On the horizon

Chapter twenty-five of:

Szyperski, Clemens et al. Component Software - Beyond Object-Oriented

Programming. Second Edition

Contents

Advanced object composition Delegation Split Objects Environmental acquisition Dynamic inheritance

New forms of object and component abstraction Subject-oriented programming Aspect-oriented programming XML Components

Advanced object composition

Class composition is too static for many components applications

Object composition is usually based on message forwarding

The Loss of identity of the whole causes some problems

Delegation

Dependencies between base class and subclass

Delegation-based object composition problem

Performance aspects

Split Objects

A web of objects with a common identity established by means of delegation

Individually a fragment of a split object does not have object status

Delegations across split objects is excluded in this model

Hierarchical split objects Reorganization

Environmental acquisition

Objects are embedded in a containment hierarchy

Delegation or forwarding requests are sent up the containment hierarchy

Dynamic inheritance

The idea is to generalize the concept of a base class to that of a base object selected at object construction time

Rely on delegation between an object and its base object

New forms of object and component abstraction

Fundamental property of objects Traditional inheritance Supertype

Subject-oriented programming

A subject can associate state and behavior with an object identifier as required by that subject

Association of property Separation of concerns along hyperplanes

Aspect-oriented programming

AOP is about explicitly slicing programs according to the various aspects they address

AOP weavers Post-deployment weaving

XML Components

XML world is mostly declarative in nature Still be necessary to establish an appropriate

component concept XML web services

Gamut of markets

Chapter twenty-five of:

Szyperski, Clemens et al. Component Software - Beyond Object-Oriented

Programming. Second Edition

Contents

Component platforms and infrastructure Tools Professional Services

Component platforms and infrastructure

The value of component platforms and infrastructure can exceed that of used components

Approaches to reduce the cost of component construction

Component design and implementation tools

Rests on environmental specifications Should use RAD methods Use the same environment to prototype a

component and implente the component Support for the construction of models and

supporting futher metadata

Component testing tools

Testing of components is the single most demanding aspect of component technology

Systematic aproach to testing are needed Advisable strategies

Component assembly tools

Assembly needs to be automated Differences from hardware assembly

Component system diagnosis and maintenance

Related to component testing Diagnosis is tricky because systems consist

of components from many different vendors Diagnosis tools and ways of operation Requirements of maintenance

Component system and framework architects

These tasks are extremely demanding Independent architecture firms can

concentrate the expertise Few clients X Open markets

Component assembly consultants

Component assembly is supposedly simple… Component specializing in assembly of

components can find a broad market COTS (commercial off the shelf) Act knowing well the potential and

limitations of products and helping gauge the risks and benefits

Component configuration management

Outsourcing Monitoring of component markets Development of gradual migration plans and

the integration Migration from monolithic solutions to

component-based ones

Component warehouses, marketing, and consulting

Traditional aspects… All activities are likely to be fully electronic Legal and practical protection offered by

physical package becomes unnecessary

Component operators, web services, application service

providers

Component paired with a service provider forms a marketplace service

Business model will be concentrated in provisioning service combined with availability and help desk services

Any question?