Trends in Adaptive Object Model Research
Filipe Figueiredo Correia1,2 and Hugo Sereno Ferreira1,3
1
ParadigmaXis — Arquitectura e Engenharia de Software, S.A.,
Avenida da Boavista, 1043, 4100-129 Porto, Portugal
{filipe.correia,hugo.ferreira}@paradigmaxis.pt
http://www.paradigmaxis.pt/
2
FEUP — Faculdade de Engenharia da Universidade do Porto,
Rua Dr. Roberto Frias, s/n 4200-465, Porto, Portugal
filipe.correia@fe.up.pt
http://www.fe.up.pt/
3
MAP-I Doctoral Programme in Computer Science
hugo.ferreira@di.uminho.pt
http://www.map.edu.pt/i

Contents

Model Driven Engineering

Adaptive Object Models (AOMs)

The Design of AOMs

The Oghma System

Open Issues

Future Work in Oghma

Final Remarks
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 2

Model Driven Engineering

Abstracting business domains and technology

Requirements

Design and implementation

Different approaches to modeling

Static – centred on documentation, or generative techniques

Dynamic – runtime models
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 3

Adaptive Object Models

Dynamic meta­modeling technique

Several abstraction levels in play at runtime

A meta­model is seen as a first­class model

MOF could be used to handle the different levels
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 4

Adaptive Object Models
Many object­oriented information systems share an architectural style that
emphasizes flexibility and run­time adaptability. Business rules are stored
externally to the program such as in a database or XML files instead of in
code. The object model that the user cares about is part of the database, and
the object model of the code is just an interpreter of the users' object model.
We call these systems \"Adaptive Object­Models\", because the users' object
model is interpreted at runtime and can be changed with immediate (but
controlled) effects on the system interpreting it.
Joseph Yoder, et al. [11]
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 5

The Design of AOMs – Common Design
See references [4], [5] and [8].
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 6

The Design of AOMs – Design Patterns

Core 
GUI
TypeSquare; TypeObject; Property; PropertyRenderer; EntentyView; DynamicView;
Accountability; ValueObject; NullObject; Workflow
SmartVariable

Process

Creational
DomainSpecificAbstraction; SimpleSystem;
Builder; AOMBuilder; DynamicFactory; ThreeExamples; WhiteBox, BlackBox;
Bootstraping; DependencyInjection; ComponentLibrary; Hotspots; PluggableObjects;
VisualLanguage Fined­GrainedObjects; VisualBuilder;
LanguageTools

Behavioral 
Instrumental
DynamicHooks; Strategy; RuleObject;
RuleEngine; Typecube; Interpreter ContextObject; Versioning; History; Caching
Welicki et al. [14]
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 7

The Oghma System

Based on an AOM

Heads towards a framework for information systems

Is an adaptive system at several levels

Model

Messages

Addressing

User interface

Persistence
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 8

The Oghma System – OO Meta-Model Design
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 9

The Oghma System – What does it bring of new?
Has Oghma's approach something of new to add to
AOM's already known and documented issues?
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 10

The Oghma System – Research fronts

Persistence

Modeling Language

Business Rules

Client­Server architecture

Queries

Addressing scheme

User Interfaces
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 11

The Oghma System – Persistence

Based on model transformation techniques

Bijective transformations between relational and
object models (only at the instance level)
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 12

The Oghma System – Modeling Language

UML­based, but does not cover all of UML's
specification

Supports Interfaces, Associative Classes and
Navigability

Finding the right level of expressiveness
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 13

The Oghma System – Modeling Language Example
<?xml version=\"1.0\" encoding=\"UTF-8\"?>
<model><data>
(...)
<entity id=\"computer\" name=\"Computer\" tostring=\"{brand} {model} (€{price})\">
<list format=\"{brand} {model} | {price}\" columns=\"{brand} {model} | {price}\" />
<attr id=\"brand\" name=\"Brand\" domain=\"string\" cardinality=\"1\" />
<attr id=\"model\" name=\"Model\" domain=\"string\" cardinality=\"1\" />
<attr id=\"price\" name=\"Price\" domain=\"integer\" cardinality=\"1\" />
<attr id=\"yearbought\" name=\"yearbought\" domain=\"integer\" cardinality=\"1\" />
</entity>
<entity id=\"desktop\" name=\"Desktop\" inherits=\"Computer\"/>
<entity id=\"laptop\" name=\"Laptop\" inherits=\"Computer\">
<attr id=\"weight\" name=\"Weight\" domain=\"integer\" cardinality=\"1\" />
</entity>
<entity id=\"part\" name=\"Computer part\">
<attr id=\"name\" name=\"Name\" domain=\"string\" cardinality=\"1\" />
<attr id=\"type\" name=\"type\" domain=\"enum\" cardinality=\"1\" />
</entity>
<relationship id=\"rel_computer_part\">
<node entity=\"computer\" id=\"parts\" name=\"Detalhes\" cardinality=\"0..*\" navigable=\"true\" />
<node entity=\"part\" id=\"computers\" name=\"Dimensões\" cardinality=\"0..*\" navigable=\"false\" />
</relationship>
(...)
</data></model>
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 14

The Oghma System – Business Rules

Defined in a declarative way, and part of the model

Enforced on the server side (semantic integrity)

Enforced on the client side (inputs validation; rapid feedback)
Example
<?xml version=\"1.0\" encoding=\"UTF-8\"?>
(...)
<entity id=\"book\" name=\"Book\" inherits=\"Document\">
<attr id=\"title\" name=\"Title\" domain=\"string\" />
<attr id=\"isbn\" name=\"ISBN\" domain=\"string\"
regex=\"^[0-9]{3}-[0-9]-[0-9]{2}-[0-9]{6}-[0-9]$\" />
<attr id=\"author\" name=\"Author\" domain=\"string\" cardinality=\"1..*\" />
</entity>
(...)
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 15

The Oghma System – Client-Server

Adaptive model­based message schema

Exchange of meta­level and operational­level
elements

REST/XML over HTTP (eased debugging, caching, authentication)
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 16

The Oghma System – Queries

Two querying meta­models

Object­oriented (serializable/deserializable to a URL­based representation)

Relational­oriented (serializable to SQL)

Object­oriented query instances are transformed into
relational­oriented query instances
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 17

The Oghma System – Addressing Scheme

Directly derives from the use of RESTfull resources

Adaptive model­based addressing
Example
http://oghma.paradigmaxis.pt/computer/laptop/@schema
http://oghma.paradigmaxis.pt/computer/laptop/4A3615F1-5A91-22E4-0B1D-1416F93D4412
http://oghma.paradigmaxis.pt/computer/laptop/4A3615F1-5A91-22E4-0B1D-1416F93D4412/parts
http://oghma.paradigmaxis.pt/computer/laptop[yearbought lt 2005]
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 18

The Oghma System – User Interfaces

Adaptive model­based user interfaces

Rendering of entities

Rendering of value properties (attributes)

Rendering of instance properties (relations)

Renderers chosen according to model information

Attribute types

Cardinalities

Navigability
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 19

The Oghma System – User Interfaces Example (1)
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 20

The Oghma System – User Interfaces Example (2)
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 21

Open Issues in AOMs

Higher initial development cost

Higher complexity than traditional systems

Harder to understand and maintain

Model maintenance

Development of tools from scratch

Model evolution

Need to assess the impact of AOMs on software
quality metrics
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 22

Future Work in Oghma (1)

Meta­model transformations

Monolithic vs rule­based

Model evolution

Mapping elements from two different meta­models

Leverage the concept of refactorings (meta­refactorings?)

Develop tools that assist the migration process
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 23

Future Work in Oghma (2)

Ontology model

A form of knowledge representation

A possible replacement for the UML­oriented meta­model

Formalize this new knowledge as design patterns
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 24

Final Remarks

Use when domain models change at a fast rate

Oghma was developed with little knowledge of the
existing research on AOMs

It has now taken some benefit from this knowledge

It possesses also some characteristics that haven't
been documented before in the context of AOMs
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 25

The End
or perhaps just the beginning...
Filipe Figueiredo Correia & Hugo Sereno Ferreira Trends In Adaptive Object Models Research 26
http://flickr.com/photos/21443321@N06/2103626456/

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