueue and dequeue FMs.otherwise no use of creating the lock object in se11.

regards,

bharat.

Re: Lock Objects

Former Member — Tue, 10 Apr 2007 10:15:17 GMT

SAP memory is a memory area to which all main sessions within a SAPgui have access. You can use SAP memory either to pass data from one program to another within a session, or to pass data from one session to another. Application programs that use SAP memory must do so using SPA/GPA parameters (also known as SET/GET parameters). These parameters can be set either for a particular user or for a particular program using the SET PARAMETER statement. Other ABAP programs can then retrieve the set parameters using the GET PARAMETER statement. The most frequent use of SPA/GPA parameters is to fill input fields on screens

ABAP memory is a memory area that all ABAP programs within the same internal session can access using the EXPORT and IMPORT statements. Data within this area remains intact during a whole sequence of program calls. To pass data

types of lock objects

There are two types of lock in the R/3 System:

Shared lock

Shared locks (or read locks) allow you to prevent data from being changed while you are reading it. They prevent other programs from setting an exclusive lock (write lock) to change the object. It does not, however, prevent other programs from setting further read locks.

Exclusive lock

Exclusive locks (or write locks) allow you to prevent data from being changed while you are changing it yourself. An exclusive lock, as its name suggests, locks an application object for exclusive use by the program that sets it. No other program can then set either a shared lock or an exclusive lock for the same application object.

Lock Duration

When you set a lock, you should bear in mind that if it remains set for a long time, the availability of the object to other transactions is reduced. Whether or not this is acceptable depends on the nature of the task your program is performing.

Remember in particular that setting too many shared locks without good reason can have a considerable effect on programs that work with database tables. If several programs running concurrently all set a shared lock for the same application object in the system, it can make it almost impossible to set an exclusive lock, since the program that needs to set that lock will be unable to find any time when there are no locks at all set for that object. Conversely, a single exclusive lock prevents all other programs from reading the locked object.

At the end of an SAP LUW, you should release all locks. This either happens automatically during the database update, or explicitly, when you call the corresponding dequeue function module. Locks that are not linked to a database update are released at the end of the SAP transaction.

For SAP standard tables it is already available. For any Ztable which you will be using to update or insert enrtries through a program and have doubts that this may be updated through other transactions as well, you need to create lock objects using the keys.You can do these throught SE11.

Again in your program before database insertion or deletion, perform ENQUEUE an dDEQUEUE of the lock object accordingly.

hope this will clear ur doubt

regards

ravish

plz reward if helpful

Re: Lock Objects

Former Member — Tue, 10 Apr 2007 10:15:28 GMT

Mohammad,

Lock objects are use in SAP to avoid the inconsistancy at the time of data is being insert/change into database.

SAP Provide three type of Lock objects.

- Read Lock(Shared Locked)

protects read access to an object. The read lock allows other transactions read access but not write access to

the locked area of the table

- Write Lock(exclusive lock)

protects write access to an object. The write lock allows other transactions neither read nor write access to

the locked area of the table.

- Enhanced write lock (exclusive lock without cumulating)

works like a write lock except that the enhanced write lock also protects from further accesses from the

same transaction.

You can create a lock on a object of SAP thorugh transaction SE11 and enter any meaningful name start with EZ Example EZTEST_LOCK.

Use: you can see in almost all transaction when you are open an object in Change mode SAP could not allow to any other user to open the same object in change mode.

Example: in HR when we are enter a personal number in master data maintainance screen SAP can't allow to any other user to use same personal number for changes.

Technicaly:

When you create a lock object System automatically creat two function module.

1. ENQUEUE_<Lockobject name>. to insert the object in a queue.

2. DEQUEUE_<Lockobject name>. To remove the object is being queued through above FM.

Lock objects:

http://www.sap-img.com/abap/type-and-uses-of-lock-objects-in-sap.htm

http://help.sap.com/saphelp_nw04s/helpdata/en/cf/21eea5446011d189700000e8322d00/content.htm

Create lock object.

GO TO SE11

Select the radio button "Lock object"..

Give the name starts with EZ or EY..

Example: EYTEST