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lock objects

hi all,

What is a Lock Objects?

Thanks in advance.......

vasu...

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6 Answers

  • Posted on Aug 22, 2007 at 01:44 AM
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    Former Member
    Posted on Aug 22, 2007 at 10:18 AM

    Hi,

    Lock objects are used to synchronize access to the same data by more than one program.

    General information about the lock mechanism.

    You can synchronize access by several programs to the same data with a logical lock mechanism. This lock mechanism fulfills two main functions:

    A program can tell other programs which data records it is just reading or changing.

    A program can prevent itself from reading data that is just being changed by another program.

    When accessing data records, the records just being edited by other programs can be identified by the entry in the lock table. Such an entry for the lock must define a number of fully specified key fields, that is either a value is passed for the key field or this field is locked generically.

    To set locks, a lock object must be defined in the ABAP Dictionary. When this lock object is activated, two function modules (see Function Modules for Lock Requests) are generated with the names ENQUEUE_ are generated from its definition to set and release locks.

    You can find information about the activation flow in the activation log, which you can display with Utilities ® Activation log. If errors occurred during activation, the activation log is displayed immediately

    Regards,

    Sudha S

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    Former Member
    Posted on Aug 22, 2007 at 10:22 AM

    Hi VASU

    see the doc on lock objects

    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.

    You have to use these function module in your program.

    check this link for example.

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

    tables:vbak.

    call function 'ENQUEUE_EZLOCK3'

    exporting

    mode_vbak = 'E'

    mandt = sy-mandt

    vbeln = vbak-vbeln

    • X_VBELN = ' '

    • _SCOPE = '2'

    • _WAIT = ' '

    • _COLLECT = ' '

    • EXCEPTIONS

    • FOREIGN_LOCK = 1

    • SYSTEM_FAILURE = 2

    • OTHERS = 3

    .

    if sy-subrc <> 0.

    • MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO

    • WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.

    endif.

    Normally ABAPers will create the Lock objects, because we know when to lock and how to lock and where to lock the Object then after completing our updations we unlock the Objects in the Tables

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

    purpose: If multiple user try to access a database object, inconsistency may occer. To avoid that inconsistency and to let multiple user give the accessibility of the database objects the locking mechanism is used.

    Steps: first we create a loc object in se11 . Suppose for a table mara. It will create two functional module.:

    1. enque_lockobject

    1. deque_lockobject

    before updating any table first we lock the table by calling enque_lockobject fm and then after updating we release the lock by deque_lockobject.

    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 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

    Check these links -

    lock-objects

    lock-objects

    lock-objects

    reward points to all helpful answers

    kiran.M

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  • author's profile photo
    Former Member
    Posted on Aug 22, 2007 at 10:24 AM

    Hi,

    purpose: If multiple user try to access a database object, inconsistency may occer. To avoid that inconsistency and to let multiple user give the accessibility of the database objects the locking mechanism is used.

    Steps: first we create a loc object in se11 . Suppose for a table mara. It will create two functional module.:

    1. enque_lockobject

    1. deque_lockobject

    before updating any table first we lock the table by calling enque_lockobject fm and then after updating we release the lock by deque_lockobject.

    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 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

    Check these links -

    lock-objects

    lock-objects

    lock-objects

    Regads,

    Priyanka.

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  • author's profile photo
    Former Member
    Posted on Aug 22, 2007 at 11:42 AM

    Lock objects are used to synchronize access to the same data by more than one program.

    General information about the lock mechanism.

    You can synchronize access by several programs to the same data with a logical lock mechanism. This lock mechanism fulfills two main functions:

    A program can tell other programs which data records it is just reading or changing.

    A program can prevent itself from reading data that is just being changed by another program.

    When accessing data records, the records just being edited by other programs can be identified by the entry in the lock table. Such an entry for the lock must define a number of fully specified key fields, that is either a value is passed for the key field or this field is locked generically.

    To set locks, a lock object must be defined in the ABAP Dictionary. When this lock object is activated, two function modules (see Function Modules for Lock Requests) are generated with the names ENQUEUE_*reward for useful answers*</b>

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    Former Member
    Posted on Aug 22, 2007 at 03:12 PM

    Hi Vasu

    To keep it simple, when you are updating the contents of some Database table, you dont want others to work on that table as this may lead to inconsistencies in the values returned. So as a precautionery measure you want to lock this particular or a particular key of that table so that the data cannot be accessed until your operation is completed. For this purpose you will use lock objects.

    Suppose you want to insert some data into SPFLI table. So you would say.

    CALL FUNCTION 'ENQUEUE_ESSPFLI'.

    IF SY-SUBRC EQ 0.

    • Now it is locked. No one else can access spfli.

    INSERT SPFLI FROM WA.

    ENDIF.

    CALL FUNCTION 'DEQUEUE_ESSPFLI'. " Now it is unlocked

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