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IMS DBIMS DB Day 1Day 1

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AgendaAgenda

y Hierarchical and Other Data Models

y IMS Overview

y

IMS and Data Management Conceptsy IMS Environments

y IMS Terminology

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IMSIMS the world depends on itthe world depends on it

y IMS, IBM's premier transaction andhierarchical databasemanagement system.

y Chances are you using IMS when

You Turn on Light Get a business loan

Make a telephone call Process accounting records

Use your ATM card Rent a car

Conduct international business/banking Use corporate data bases

y Most Corporate Data is Managed by IMS

Over 95% of Fortune 1000 Companies use IMS

IMS Manages over 15 Billion GBs of Production Data

Over 50 Billion IMS transactions run in a day

IMS Serves Close to 200 Million Users a Day

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IMSIMS A Glance at HistoryA Glance at History

y IBM designed IMS with Rockwell and Caterpillar starting in 1966 for theApolloprogram. IMS's challengewas to inventory the very large bill ofmaterials (BOM) for theSaturnV moonrocket andApollo space vehicle

y The first "IMS READY" message appeared on an IBM 2740 terminal in Downey,California, on 14 August 1968

y

Over theperiod, many interestingdevelopment activities happenedwhich includes IMSsupporting the Java programming language, JDBC, XML, and, since late 2005, Webservices.

y Vern Watts was IMS's chief architect formany years. Mr.Watts

y

joined IBM in 1956 andworked at IBM's Silicon Valleyy development labs until his deathApril 4, 2009. Hehad

y continuously worked on IMS since the 1960s.

y IMS is reportedly IBM's highest revenue softwareproduct, and it continues to grow

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Flat File StructureFlat File Structure Data ModelData Model

Adatabasewith a single table is called a flat file structure.

Good only forextremely simpledatabases andnot practical for

most business applications.

Whats Wrongwith it ??? Data More Redundant

Data Integrity

Data Dependency

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NetworkModelNetworkModel

The network model is a databasemodel conceived as a flexibleway of

representing objects and theirrelationships

Where thehierarchical model

structures data as a tree ofrecords,witheachrecordhaving oneparent

record andmany children, thenetwork model allows each

record to have multiple parent

and child records

Why it did not succeed??

Firstly, IBM chose to stickto thehierarchical model with their

establishedproducts such as IMS and DL/I.Secondly, it was eventually displaced by therelational model, which

offered a higher-level, moredeclarative interface

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Hierarchical ModelHierarchical Model

Ahierarchical data model is a data model inwhich thedata is organized into a tree-like

structure.

The structure allows representinginformation usingparent/childrelationships:

eachparent canhavemany children buteachchild only has oneparent (also known

as a 1:many ratio ).

All attributes of a specificrecord are listedunder anentity type

Themost recognized and usedhierarchical

databases is IMS developed by IBM

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Relational ModelRelational Model

(RDBMS - relational databasemanagementsystem) Adatabase based on therelational model

developed by E.F. Codd.

Arelational database allows thedefinition ofdatastructures, storage andretrieval operations and

integrity constraints. In such a database thedataandrelations between them are organized in tables.

A table is a collection ofrecords andeachrecord in a tablecontains the same

fields.Properties of Relational Tables:

Values AreAtomic

Each Row is Unique

ColumnValues Are of the Same Kind

Each Column Has a UniqueName

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Hierarchical, Relational and ObjectHierarchical, Relational and Object

OrientedOriented

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Hierarchical, Relational or Object OrientedHierarchical, Relational or Object Oriented

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IMSIMS A Database Management SystemA Database Management System

y A Database is a collection of interrelateddata items,stored once and organized in a form foreasy retrieval.

y

A Database Management System is a collection ofprograms for storing organizing, selecting, modifying,

andextractingdata from a database.

y

IMS DB is organizedhierarchicallyy To optimize storage andretrieval

y To ensure integrity andrecovery

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IMSIMS A Transaction Management SystemA Transaction Management System

y A Transaction is therequest andexecution of a set ofprograms, performing administrative functions andaccessing a shareddatabase on behalf of a user

y A Transaction Management Systemcreates, executes,

andmanages Transaction ProcessingApplications forscalability to high transaction loads

y IMSTM continues providing leadership

To efficiently managenetwork, message, application,anddata processing

To ensurehighperformance, availability, security,

andrecovery

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IMS and Data Management ConceptsIMS and Data Management Concepts

Data Redundancy: the samedata element was often located in

several places within the sameprocessing system

Data Integrity: If values for thedata element arechanged in somefiles, but not in others.The integrity of thedata is jeopardized

Social Security numberName (last, first, initial)

SalaryPay period

DeductionsExemptionsAbsences

Marital statusSex

Dependents

Job codePerformance evaluations

DepartmentAllergies

VisitsTreatmentsMedications

Centralized

DatabaseApproach

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Common

Social Security number

Name (last, first, initial)

Address (street, city, state, zip)

Payment

Salary

Pay Period

Deductions

Exemptions

Absences

Personal

Marital status

Sex

Dependents

Job code

Performanceevaluations

Medical

Department

Allergies

Visits

Treatments

Medications

Data Dependency : whenever a change indata structure or in accessmethod occurs , applicationprogramneeds to berevised as it is custom

Designed according to format andphysical location ofdata they process

Normalization

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Data Security : Unauthorized user access to the various IMSressources, transactions, data bases, etc. is controlled by RACF

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Data Logging : During IMS execution, all informationnecessary torestart the system in theevent ofhardware or software failure is

recorded on a system logdata set.

Data Recovery : There are also a number of tools and features

availablewith IMS to help inrecovery scenarios:

Extended Recovery Facility (XRF), for use inhaving a hot standby

systemready to take overwithin the same site.

Remote Site Recovery (RSR), for use incomplete sitedisasters, to

recover thecomplete IMS system(s) very quickly at another site.

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IMS EnvironmentsIMS Environments

Primary ProductsIMS/DB - Databasemanagement, logging & recovery

IMS/TM - Interactive online functions, transactiondriven

Product Implementations

DB/DC

DBCTLDCCTL

The two batch environments are:

DB batch, which is generated from DB/DC and DBCTL class system

generations.

TM batch, which is generated from DCCTL class systemgenerations.

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IMS DB/DC EnvironmentIMS DB/DC Environment

The DB/DC environment is composed of a control region anddependentregions that might includemessageprocessingprogram (MPP), batch

messageprocessing (BMP), and IMS Fast Pathprogram (IFP) regions.

DBCTL behaves in the samemanner as IMS DB in a DB/DC environment,

but it does not support user terminals, a master terminal, ormessagehandling.

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The DBCTL EnvironmentThe DBCTL Environment

DBCTL behaves in the samemanner as IMS DB in a DB/DC environment,but it does not support user terminals, a master terminal, ormessage

handling.

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TheThe DCCTLDCCTL EnvironmentEnvironment

The DCCTL environment is an IMS

Transaction Manager subsystem that

has no databasecomponents.

A DCCTL environment is similar tothe "DC" component of a DB/DC

environment.

Theprimary difference is that a

DCCTL control region owns no

databases anddoes not service DL/Idatabasecalls

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The DBBatch EnvironmentThe DBBatch Environment

DB Batch is the batchenvironment

that is generatedduring DB/DC or

DBCTL systemgenerations.

The DB Batchenvironment has a

single address space that

contains both IMS code and theapplicationprogram.

DB Batch applicationprograms haveaccess to DL/I and GSAM databases.

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TerminologyTerminology

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TerminologyTerminology

y Segment & Fields Segment is the smallest unit of information that IMS

transfers to & fromdatabase.

A segment may contain one ormore fields.

y Segment Type and Segment Occurrences Segment TYPE is a category ofdata while segment

OCCURRENCE is one specific segment of aparticular type.

y Parent & Child Segments A Segment higher in a path is a PARENT.

A Segment lower in a path is a CHILD.

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TerminologyTerminology contd.contd.

y Path

Chain ofdependent segments types under the

root.

Neednot becomplete to the lowest level ofthedatabase.

y Level

Position of a Segment within its Path.

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y Twins

Multiple occurrences of a segment type under

the same immediate Parent.

Segments must belong to same Parentsegment occurrence, not just same segment

type.

y

Siblings A sibling is any segment that has the same

parent as another segment, but is of a

different segment type.

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y Database Record

Each occurrence of theroot segment plus all

segment occurrences that are subordinate to

it make up onedatabaserecord.y Database

Collection of all databaserecords.

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y Hierarchical Structure Arrangement of the segments of a database

record into paths ofdata.

y

Key/Sequence Field KEY field is a fieldwithin a Segment, selected to

identify the occurrence of the segment.

Used by IMS to maintain segments in ascendingsequence.

y Search Fields Used to search for a segment, without the

segment being sequenced on that field.

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Q & A?Q & A?

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ThankYouThankYou

ims db - day 1

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