Composition Problems, Causes and Solutions

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Composition Problems, Causes and
Solutions Luyin Zhao J.D.Edwards Program
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Problem Introduction

• Traditionally
• Development is based on single framework
• Frameworks are designed for extension

Bring About

• Framework Composition Problems
• Composition of framework control
• Composition with legacy components
• Framework gap
• Overlap of framework entities
• Composition of entity functionality

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Problem 1Composition of Framework Control
Application Code
Controls invokes
Measurement system framework
GUI framework
Calling Frameworks
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Problem 2 Composition with Legacy Components

• Lack of domain-specific behavior
• Adopt legacy system
• Consequence
• Incompatibility between framework and legacy
  system, such as class name confliction

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Problem 3 Framework Gap

• Two frameworks are non-overlap and the composed
  structure is lack of functionality.
• Consequence
• If the framework is a called framework
• Wrapping Approach
• If the framework is a calling framework
• Complex mediating software is needed

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Problem 4 Composition Overlap of Framework
Entities
It is possible that multiple frameworks contain
the representations of the same real-world
entity. Consequence Composition becomes complex
when different representations influence each
other
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Problem 5 Composition of Entity Functionality
Real world entity involves functionalities from
different frameworks Consequence No simple way
to achieve only by composing respective classes
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Problem 6 Architectural mismatches
Two or more integrated frameworks with different
architectural styles fail to interoperate even
the integration of these systems makes sense from
an application-domain perspective.
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Underlying Causes

• Framework cohesion
• Framework classes have cohesive behavior, which
  is tightly coupled with entities inside
  framework. it is difficult for outside classes to
  gain this behavior

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Underlying Causes

• Domain Coverage
• Lack of domain scope standards. It may cause no
  domain overlap, little domain overlap and
  considerable domain overlap among frameworks.

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Underlying Causes

• Design Intention
• The design for most frameworks is for reuse by
  extension and one-way communication. Several
  issues regarding framework composition were not
  considered in design.

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Underlying Causes

• Access To Source Code
• SE may only get the compiled code or the source
  code is too complex to be analyzed.
• Even wrapper could not solve some problems in
  framework composition

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Solutions for problem 1

• Integrate framework control (change event loops
  in the frameworks).
• Concurrency
• Framework has own control thread
• Wrapping
• Wrapper intercept inter-framework messages
• Remove and rewrite
• Change some control loop (need source code)

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Solutions for problem 2

• Adapter design pattern
• Methods in adapter forward request to the
  equivalent methods in the legacy class
• Change framework
• Change part of framework related with legacy
  class
• Roles
• Represent the frameworks reuse interface as a
  set of roles. Then fill the roles with classes
  related to the framework or existing legacy
  classes

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Solutions for problem 3

• Wrapping
• Extend the missing functionality of a called
  framework through additional API
• Mediating software
• Manage interaction and extend functionalities
  to fill the gap
• Redesign and extend
• Need source code

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Solutions for problem 4

• Multiple inheritance
• take care of updates and conversions between
  different entity representations of two
  frameworks.
• Aggregation
• Contain every entity representations as parts
• Subclassing and aggregation
• Subclass each framework classes representing
  real-world entity, then aggregate them into an
  additional aggregate class
• Subject orientation

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Solutions for problem 5

• Aggregation or multiple inheritance
• Compose the framework classes with the required
  functionality into a single class
• Observer design pattern
• Domain-specific class can be extended with
  notification behavior through Observer design
  pattern

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Solutions for Problem 6

• Modifying or changing architectural components.
• Possible negative impacts, need source code
• Wrapping
• Introducing multilingual framework components.
• Interface adaptation and interface
  standardization