Software Development and Configuration Management

Chapter 5 - Implementation

• Chapter 5 covers implementation in software development.
• The presenter is Dr. Noorayisahbe Binti Mohd Yaacoub.
• The topics covered include understanding implementation, its concept, issues, and open-source development.

Topics Covered

• What is implementation?
• Implementation Concept
• Implementation Issues
• Open Source Development

Design and Implementation

• Software design and implementation is a stage in software engineering where an executable system is developed.
• Design and implementation activities are interconnected.
• Software design involves identifying software components and their relationships based on customer requirements.
• Implementation involves realizing the design as a program.

Build or Buy

• In many domains, off-the-shelf systems (COTS) can be adapted to user needs.
• Purchasing pre-built systems for medical records, for example, can be faster and cheaper than starting from scratch.
• Using configuration features of purchased systems is part of the design process when implementing these systems.

SDLC Phases

• The software development life cycle (SDLC) includes stages like Requirements, Analysis, Design, Implementation, and Testing.
• Implementation is a crucial step in this cycle.

Implementation Concept

• Each class is implemented according to the design document.
• Each class is tested to ensure expected behavior (correct output for correct input, meeting timing requirements).
• Classes are integrated to produce the final system.

Implementation Issues

• Focuses beyond programming:
  • Reuse: Reusing existing components or systems in software development is common practice.
  • Configuration management: Keeping track of different versions of software components throughout development.
  • Host-target development: Software is often developed on one machine (host) but executed on another (target).

Reuse

• From the 1960s to the 1990s, new software was typically developed from scratch.
• Reuse of functions and objects in libraries was limited.
• Costs and time constraints made a reusable approach increasingly essential.
• Reusing existing software is now central in business and science.

Reuse Levels

• Abstraction level: Reusing knowledge of successful design patterns.
• Object level: Reusing objects from libraries.
• Component level: Reusing collections of objects/object classes in application systems.
• System level: Reusing complete application systems (e.g., COTS).

Software Reuse

• Diagram showing different levels of software reuse (abstraction, object, component, system).
• Systems (COTS)
• Components
• Object
• Programming language libraries
• Abstraction (architectural and design patterns)

Reuse Costs

• Cost of searching/evaluating reusable software.
• Cost of purchasing reusable software (higher for large systems).
• Adapting/configuring reusable components/systems to project requirements.
• Integrating reusable elements with each other and newly developed code.

Configuration Management

• The process of managing evolving software systems, particularly when development is collaborative.
• The goal is to support the integration process (access to code/documents, tracking changes, component compilation/linking) through a system.
• Crucial for managing multiple versions and developer contributions.

Configuration Management Activities

• Version management: Tracking different versions/configurations of components.
• Coordinating development by multiple programmers through version control/management systems.
• System integration: Defining versions/configurations for complete systems and automatically building these systems from component versions.
• Problem tracking: Reporting bugs, identifying who to contact, tracking fixes.

Configuration Management Tool Interaction

• Diagram showing interaction between various components (e.g., change proposals, change management, system versions, release management).

Host-Target Development

• Most software development is host-target.
• Development platform (host) for design/creation, and target platform (e.g. different machine) for execution.
• The software development platform includes operating systems, supporting software (e.g., databases), IDEs, compilers, and testing tools.

Development Platform Tools

• Integrated compiler and syntax-directed editors for code creation/editing/compilation.
• Code debugging support.
• Tools for diagramming (e.g., UMLs).
• Testing tools (e.g., JUnit).
• Tools for managing various projects.

Integrated Development Environments (IDEs)

• IDEs (Integrated Development Environments) group several development tools into a common system.
• They often provide a common framework or user interface supporting multiple facets of software development.
• IDEs can be designed for a specific language (e.g., Java) or have specific language support within a more generic IDE.

Component/System Deployment Factors

• Components need platforms with required hardware/software support.
• High-availability systems often need components on multiple platforms.
• Communications traffic between components favors deploying these components on the same or similar platforms.

Open Source Development

• Approach using published source code; volunteers contribute.
• Rooted in the Free Software Foundation concept.
• Source code is typically not proprietary but available for examination/modification.
• Open source software facilitates wider community involvement through internet-based recruitment of developers/users.

Open Source Systems

• Linux is a well-known open source operating system used broadly as a desktop/server OS.
• Java, Apache web server, and MySQL are other noteworthy open-source products.

Open Source Issues

• Should the development being done use open source components?
• Should an open-source approach be used for the system?

Open Source Business

• Companies increasingly use an open-source approach.
• Business models are now often based on selling support, not just the software itself.
• These companies believe community involvement leads to quicker, cheaper development and greater user participation.

Open Source Licensing

• Open-source requires freely available source code.
• Developers own the code and control (legally) how it's reused.
• Developers can include restrictions in legally binding licenses.
• Open source components can potentially imply open-source implementation for an entire new system; others might just allow use without further imposition. (Evolve from the system they are initially used in.)

License Models

• GPL (General Public License): Reciprocal license–code must be open-source if licensed under the GPL.
• LGPL (Lesser General Public License): Developer might not have to release source code for components linked to open source code.
• BSD (Berkeley Software Distribution) License): Non-reciprocal license (developers aren't obliged to re-open source code for any changes made.)

License Management

• Keep an information system for tracking/managing open-source components.
• Understand different types of licenses.
• Be aware of component evolution.
• Educate people regarding open-source.
• Implement auditing systems.
• Participate in open-source community.

Key Points

• Software design and implementation are interlinked.
• Detail in design depends on whether plan-driven or agile approach used.
• Reusing existing software (components, services, full systems) is often wise.
• Configuration management (essential for collaborative development) is necessary when making adjustments to a system.
• Host-target development (using IDE on a host machine, transferring software to a target execution machine) is the usual setup for software production.
• Open-source development (making source code public) allows broader participation from the community for suggestion/improvement.