CBSE process: Issues and challenges

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CBSE process Issues and challenges

• Presented by
• Asha Chitrapur

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Topic Overview

• The challenges of SW- how can CBD help?
• What is a software component?
• Component-based Software Engineering
• Case study
• Problems and research issues
• Conclusion
• References

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The challenges of software engineering - how can
component software help?

• Software engineering problems
• The software crisis (1968) still exists
• SW is late
• SW is buggy
• SW is expensive
• How to develop high quality software in an
  efficient an inexpensive way?

NATO conf 1968 SW crisis SW engineering components
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SW problems and CBD

• SW is late ,buggy ,expensive
• because too often applications are
  created instead of constructed, requiring
• re-invention
• re-coding
• re-testing
• Component-based software engineering
  focuses on reuse of
• subsystems
• infrastructure

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Component Definitions

• Councill and Heinmann
• A software component is a software element that
  conforms to a component model and can be
  independently deployed and composed without
  modification according to a composition standard.
• Szyperski
• A software component is a unit of composition
  with contractually specified interfaces and
  explicit context dependencies only. A software
  component can be deployed independently and is
  subject to composition by third-parties.

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Component-Based Software Engineering

• Component-based software engineering (CBSE) is an
  approach to software development that relies on
  software reuse
• Developing new software from pre-built
  components.
• Attempt to make an association between SE and
  other engineering disciplines.

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• This approach is based on the idea to develop
  software systems by selecting appropriate
  off-the-shelf components and then assemble them
  with a well-defined software architecture.
• CBSE has three major functions
• Developing software from prefabricated,reusable
  parts.
• The ability to use those parts in other
  applications.
• Easily maintaining and customizing those parts to
  produce new functions and features.

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Component-based software construction (1)
components
Component
1
construction
application
Component
Component
Component
1
2
4
Component
2
Component
Component
3
4
Component
3
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Component-based software construction (2)
Application 1
Component
Component
1
2
Component
Component
components
3
4
Component
construction
Application 2
1
Component
Component
1
5
Component
Component
3
6
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Component-based software construction (3)
application
Component
Component
component
1
2
New Component 4
Component
Component
3
4
update
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CBSE Process model

• Gather requirement
• Establish architectural design
• Examine requirements to determine what subsets
  are amenable to composition
• Identify components required
• Hunt for component (in-house or COTS)

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Component Identification Issues

• Trust
• You need to be able to trust the supplier of a
  component
• At best, an untrusted component may not operate
  as advertised at worst, it can breach your
  security
• Requirements
• Different groups of components will satisfy
  different requirements
• Validation
• The component specification may not be detailed
  enough to allow comprehensive tests to be
  developed
• Components may have unwanted functionality how
  can you test this will not interfere with your
  application?

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Ariane Launcher Failure

• In 1996, the first test flight of the Ariane 5
  rocket ended in disaster when the launcher went
  out of control 37 seconds after take off
• The problem was due to a reused component from a
  previous version of the launcher (the Inertial
  Navigation System) that failed because
  assumptions made when that component was
  developed did not hold for Ariane 5
• The functionality that failed in this component
  was not required in Ariane 5

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Differences from other processes

• Team attempts to modify or remove system
  requirements that cannot be implemented with COTS
  or in-house components
• If requirement cannot be changed or deleted, then
  target component development (CBD)

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Lifecycle of a Component based System
Requirements Analysis
Software Architecture Analysis Selection and
Evaluation
Component identification and customization
System Integration
System Testing
System Maintenance
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Case Study

• Software Engineering Laboratory (SEL), known for
  empirical study of software development practice,
  provides guides to NASA/GSFC projects.
• SEL developed a process for COTS-based
  development for Flight Dynamics Division
• 15 COTS projects were studied to evaluate and
  improve the process model

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Case study Objectives

• To learn about the actual COTS process used at
  the FDD at NASA
• To analyze the issues raised by the project
  members
• To define a new process to address and resolve
  these issues

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Development process
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3 Types of COTS-based Systems

• Defined by Carney
• Turnkey systems Build around a suite of
  commercial products such as Microsoft Office.
  Customization does not change the nature of the
  initial product.
• Intermediate systems Built around one COTS but
  integrate other (also developed in-house)
• Other Built on several COTS with same importance.

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Study of the Actual Process

• Structured interviews using the GQM approach
• 25 representatives from 15 projects in 2. and
  3.category of Carney definition.
• Two study teams
• Interviewer
• Scribe
• Analysis by constant comparison method

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Major issues

• Slippage in schedule due to delays in releasing
  COTS by vendor
• Incomplete or non-reliable documentation
• The learning curve with the product is hard to
  estimate
• Not all promised functions are implemented
• Communication with vendor can be one way

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Differences between COTS projects and traditional
projects

• More effort on requirements, test and
  integration, less on design and coding.
• 3 types of differences
• New activities COTS selection, COTS
  familiarization, vendor interaction
• Reduced activities coding, debugging, unit
  testing.
• Modified activities design, architecture issues
  (compatibility, configurability)

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Disadvantage of COTS projects

• Dependence on vendor functionality available,
  the schedule for release, the reliability level,
  documentation
• Flexibility in requirements COTS drives the
  requirements at least to some extent
• A trade-off between disadvantage and the benefits
  of COTS

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New COTS Process

• Main phases are
• Requirement
• Design
• Coding
• Integration

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Requirements

• Make versus buy decision I
• Consider trade-off between non-technical issues
  and disadvantages of COTS project
• Requirement definition
• COTS identification and selection
• Graph based modeling of the component
  acquisition problem.
• COTS familiarization learn about COTS

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Requirements contd

• Feasibility study
• describe the product on a high level, an effort
  estimation, a risk assessment model. Both for
  COTS and non-COTS.
• Make versus buy decision II
• The result is the product variant that will be
  developed
• Requirements Review

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Design

• Definition of architecture and integration issues
  at lower level of details
• Decision on glueware
• Design Review

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New Roles

• COTS Team
• At the organization level
• A repository about COTS
• Interface with vendors
• At the project level
• Build partnership with vendors

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Conclusion

• COTS-based processes differ considerably from
  traditional software development
• New activities
• Reduced activities
• Modified activities
• Disadvantage of COTS projects
• Dependence on vendors
• Flxibility in requirements

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Conclusion

• CBSE can help overcome the challenges faced by
  traditional software development mechanisms,
  nevertheless its adoption requires, as any new
  practice, utmost care by software development
  organizations.

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Thank you for your attention!

• References
• 1 Council, William T. and Heineman, George T.,
  Component-Based Software Engineering.
  Addison-Wesley Upper Saddle River, 2001.
• 2 Pour, Gilda, Component-Based Software
  Development approach New Oppurtunities and
  Challenges, Proceedings of the 26th
  International Conference on Technology of
  Object-Oriented Languages and Systems, 1998.
• 3 Crnkovic, Ivica, Component-based Software
  Engineering New Challenges in Software
  Development, in 27th Int. Conf. Information
  Technology Interfaces ItI 2003, June 1-19, 2003,
  Cavtat, Croatia.
• 4 Way, Ju An, Towards Component-Based Software
  Engineering, Proceedings of the eighth annual
  consortium on Computing in Small Colleges Rocky
  Mountain conference, pg. 177-189, Orem, Utah,
  2000