COMMITMENT CONTROL IN ADVANTAGE PLEX for

DB2/400

Yolanda Scholtz18 November 2002

Session - 4E

15:15 - 16:00

EDGE EMEA Conference - 2002

2

Agenda

• Overview • Setting Up Commitment Control for DB2/400• Across Advantage Plex and Advantage 2E• Switching Commitment Control On or Off • Considerations• Commitment Control Errors• Additional Notes• Questions

3

• Operations to run optimally

• Reliable data within Information Systems

• Improving / ensuring data integrity

• Reduce time spent on correcting data

Need & Benefits

4

• Commitment Control is a database facility that enables a group of database changes to be treated as a single transaction, regardless of the files being changed.

Thus you can ensure that either ALL or NONE of the changes are performed.

Definition

5

IllustrationParent

Child 1 Child 2

Calls

Updates

Updates Updates

ERROR

CommitChanges

6

IllustrationParent

Child 1 Child 2

Calls

Updates

Updates UpdatesRollbackOccurred

7

Setting up Commitment Control

Parent

Commit / Rollback

Child 1

Child 2

Child 3

8

• Setting Up Commitment Control for DB2/400– Framework– Implementation

• Logic in the Patterns

• Commitment Control Functions

• Inheritance

• Development Standards

• Business Functions

Setting up Commitment Control

9

Framework

• Commit Group– Parent– Child– None

• Commit / Rollback

• Journal OS/400 Physical Files

10

• A Commit Group is a group of one or more data access functions within which all database changes are treated as a single transaction.

• Define a commit group using the triple

FNC Commit SYS verb

None Parent Child

Commit Group

11

FNC Commit SYS None

None is the default value if no commit property is specified. It means that the function will not be part of a commit group.

Commit groups should be specified only where they are necessary, otherwise they serve only to decrease the performance of the function.

None

12

FNC Commit SYS Parent

This server function belongs to a commit group and will be generated with the code that starts commitment control (unless another parent in the commit group has already started it).

A Commit group must have at lease one parent.

Parent

13

FNC Commit SYS Child

This server function belongs to a commit group.

A commit group can have one, many, or no child functions.

Child

14

• Commit and Rollback statements in action diagram – If not, the results will be unpredictable - any

database changes will remain uncommitted until another program executes a commit or rollback operation.

Commit / Rollback

15

• Ensure that the OS/400 physical files being updated are being journalled.

• For information on journal management, refer to the AS/400 Advanced Backup and Recovery Guide.

Journal Physical Files

16

• Pattern– Function Shell

• Functions– Commit Start– Commit End

• Inheritance

• Business functions

Implementation

17

• Function Shell changes :– Local Variable and fields

• Commitment– Control Status– Control On

– Meta coding to interrogate triples of functions to determine if Commitment Control is required

– Initialise– Terminate

• Go SubCommit

– Additional Subroutine(Commit)– Rollback message

Pattern

18

FunctionShell

19

FunctionShell

20

FunctionShell

21

Purpose:

To ensure that STRCMTCTL command is executed (this is done automatically due to triple commit SYS parent)

Coding:

None

Commit Start

22

Commit Start

23

• Purpose:

– To ensure that ENDCMTCTL command is executed (this is done automatically due to triple commit SYS parent)

– To execute COMIT / ROLLBACK statement. (This is done exclusively in program)

Commit End

24

Commit End

25

• The FunctionShell is inherited by ALL functions

• Commit function inherits from main function

• Data Access function Commit - – auto created in model through inheritance– scoped to data access function

Inheritance

26

• Naming Convention– MyEntity.MyFunction Commit

• Syntax• Model Editor

• Action Diagram

Development Standards

27

Model Editor

MyFunction comprises MyFunction Commit

MyFunction Commit is a MyFunction

MyFunction Commit Commit Sys Child

28

Action Diagram

Condition calls to functions

Coding may be copied to the desired place in the action diagram where a function call is done.

29

• BENEFITS of Common Sequence– Remove monotony of coding the conditional

call construct– Eliminate errors in coding the conditional call

construct– To ensure standardization

Development Standards

30

• Process Group– Set returning status (as it is always normal)

• Control Commit / Rollback – via Commit Subroutine– Commit Subroutine always in Terminate

Action Diagram

31

• Either function (Plex or 2E) may contain the main commit point

• Both Plex and 2E functions may be specified as Child/Slave within the same Commit Group

• Only one Parent/Master may be defined

Across Advantage Plex and 2E

32

Across Advantage Plex and 2E

Advantage Plex Advantage 2ECommit control option None None

Parent MasterChild Slave

Function / Command Commit / Rollback Commit

33

As easy as

1... Set Triple COMMIT SYS (parent / none)

2... Gen & Build this main function

3... Start / End Journalling on affected

OS/400 files

On / Off Switch

34

• Performance

• Replace default data access functions– In EDITDETAIL, EDITDIALOG, ect.

• Make function a Parent or Child

• Undefine the deleterow

• Replace with conditional coding

Reason: the default deleterow is automatically called in these functions (inheritance).

Considerations

35

• If Client is parent– set Panel Properties<Window Type>=dialog

• to prevent another MDI child being executed simultaneously

– test returned status and set returning status• To ensure that rollback occurs if data access fails

– Call Commit Start in initialization section• STRCMTCTL auto executed if server parent

– Call Commit End for Commit / Rollback• auto executed if server parent

Considerations

36

• Implementation timing– During vs After Development

• Identification of Business Functions

• Journal OS/400 Physical Files

• Development effort

• Test entire system

• Room for Error

• Impact on system maintenance and support

• Model Administration

• Integration impact

Considerations

37

• unexpected Return Code = 01217.– Member EntityPF not journaled to journal *N

• Function check. CPF8351 unmonitored by FTN0001S at statement 845, instruction X'0179’.– Commitment control already active.

Commitment Control Errors

38

• Can retrieve data from file during process• Can update same record twice• Cannot make changes to record externally• Terminate only executed on close• Commit desired business function, row or grid

• Files may be journalled and updated by functions NOT under commitment control

• If the function is under commitment control the files being referenced for update MUST be journalled

Additional Notes

39

Questions

40

Questions