IMS DB - Day 1
Transcript of IMS DB - Day 1
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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
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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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IMS and Data Management ConceptsIMS and Data Management Concepts
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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IMS and Data Management ConceptsIMS and Data Management Concepts
Data Security : Unauthorized user access to the various IMSressources, transactions, data bases, etc. is controlled by RACF
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IMS and Data Management ConceptsIMS and Data Management Concepts
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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TerminologyTerminology contd.contd.
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.
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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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TerminologyTerminology contd.contd.
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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TerminologyTerminology contd.contd.
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