Adaptive Object-Models Joseph W. Yoder University of Illinois The Refactory, Inc.

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Metadata and Adaptive Object-Models "Anything you can do, I can do Meta" Metadata: If something is going to vary in a predictable way, store the description of the variation in a database so that it is easy to change….Ralph Johnson ”Meta is Beta"

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Metadata can be described by saying that if something is going to vary in a predictable way, store the description of the variation in a database so that it is easy to change. In other words, if something is going to change a lot, make it easy to change. The problem is that it can be hard to figure out what changes, and even if you know what changes then it can be hard to figure out how to describe the change in your database. Code is powerful, and it can be hard to make your data as powerful as your code without making it as complicated as your code. But when you are able to figure out how to do it right, metadata can be incredibly powerful, and can decrease your maintenance burden by an order of magnitude, or two. [R. Johnson] What is meant by Metadata ?

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. General Problem zRequirements change within applications’ domain. zBusiness Rules are changing rapidly. zApplications have to quickly adapt to new business requirements. zChanging the application is costly, it generally includes code and data-storage. zThere are cycles of: build-compile-release.

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. General Solution zCreate an object design (meta-model) that describes the domain objects which includes attributes, relationships, and business rules as instances rather than classes. zThe domain objects are instantiated through a description given by the user or domain expert. zEach new requirement is satisfied by creating a new description and a new instantiation.

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Adaptive Object-Model (Dynamic Object-Model) yAn ADAPTIVE OBJECT-MODEL is an object model that provides “meta” information about the domain so that it can be changed at runtime xexplicit object model that it interprets at run-time xchange the object model, system changes its behavior yADAPTIVE OBJECT-MODELS usually arise as domain-specific frameworks yBusiness rules can be stored in ADAPTIVE OBJECT- MODELS

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Architectural Elements of AOM Metadata TypeObject Properties Type Square Entity-Relationship Strategy/RuleObjects Interpreters/Builders Editors/GUIs

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Adaptive Object-Model (Dynamic Object-Model) zType-Object zProperties zStrategy / Interpreter zSchema / Descriptor zSmart Variables zBuilders / Editors Brian Foote:

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Adaptive Object-Model zWhen to Build AOMs yNeed for flexibility yHigh pace of business change yNeed for experimentation yNeed to empower user

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Type-Object PLoPD3 - Johnson and Woolf

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Properties PLoP98 - Foote and Yoder

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Strategies Design Patterns - GOF95

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Adaptive Object-Model (Very Common Structure) Type Square ECOOP & OOPSLA 2001 Yoder, Balaguer, Johnson

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Interpreters / Builders: Solution

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Medical Observations

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Observation Example

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Metamodel and GUI zThe metadata can simplify building user interfaces. Special GUI components can be developed for using the metadata. zExample: The Observation model includes widgets that display list of values from the DiscreteValidators and also EntryBoxes that use RangeValidator. zA Mediator and Adaptor layer was developed for managing the interactions between the domain objects and the GUIs.

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. PartyType: Metadata-Editors

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Accountability: Metadata-Editors

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Observation: Metadata-Editors

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Observation: Metadata-Editors

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Observation: Metadata-Editors

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Copyright by ECOOP’ 2000 workshop on Adaptive Object-Model An execution of that software A language for defining domain specific software A specific software language for defining languages Dimensions of abstraction in Adaptive Object-Models, Reflection and OMG ’s metamodeling Architecture L3 L2 L1 L0 MOF

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Advantages of AOM zSystems can more easily be adapted to domain changes. zChanges do not require recompiling the system. zPower Users can change the business rules. zShorter time-to-market. zSmaller in terms of classes so can be easier to maintain by experts.

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Disadvantages of AOM zDeveloping AOM is expensive. (higher startup costs) zCan be hard to understand and maintain. (user-model and meta-model) zIt requires skilled human resources. zCan have poor performance. zIt demands having infrastructure for storing, building, interpreting metadata (special support tools, editors, etc).

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Other Approaches and Technologies zBlack-box Frameworks zCode Generators zMetamodeling Techniques zTable-driven Systems zGenerative Techniques

Adaptive Object-Models – Joe Yoder Workshop Session, ECOOP’2001 – June 2001, Budapest, Hungary. Copyright 2001, The Refactory, Inc. Where to Find More Information zhttp:// zhttp://st- zhttp:// zhttp://hillside.net zhttp://st- zhttp:// zhttp://