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Data Modeling A Retrospective


Finkelstein, Martin. Top-down approach. The Early Years Leading Edge ' ... James Martin a major influence. The 1980s Leading Edge. Prototyping ... – PowerPoint PPT presentation

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Title: Data Modeling A Retrospective

Data Modeling A Retrospective
  • April 2002

The Early Years - Practice
  • Data as a by-product of function (W. Inmon)
  • No data modeling as we know it
  • Data requirements defined by interfaces (user and
  • Data storage driven by screens, interfaces and
    physical DB (hierarchical DB or flat files).
  • Massive, paper-based methodologies
  • Text-based requirement definition
  • Monolithic, repetitive, ambiguous, fixed

The Early Years Leading Edge
  • Object Techniques
  • Simula I (Nygaard Dahl, 1965)
  • Used initially for simulation
  • No general acceptance in industry
  • Data Theory
  • Normalization (E. F. Codd, 1970)
  • Relational data base concepts developed
  • Oracle (1977), IBM System/R (1978), SQL (1982)
  • Bottom-up approach
  • Entity Relationship Diagrams
  • Finkelstein, Martin
  • Top-down approach

The Early Years Leading Edge
  • Classical Structured Analysis
  • Functional models are primary focus
  • Data Flow Diagrams
  • Data still in context of function
  • Emphasis on current state models
  • Little distinction between logical and
  • Data Structure Diagrams (DeMarco, Gane and
  • No capability to model temporal dimension
  • Emphasis on conversion of an arbitrary set of
    data structures into third normal form (Yourdon)

The Early Years Leading Edge
  • Modern Structured Analysis adds
  • Entity Relationship Diagrams (ERD) for static
    data modeling
  • State transition diagrams for time dependences
  • Event partitioning for middle-out instead of
    strictly top-down function modeling (McMenamin
    Palmer, 1984)
  • Distinction between logical (or conceptual or
    essential) models and physical models

The Early Years Leading Edge
  • Structured Programming and Design
  • Started at code level (programming)
  • Edsgar Dijkstra (1968)
  • Eventually expanded to structured design
  • Sought to make code more maintainable and promote
    code reuse (encapsulation)
  • Parallel initiative to Structured Analysis, but
  • Did not address data modeling

The 1980s - Practice
  • Cut and Paste data design using 1970s data
    structure common
  • Little change in many organizations
  • Focus on large systems, complicated interfaces,
    and reporting (not data)
  • Static data models using ERDs and Codds
    principles begin to be used
  • Structured Analysis more widely accepted, merged
    with Structured Design

The 1980s Leading Edge
  • Methodologies
  • Comprehensive, deliverables-based
  • Move from paper forms to CASE tools
  • Structured Analysis and Design is basis
  • Integrates graphical models into deliverables
  • Many similar methodologies
  • Information Engineering (Finkelstein Martin)
  • Dependent on CASE tools

The 1980s Leading Edge
  • CASE Tools
  • Closely allied to a methodology
  • Mechanized creation of graphical models
  • Automated some model quality checks
  • Segmented the development cycle
  • Upper Lower and Full CASE tools
  • COBOL code generation
  • Major tools implement Information Engineering
  • ADW (KnowledgeWare), IEF (Texas Instruments)
  • James Martin a major influence

The 1980s Leading Edge
  • Prototyping
  • Mock up of physical implementation
  • Usually throw-away since tools differed from
    production system tools
  • Extension of earlier practice of designing system
    from user interface
  • Often used as short-cut from requirements to
    design and code
  • Object-Orientation
  • C (1984)

The 1990s - Practice
  • Information Engineering accepted
  • Deliverables-based methodology
  • Relational data modeling
  • CASE tools used with varying degrees of success
  • CASE tools become more specialized
  • Microsoft Office as a CASE tool
  • Throwback to 1970s techniques
  • Y2K reinforces status quo

The 1990s Leading Edge
  • RAD (Rapid Application Development)
  • Originally applied to development once
    requirements were known
  • Timebox development
  • Requirements from workshops or focus groups (JAD)
  • Abbreviated project lifecycle
  • Prototyping to identify features requirements,
    demonstrate something tangible
  • Prototype becomes the system
  • Little or no design
  • Reuse of software components

The 1990s Leading Edge
  • Object Orientation
  • CASE tools provided major impetus
  • OOD, OOP and OO DBMS
  • OOA
  • Unified data and function
  • Extended OOD into analysis space
  • Class models, state transition models, sequence
  • UML (Gooch, Rumbaugh, Jacobson)
  • Unification of multiple OO approaches
  • Major step in gaining acceptance of OO
  • Originated in design and coding, weak in business
  • Java (1995)

The 1990s Leading Edge
  • Data Warehouse
  • "a copy of transaction data specifically
    structured for query and analysis (Kimball)
  • First major data-centered initiative
  • New data modeling techniques
  • Dimensional models, star joins (Kimball)
  • Arose from prior efforts for reporting and
    Management Information
  • Emphasis on data transformation
  • Data quality becomes important
  • Metadata important for information retrieval

The 1990s Leading Edge
  • Frameworks and Patterns
  • Applicable to different parts of lifecycle
  • Generic industry models (data and function)
  • Models for specific subject areas, like Party
  • Models for a particular use of data, e.g. Data
  • Design patterns in O-O, followed by analysis and
    organizational patterns and frameworks
  • Framework is a set of cooperating classes that
    make up a reusable design for a specific class of
  • Zachmann Framework for entire development process

The 1990s Leading Edge
  • Business Rules
  • Attempt to isolate most frequently-changing
    aspect of a business
  • Isolation of rules (as data) from code
  • Requires definition of business terms (data)
  • Code becomes a rules engine
  • Business rules-based methodology (Ross)
  • Close integration of pioneers to Zachmann
  • Emphasis on business data
  • Extends concept of what data is

The 1990s Leading Edge
  • Middleware
  • Alternative to application rewrite
  • Emphasis on data transformation
  • Simplify complicated interfaces by
  • Collecting transformation rules into one place
  • Standardize data interfaces
  • Use of industry standard data interchange
    specification (EDI)
  • Drives need for shared models

The 1990s Leading Edge
  • Web
  • Emphasis on data access and movement
  • Separation of data from presentation and logic
  • HTTP and XML for data transmission and storage
  • Data modeling extended to include storage of
    transitory data (click-stream analysis)
  • Portals for access to information (data in
  • Metadata is important for finding information

The 1990s Leading Edge
  • Metadata
  • Any data used to aid the identification,
    description and location of networked electronic
  • Models of models (of models)
  • Provides context for data
  • Defines data (business terms)
  • Emphasis on business meaning of data
  • Repositories to store metadata

Where are we?
  • Application Development
  • Traditional Mainframe, client-server,
  • O-O, RAD, O-O Patterns and Frameworks
  • Web (HTML, XML, components)
  • Middleware to access legacy data
  • Data Warehouse/Business Intelligence
  • Methodology and Techniques
  • UML and Unified Method
  • Business Rules Methodology
  • Generic Models
  • Zachmann Framework

Where are we in Data Modeling?
  • Relational data modeling
  • Object modeling
  • Dimensional modeling
  • XML modeling
  • Metadata
  • Business rules
  • Generic models (industry subject area) and
  • Data transformation and transmission

Where do we need to be?
  • Cheaper, faster, better
  • Dont start with a blank page
  • Reference models
  • Metadata
  • Consistent view of data across different modeling
    techniques and applications
  • Understanding of relationship of data and
  • Flexible, integrated approach to data

  • Yourdon, Edward, Modern Structured Analysis,
    Yourdon Press, 1989
  • Yourdon, Edward, Just Enough Structured
    Analysis,, 2001
  • Cockburn, Alistair, Software Development as
    Community Poetry Writing, talk given to Central
    Ohio Chapter of the ACM, 1997 from

  • Powell, Ron, A 10 Year Journey, DM Review, Feb.
  • Inmon, Bill, Information Management Charting
    the Course A Brief History of Database Design,
    DM Review, April 2001
  • Appleton, Brad, Patterns and Software Essential
    Concepts and Terminology, http//

  • http//
    (International Affiliation of Library
    Associations and Institutions IFLANET Digital
    Libraries Metadata Resources)

Presenter Information
  • Background
  • Application development
  • Process and data modeling
  • Use of generic industry business models
  • Data transformation
  • Contact Information
  • Phone (614) 249-7284
  • eMail
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