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Software process. Topics covered. Review the previous lecture Software Process RUP- Rational Unified Process. Review. Abstract representation of a process Framework of a process and hide the details of a specific activity Software process models Waterfall model
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Topics covered • Review the previous lecture • Software Process • RUP- Rational Unified Process
Review • Abstract representation of a process • Framework of a process and hide the details of a specific activity • Software process models • Waterfall model • Evolutionary development • Exploratory development • Thro-away prototyping • Component-based engineering • Based on COTS • Process iteration • Incremental delivery • Spiral development
Process activities • There are four basic process activities: • Software specification • Software design and implementation • Software validation • Software evolution
Software specification or requirement Engineering • The process of establishing what services are required and the constraints on the system’s operation and development. • This process leads to the production of a requirements document( specification of the system). • Requirements engineering process • Feasibility study; • Requirements elicitation and analysis; • Requirements specification; • Requirements validation.
Feasibility study • is not used to solve the problem but is use to determine weather • the proposed system will be cost effect • if it can be developed with the existing budgetary • The result from this study is to inform the decision of whether or not to go ahead within the constrain • The report should be cheep and quick
Requirements elicitation and analysis • Discover the requirements from • Existing system • Discussion with user • Task analysis • You may use • System relative model • Prototypes
Requirements specification • In this process is about translating information gathered during the system analysis into into two documents • user or customer document includes abstract statements of the system requirements • Software developer documents includes more detailed description of the functionality to be provided.
Requirements validation • In this process, you are going to check if the requirements are • Real • Consistent • Complete All these process is going to continue during definition and specification.
Software design and implementation • The process of converting the system specification into an executable system. • Software design • Description of the structure of the software to be implemented, the data which is part of the system, interface between system component, and algorithm that realises the specification; • For example: library system • the design will be through of a number of versions. For each time you are going to add details and constrains with backtracking to correct the error in the earlier design. • The design process may involve developing several models of the system at different levels of abstraction.
Software design and implementation • Implementation • Translate this structure into an executable program; • The activities of design and implementation are closely related and may be interleaved.
Design process activities • Input to design process • The software interface with other software system • OS, DB, other application program • For example: weather system ( real time system)- input comes from outside DB and application program to feed weather system to retrieve suitable and correct output display • Requirement specification is a description of the functionality the software that must provide
Design process activities • Design activities • Architectural design • Identify the overall structure includes • Sub-system if you used incremental development • Their relationship • How they are distributed • Interface design • Interfaces between components if you use sub-system. The interface specification should must unambiguous to implement them correctly. • Component design • Take each component and design how it will operate; simple statement of expected functionality to be implemented • Data structure design • design database structure and how these are to be presented • It can be existing database or create a new database
Design process activities • Output from design process • Set of design outputs • In OO approach, the output mostly be diagrams and in may cases automatically generate code • In agile method, the output may be represented in the code of program. • Possible models • Object model; • Sequence model; • State transition model; • Structural model; • Data-flow model.
Programming and debugging • Programming is translating a design into a program • There in no general programing process that is usually followed • You may use software development tools (CASE TOOLS) to generate a skeleton program from a design. • You may start from well understood components then move less-understood components or versa vice. • Code the interfaces between these components • debugging is removing errors from that program. • Programmers carry out some program testing to discover faults in the program and remove these faults in the debugging process.
Programming and debugging • Defect testing and debugging are different processes. • Testing establishes the existence of defects. • Debugging is concerned with locating and correcting these defects. • Testing may involve tracing the program code manually required new test cases to localize the problem; Or • You may use debugging tools to trace the code and find where are the errors.
Software validation • Verification and validation (V & V) is intended to show that a system conforms to its specification and meets the requirements of the system customer. • It is check list processing at each stage of the software process • System testing involves executing the system with test cases that are derived from the specification of the real data to be processed by the system.
Testing stages • Component or unit testing • Individual components are tested independently; • Components may be functions or objects or coherent groupings of these entities. • System testing • Testing of the system as a whole. Testing of emergent properties is particularly important. • Acceptance testing • Testing with customer data to check that the system meets the customer’s needs.
If an incremental approach to development is used, each increment should be tested as it is developed, • Alpha vs. beta test • Acceptance testing is sometimes called alpha testing. Custom systems are developed for a single client. • When a system is to be marketed as a software product, a testing process called beta testing • Beta testing involves delivering a system to a number of potential customers who agree to use that system
Software evolution • Software is inherently flexible and can change. • As requirements change through changing business circumstances, the software that supports the business must also evolve and change. • Although there has been a demarcation(limit) between development and evolution (maintenance), this is increasingly irrelevant as fewer and fewer systems are completely new.
The Rational Unified Process • A modern process model derived from the work on the UML -an object oriented modeling language - and associated process. • Takes the advantages of three generic processes • Good practice in specification and requirements • Support prototyping and incremental delivery • Normally described from 3 perspectives • A dynamic perspective that shows phases over time; • A static perspective that shows process activities; • A practice perspective that suggests good practice of software development.
RUP phases • Identify four discrete phases in software processes ( related to business point of view ) • Phases are • Inception • Establish the business case for the system. • You should identify all external entities (people and systems) that will interact with the system and define these interactions. • Elaboration • Develop an understanding of the problem domain and the system. • establish an architectural framework for the system, develop the project plan and identify key project risks Design use case, an architectural description and development design.
RUP phases • Construction • System design, programming and testing. • Developed in parallel an integrated • system sequence, state machine, and class diagram are design • software system and their documentation to be ready to deliver to the user. • Transition • Deploy the system in its operating environment. • move the system from software development community to user community • you should have a documented software system that is working correctly in its operational environment.
2- Static view • RUP focuses on the activities that take place during the development process • It is called workflows in the RUP description. • There are six core process workflows identified in the process and three core supporting workflows.
3- RUP good practice • Develop software iteratively based on customer priority • Manage requirements by keep tracking of user changes to their requirements. • Use component-based architectures; system architecture based on component • Visually model software; use graphical UML models to present static and dynamic views of the software.
RUP good practice • Verify software quality;Ensure that the software meets the organizational quality standards. • Control changes to software; Manage changes to the software using a change management system and configuration management procedures and tools
Key points • Software processes are the activities involved in producing and evolving a software system. • Software process models are abstract representations of these processes. • General activities are specification, design and implementation, validation and evolution. • Generic process models describe the organisation of software processes. Examples include the waterfall model, evolutionary development and component-based software engineering. • Iterative process models describe the software process as a cycle of activities.
Key points • Requirements engineering is the process of developing a software specification. • Design and implementation processes transform the specification to an executable program. • Validation involves checking that the system meets to its specification and user needs. • Evolution is concerned with modifying the system after it is in use. • The Rational Unified Process is a generic process model that separates activities from phases. • CASE technology supports software process activities.