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Course materials may not be reproduced in whole or in part without the prior written permission of IBM. 5.1

Copyright IBM Corporation 2008

IMS Transaction Manager

Unit 5

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Objectives

Understand the goals and architecture of IMS/TM (Transaction

Management) Learn the LTERM concept and how it relates to messages,

message types and queues Learn how IMSGEN control blocks required for TM are coded

and maintained Know the how IMSGEN control blocks, PSB and MFS control

blocks are used in TM Understand the Master Terminal Operator and IMS terminal

commands Understand IMS system security, integrity and maintenance

functions

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z/OS

IMS/BATCH

Address Space

Application

DL/I Modules

Data Buffers

IMS/BATCH

Address Space

IMS/BATCH

Address Space

Application

DL/I Modules

Data Buffers

Application

DL/I Modules

Data Buffers

Database

(C)

Database

(A)

System

Log

Database

(B)

System

Log

System

Log

Multiple IMS Batch Address Spaces

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Goals of IMS/TM

Provide high-volume, rapid response transaction management

processing for application programs accessing IMS/DB database (full function and Fast Path) DB2 tables

Define a logical/physical terminal structure that supports Growth Change independence Usage of common resources Productivity

Support database management integration

Data integrity through two phase commit of unit of work Reliability/availability/serviceability (RAS) throughtransaction/database logging

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ONLINELOG

DATA SET

CORPORATE

DATABASESRECONMSG

QUEUE

z/OS

IMSCTLControl

Region

MESSAGE

SCHEDULING

LOGGING/

RESTART

DBRCRecovery

Control

DLISASDL/I

Subordinate

Address Space

MPRMessage

Processing

Region

BMPBatch

Message

Processing

IFPFastPath

Region

TELECOMMUN-

ICATIONS

LOG

CTL

DL/IACTION

MODULES

APPLPGM

APPLPGM

APPLPGM

USER

TERMINA LS

IMS/TM makes data available to the end-user...

MASTER

TERMINA L

IMS/TM Architecture

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IMS/TM Dependent Regions

Maximum of 999 dependent regions

Message Processing Regions (MPRs): Selective start-up at IMS initialization Processes "online" transactions from terminals IMSCTL automatically "schedules" application programs for execution to

process IMS/DB databases, or DB2 tables Many different application programs can process in a given MPR

throughout processing period

Batch Message Processing (BMP) regions: Started when JOB submitted by operations Runs one application-program to process queued transactions, IMS/DB

databases, and/or z/OS files Allows batch-type programs to process IMS queues and databases while

IMS/TM system is available

Interactive Fast Path (IFP) regions:

Bypass IMS/TM scheduling via Expedited Message Handler (EMH) For large transaction volumes that require fast response

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IMSCTL

(Control Region)DATA COMMUNICATIONS:

MPR

(Msg. Processing Region)

LOGICALTERMINAL

ABC

MESSAGES

APPLICATIONPROGRAM

'ANYPGM'

LOGICALTERMINAL

XYZ

PHYSICALTERMINAL

1

PHYSICALTERMINAL

2

PHYSICAL

TERMINAL

3

Logical Terminal (LTERM) Concept

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Transactions

Originate from terminal (most IMS/TM activity) Can originate from another application-program via "program-switch"

Message-switches

Allows terminals to communicate with each other

Commands

Mostly entered by MTO Some commands may be entered from user terminals

/ COMMAND-VERB (PASSWORD) text

1 2 n

LTERMnme (PASSWORD) text

1 8 9 18 19 n

TRANcode (PASSWORD) text

1 8 9 18 19 n

Message Types

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Message Type Examples

Transactions:

SALARY(XPSWD) 123456'Salary for John Doe (123456) is $xxx.xx'

ADDINV PART 9876 QTY=50'Inventory on 9876: 10-Speed Bicycle = 9950 units'

Message-SwitchesACTGTERM

ACCOUNTING DEPARTMENT MEETING AT 2:00PM

Commands

/checkpoint freeze

/start line 5 pterm 2

/change(zzzyyx) password 999888 to password 888999

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z/OS

All INPUT and OUTPUT messages are queued...

MESSAGEQUEUE

DATA SET(S)

IMS/TM IMS/MPR1 IMS/MPR2

QUEUE

BUFFERS

QUEUE

MANAGER

GET FROM

QUEUE

INSERT

TO QUEUE

A P P L

GET FROM

QUEUE

INSERT

TO QUEUE

A P P L

. . . . . .. . . . . .

Message Queue (1 of 2)

LOGICAL

TERMINAL

(LTERM)

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TRAN

XTRAN

Y

1. INPUT TRANSACTIONS are QUEUEd by:

MSG1 (LTERMA) X

MSG3 (LTERMX) X

MSG4 (LTERMQ) X

MSG7 (LTERMX) X

MSG2 (LTERMB) Y

MSG5 (LTERMZ) Y

MSG6 (LTERMA) Y

2. OUTPUT MESSAGES are QUEUEd by:

LTERMA LTERMB

RPL1 (X)RPL3 (X)

RPL2 (Y)

MESSAGE-QUEUE BUFFERS (Control Region)

MSG1 RPL3 RPL2 MSG5 MSG7

RPL1 MSG6

MSG2 MSG4 MSG3

MESSAGE

QUEUE

DATA SET(S)

Message Queue (2 of 2)

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PSBs for IMS Transaction Manager

PCB TYPE=TP

PCB TYPE=DB

PSBGEN...

TPAlternate response IOPCB.

Used to send a message.

DB Used to read or update a database - same as IMS db.

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APPLICATION PROGRAM:

MASK

MASK

MASK

(TP-)

IO-

PCB

ALT

IO-

PCB

DATA

BASE

PCB

LOGICAL

TERMINA L

ALTERNATE

LOGICAL

TERMINAL

CUSTOMER

ADDRESS PAYROLL

LOGICAL DATABASE STRUCTURE

LOGICAL

TERMINA L

LOGICALTERMINA

L

Logical Structures

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INVENTORY MENU

100

10

PART-NO: 200

INVPGM

INVENTORY ON-HAND :

100 99

200 789

10 1000

A. DEVICE INPUT FORMAT

(DIF)

D. DEVICE OUTPUT FORMAT

(DOF)

INVPGM 00100 00200 00010

B. MESSAGE INPUT DESCRIPTOR (MID)

(EDITED MESSAGE)

C. MESSAGE OUTPUT DESCRIPTOR (MOD)

(EDITED MESSAGE)

100 0099 200 0789 10 1000

APPL

PGM

ISRT

NXT=

MODNAME

MESSAGE

FO

RMATSERVICE

S

(MFS)

Message Format Service (MFS)

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PAYROLL MENU:

NAME:____________

SERIAL:___________

ADDRESS:_________

DEPT:_____________PF1=UPDTPF3=EXIT

/FORMAT PAYMENU

MFS Formatting a Screen

FORMATTING A SCREEN:

Using /FORMAT command:

No program is involved

Using Program-control: Format screen using output message from a program CALL 'CBLTDLI' USING ISRT IO-PCB IO-AREA PAYMENU

Message that is written to queue contains MOD name to be used to map aDOF (screen-format) name

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SF00 MSG TYPE=OUTPUT, SOR=(SFIL00, IGNORE),OPT=2,NXT=SFIN00,FILL=PT

MFLD REPLY, LTH=50,JUST=LMFLD SKILL, LTH=8, JUST=L

MFLD NAME,LTH=6, JUST=L

MSGEND

Creates

MOD...

SFIN00 MSG TYPE=INPUT,SOR=SFIL00,OPT=2,

NXT=SF00MFLD TRANCD,LTH=6,FILL=NULL

MFLD TYPESEG,LTH=1,JUST=L, FILL=C' '

MFLD SNE, LTH=18,JUST=L, FILL=C' '

MFLD DEGREE, LTH=1, JUST=L, FILL=C' '

MFLD SUBJECT, LTH=15, JUST=L,FILL=C' '

MFLD CDATE,LTH=4, JUST=L,FILL=C' '

MSGEND

Creates

MID...

MFS Creating Control Blocks

Creating MFS control blocks:

//TEST EXEC @MFS//SYSIN DD *

PRINT NOGEN

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Creates

DIF/DOF...

MFS - Source

SFIL00 FMT

SFIL00 DEV TYPE=(3270,2) ,FEAT=IGNORE,

PFK=(TRANCD,'CONVA '),

DSCA=X'00A0'

DIV TYPE=INOUT

DPAGE CURSOR=((5,7))

DFLD 'SKILL INVENTORY UPDATE',POS=(2,30),ATTR=(NUM,PROT,HI)

DFLD 'TYPE',POS=(5,2), ATTR=(NUM,PROT,HI)

TYPESEG DFLD POS=(5,7), LTH=1DFLD 'SKILL/EMPLOYEE/COURSE',POS=(7,2),ATTR=(NUM,PROT,HI)

SNE DFLD POS=(7,24),LTH=18

DFLD 'DEGREE',POS=(9,2),ATTR=(NUM,PROT,HI)

DEGREE DFLD POS=(9,9),LTH=1

DFLD 'SUBJECT',POS=(11,2),ATTR=(NUM,PROT,HI)

SUBJECT DFLD POS=(9,9),LTH=1

DFLD 'COMPLETION DATE',POS=(13,2),ATTR=( NUM,PROT,HI)

CDATE DFLD POS=(13,18),LTH=4

DFLD 'CURRENT SKILL',POS=(15,2),ATTR=(NUM,PROT,HI)

SKILL DFLD POS=(15,16),LTH=8

DFLD 'CURRENT NAME',POS=(15,25),ATTR=(NUM,PROT,HI)

NAME DFLD POS=(15,39),LTH=6

DFLD 'RESULT',POS=(17,2),ATTR=(NUM,PROT,HI)

REPLY DFLD POS=(17,9),LTH=50

DFLD 'USE PF KEY 1 TO BEGIN THE CONVERSATION',POS=(23,2)

FMTEND

END/*

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A system resources controller LTERM

that is the operational "hub" of IMS/TM...

COMMUNICATIONS

COMMUNICATION

LINES/NODES

PHYSICAL

TERMINALS

LOGICAL

TERMINALS

TRANSACTIONS AND

PROGRAMS

MESSAGEREGIONS

SYSTEM

STATUS

CHECKPOIN

T/ RESTART

DATABASEDUMP

andRECOVERY

z/OS system console is "back-up" to MTO console...

SCHEDULING INTEGRITY

LOGICAL

TERMINA L

MASTERTERMINAL

DATABASE(S)

Master Terminal Operator (MTO)

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Terminal Commands

MASTER Terminal: REMOTE Terminal:

/NRESTART "Normal"/ERESTART "Emergency"

/CHECKPOINT

/DISPLAY /SIGN ON USERID PAYROLL

/ASSIGN /SIGNOFF

/CHANGE /IAM LTERM PAYROLL

/STOP and /START NODE /LOCK LTERM PAYROLL

DATABASE

PROGRAMTRANSACTION

REGION

/BROADCAST NODE ALL /HOLD

PAYROLL DATABASE UNAVAILABLE /RELEASE CONV 004

UNTIL 2:00PM /EXIT

/RMLIST DBRC='DB DBD(DIVNTZ04) DBDS' /FORMAT PAYMENU

/TEST

/DBDUMP /EXCLUSIVE

/DBRECOVERY /RDISPLAY MASTER

/OPNDST /RCLSDST

/CLSDST

/MODIFY PREPARE

/MODIFY COMMIT

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SMU Supportended with

IMS V9

IMS Security

What Can be Secured?

Terminals, Passwords, USERID Sign-on Verification Transactions Databases (Logical and Physical) Commands

IMS Security Maintenance Utility (SMU) maintains a dual"matrix" for security:

Protects IMS Resources/Objects IMS-provided Internal Security

User-Written Exit Routines:

/SIGN ON Exit Routine (DFSCSGN0) Transaction Authorization Exit Routine (DFSCTRN0) Security Reverification Exit Routine (DFSCTSE0)

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P

A

Y

I

N

G

R

E

F

I

N

D

A

D

D

I

N

V

A

D

D

P

A

R

T

T

A

B

L

E

Q

D

L

E

T

I

N

V

V

E

N

D

O

R

D

D

I

S

B

U

R

S

R

E

P

L

I

N

V

S

A

L

A

R

Y

L

I

S

T

I

N

V

U

P

D

T

I

N

V

REC101

SAL102

INV105

INV106

INV107

1

11 1

1 1

1 1 1

1 1 1 1 1 1 1

TRANCODE

L

T

E

R

M

Terminal and Password Security (1 of 2)

LTERM-Transaction Code matrix:

Terminals can be restricted to designated applications

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TRANCODE

P

A

Y

I

N

G

R

E

F

I

N

D

A

D

D

I

N

V

A

D

D

P

A

RT

T

A

B

L

E

Q

D

L

E

T

I

NV

V

E

N

D

O

RD

D

I

S

B

U

RS

R

E

P

L

I

NV

S

A

L

A

R

Y

L

I

S

T

I

NV

U

P

D

T

I

NV

PSWD01

PSWD02

PSWD05

PSWD06

1

1

1

1

P

A

S

S

W

O

R

D

Terminal and Password Security (2 of 2)

Password-Transaction Code matrix

Designated applications can be assigned a "password"

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System Integrity Functions

Common Logging Facility:

Database changes, transactions, system status changes Automatic system checkpoints Based on system activity System Recovery and Emergency Restart

Database Recovery Control Similar to batch recovery operations

Program IsolationAutomatic backout for program ABENDs Data Sharing by multiple programs

Normal Restart Start with unprocessed input/output from previous execution

C L i F ilit

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OLDS5

OLDS4

OLDS3

OLDS2

RECON

3

RECON

2

z/OS

IMS/TMDBRC DLISAS

ControlRegion

DB Recovery

Control

DL/I Subordinate

Address Space

SLDS2

SLDS1

RLDS2

RLDS1

SYSTEM

LOG

DATA

SETS

RECOVERY

LOG

DATA

SETS

LOG ARCHIVE UTILITY

WADS

WRITE

AHEAD

DATA

SETS

RECON1

Buffers Buffers

OLDS1

Common Logging Facility

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Common Logging Facility (Cont)

Recording of IMS/DB and IMS/TM system activity:

"Before" and "After" images of changed DL/I segments System status via periodic checkpoints Input and Output messages are logged

Provides integrity and recoverability of DB/TM systems: Used for Dynamic Backout of failing transactions

Used for system "warm" and "emergency" restarts Used for database recovery Used for performance and accounting statistics

Log Write-Ahead (LWA): To guarantee database integrity, log records are physically written

before database physically written Only selected "events" qualify for this technique

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OLDS and WADS

Online Log Data Set (OLDS)

Contains log records needed for: Restart Recovery Backout: Batch and Dynamic

Consists of multiple data sets

Allows IMS/TM to continue logging when an "OLDS switch" occursbecause of the following: OLDS is full I/O error while writing to an OLDS Operator commands /DBR or /DBD

Written in a "wrap-around" manner Can be archived automatically to the System Log Data Set (SLDS)

Write Ahead Data Set (WADS): Contains committed log records not yet written to OLDS

Normally, only full blocks are written

May be used to "close" the OLDS in an emergency

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Database Recovery Control (DBRC)

TWO LEVELS OF CONTROL:

LOG-CONTROL, controller of IMS log data sets: Maintains information about OLDS status

e.g. ARCHIVE-NEEDED, AVAILABLE, ARCHIVE-IN-PROGRESS, NEXT-OLDS

2a. SHARE-CONTROL since IMS 6.1 includes RECOVERY-CONTROL functions of earlier releases can assist in database integrity and recovery

Database "registration" by database data set Monitors Database Image Copies (ICs), Change Accumulations (CAs), Recoveries

(DBRs) Automatic JCL generation of needed job-streams

2b. SHARE-CONTROL enables database sharing: Access-intent must be registered with a "share-level

Database-level sharing Intra- or inter-processor block-level sharing

There is no DBRC or IMS "parm" that determines Log-Control vs. ShareControl

Share Control is in effect for individual databases once they are"registered"

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"The RECON" for Log-Control (1 of 2)

Recovery Control Data Sets (RECON):

Automatic recording of information about: Online Log Data Set (OLDS) System Log Data Set (SLDS) Recovery Log Data Set (RLDS)

Generation of utility JCL via DBRC command for: Log Archive Log Recovery

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//DFSOLP00

//DFSOLP01

//DFSOLP02

OLDS 1

OLDS 3

STATUS: ARCHIVE SCHEDULED

STATUS: IN USE

STATUS: AVAILABLE

RECON

PRIOLD

SECOLD

PRISLD

SECSLD

PRILOG

SECLOG

.

.

.

ARCHIVE

JOB:

ARC001

SLDS1

RLDS1

OLDS 2

"The RECON" for Log-Control (2 of 2)

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DBRC Database "Registration" for Share Control

Advantages:

Records recovery-related information in RECON Example: which OLDS has log data for each database data set (DBDS)

registered with DBRC

Controls recovery of databases

Generates JCL for recovery-related utilities Used to select correct data sets to be used by Recovery and Image-

Copy Consolidates changes of log records

Saves time Eliminates errors

Register databases with DBRC commands once a database is registered, Share Control is in effect

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'GHU' DBR

SEGM-A

REPL-A

'GHU' DBR

SEGM-B

'GHU' DBR

SEGM-B

REPL-B

'GHU' DBR

SEGM-A

PROG-A PROG-B

Program Isolation

Program "Isolation" (PI) facility is the original IMS Lock manager:

Allows multiple online programs to process the same database forupdate while preserving integrity But not the same segment occurrence!

Dynamic Backout facility: Removes the effects of any programs that abnormally end (ABEND)

Eliminates partial updates; uncommitted updates are backed-out

Deadlock Detection:

PI selects "loser" transaction for "pseudo"-ABEND and dynamic back-out; re-schedules it later...

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Restart Checkpoint

Type: Selected:

COLD CHKPT 0

WARM CHKPT GeneratedAt Previous

Shutdown

EMERGENCY Last CHKPT

Written to Log

Checkpoint and Restart (1 of 2)

IMS uses its own CHECKPOINT processing

System-wide checkpoint is taken periodically based on volume of log-records generated

Restart is based on use of a CHECKPOINT which contains a "snapshot" of system control-blocks to log data set (OLDS)

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z/OS

IMS/TM DBRC DLISAS

MESSAGE

QUEUE(S)

RECON DATABASE(S)

Checkpoint and Restart (2 of 2)

1. z/OS System Failure

2. Stand-alone dump3. Restart z/OS operating system4. Emergency Restart IMS: Database backout of "in-flight" transactions

1. In-flight" transactions re-scheduled2. Message queue reconstruction3. Message transmission repositioning

5. Continue processing

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System

Application

TerminalNetwork

IMS Generation (IMSGEN)

IMSGEN MACROS

Macro Function

IMSCTRL System-wide parametersIMSCTF z/OS parametersMSGQUEUE Message Queue definitionsBUFPOOLS Control-block buffer-pools

DATABASE DatabasesAPPLCTN Applications/Programs (PSBs)TRANSACT Transactions

COMM Communications defaultsTERMINAL Physical TerminalsNAME Logical Terminals (LTERMs)

Online Macro changes through Online Change facility DATABASE APPLCTN TRANSACT MFS format Block

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Extended Terminal Option (ETO)

Optional (additional cost) Feature of IMS/TM

Terminals may optionally be defined outside of the IMSGENProcess.

Fewer IMSGENs Smaller and faster IMSGENs

Dynamic control block management Requires user sign on

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Database Recovery Facility (DRF)

Separately priced product/tool

Introduced at the time of IMS 7.1 as "Online Recovery Service" follow-on product DRF introduced in June, 2003

Recovery is initiated via IMS Commands Executed in parallel with other online IMS activity

A new function of the Control Region Timestamp recovery to allocation boundaries or any prior pointin time

Recover multiple DL/I database data sets and FP areas in asingle pass of the IMS log

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DBRC

RECON

DLI/SAS

IMS Control Region

Database Recovery Manager

Recovery Data

Manager

Fast Path Areas

DL/I DBDS

...

...

.........

LogDataSets

Change

Accum

ImageCopy

Components and Flow

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Components

Database Recovery Manager

Driven by the IMS Command Processor to process recovery relatedcommands Creates the Recovery Data Manager address space Establishes communication with the Recovery Data Manager Receives log data from the Recovery Data ManagerApplies updates to the database data sets and areas

Coordinates recovery termination and Database Recovery Facilityparticipation in IMS shutdown processing

Recovery Data Manager Started when the first recovery command is entered Restores image copies, if required, with change accumulation data, if

available Reads log data and processes records related to this recovery Merges log data into a recovery stream

DBRC Maintains recovery related informationAll resources required for recovery must be registered to DBRC Validates recovery initiation and results

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Recover Command

/RECOVER ADD

Identifies the database data sets and areas Builds a 'recovery list'

/RECOVER REMOVE Eliminates database data sets and areas from the 'recovery list'

/RECOVER START Initiates recovery

/RECOVER STOPAborts recovery

/RECOVER TERMINATE

Cleans up Recovery Data Manager address space

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IMS Related Products

DB2 (External Subsystems DBMS) with IMS/TM

CICS with IMS/DBCTL IMS Queue Control Facility (QCF) Manage IMS Message Queues

Screen Definition Facility II (SDF II) Help to build MFS control blocks

Automatic code generators:

CSP Cross-System Product supports: CICS/ESA with IMS/DB

IMS/TM to access DL/I DBs and/or DB2 tables

ADF Application Development Facility II

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Unit Summary

IMS/TM supports the RAS (Reliability, Availability &

Serviceability) characteristics for application transactionprocessing programs

LTERMs isolate messages, message types, queues andprogram processes from physical terminal characteristics

IMSGEN, PSB and MFS control blocks are used in differentaspects of TM

Master Terminal Operation capabilities and IMS terminalcommands are available to control and maintain transactionsystems

IMS system security, integrity and maintenance functions exist ETO and DRF are additional cost options/tools that extend the

capability of IMS

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