Coursehero >> Nevada >> Nevada >> CSE 425

Course Hero has millions of student submitted documents similar to the one below including study guides, homework solutions, papers, exam answer keys and textbook solutions.

q CS425/CS625 q q q List of classes for the banking system Groups for projects Software development process Assignment 1 Due Sept 11, 2001 Individual AND group portions Requirements for Galaxy Sleuth Questions (group) Informal scenarios group and individual Computer Science Software Engineering Slide 1 Groups Paul Simmerlink Stephen Herbert Daniel Coming Ogechi Ugwulebo James King Maggie Lu Reid Webber Taisuke Nagayama Jeff Payne Matasaka Sako Jigna J. Bhatt Brett Harrison Jonathan Ward Michael Vidal Howard C. Wu Casey J. Powell Shana Rheault RichardD.VanHorn Rodel Mangoba Steve Luong Don Miller James Frye David Brewer Olja Mihic Casey Mees Jason Dodd Beifang Yi Dorothy P. Cheung William Nelson Will Woolsey Andrew Rodgers James Cohen, Judy Rowley, Stan Sexton, Rajashekhar Yakkali, Kazuhito Mori Computer Science Software Engineering Slide 2 Engineering and Administration Computer Science Software Engineering Slide 3 Informal Scenarios q q q Help understand the problem Come up with questions on requirements Help constrain architecture Computer Science Software Engineering Slide 4 Informal Scenarios - Guidelines q q q q q q Large number of small informal scenarios short scenarios An informal scenario should address one coherent aspect of the system (logon, make a move, ) Should specify concrete values Address some errors Implementation details must not be in informal scenario Each informal scenario should have the form: System state at start Informal scenario Next informal scenario in sequence Computer Science Software Engineering Slide 5 Sample: User makes a move q q q Current system state: The system state consists of each player at his or her starting location on the game board. The 3 players in the game, Andrea, Max, and Emma have each been dealt six cards (evidence). Value of cards is irrelevant to this scenario Informal Scenario: Andrea has the next move. She spins the spinner which lands on the number 5. Andrea has the white playing piece. She moves this piece one space to the left, one space toward the top, two spaces to the right, and finally, one space to the top. Because of the final position of the game piece, Andrea has not additional option and her turn ends. Next scenario: The player to the left of Andrea goes next, Max goes next Software Engineering Slide 6 Computer Science Software Processes q Coherent sets of activities for specifying, designing, implementing and testing software systems Computer Science Software Engineering Slide 7 Objectives q q q To introduce software process models To describe a number of different process models and when they may be used To describe process models for requirements engineering, software development, testing and evolution Computer Science Software Engineering Slide 8 Topics covered q q q q q q q Software process models Process iteration Software specification Software design and implementation Software validation Software evolution Automated process support Computer Science Software Engineering Slide 9 The software process q A structured set of activities required to develop a software system Specification Design Validation Evolution q A software process model is an abstract representation of a process. It presents a description of a process from some particular perspective Software Engineering Slide 10 Computer Science Generic software process models q The waterfall model Separate and distinct phases of specification and development q Evolutionary development Specification and development are interleaved q Formal systems development A mathematical system model is formally transformed to an implementation q Reuse-based development The system is assembled from existing components Computer Science Software Engineering Slide 11 Waterfall model Requirements definition System and software design Implementation and unit testing Integration and system testing Operation and maintenance Computer Science Software Engineering Slide 12 Waterfall model phases q q q q q q Requirements analysis and definition System and software design Implementation and unit testing Integration and system testing Operation and maintenance The drawback of the waterfall model is the difficulty of accommodating change after the process is underway Computer Science Software Engineering Slide 13 Waterfall model problems q q q Inflexible partitioning of the project into distinct stages This makes it difficult to respond to changing customer requirements Therefore, this model is only appropriate when the requirements are well-understood Computer Science Software Engineering Slide 14 Evolutionary development q Exploratory development Objective is to work with customers and to evolve a final system from an initial outline specification. Should start with well-understood requirements q Throw-away prototyping Objective is to understand the system requirements. Should start with poorly understood requirements Computer Science Software Engineering Slide 15 Evolutionary development Concurr ent activities Initial version Specification Outline description Development Intermediate versions Validation Final version Computer Science Software Engineering Slide 16 Evolutionary development q Problems Lack of process visibility Systems are often poorly structured Special skills (e.g. in languages for rapid prototyping) may be required q Applicability For small or medium-size interactive systems For parts of large systems (e.g. the user interface) For short-lifetime systems Computer Science Software Engineering Slide 17 Formal systems development q q q Based on the transformation of a mathematical specification through different representations to an executable program Transformations are correctness-preserving so it is straightforward to show that the program conforms to its specification Embodied in the Cleanroom approach to software development Computer Science Software Engineering Slide 18 Formal systems development R ue et e i m s qr n dfni n e io i t Fr a om l s eii a o pc ct n f i Fr a om l ta somi n rnf r a o t I t g to ad n r inn ea s se t si g yt m tn e Computer Science Software Engineering Slide 19 Formal transformations Formal transformations T1 T2 T3 T4 Formal specification R1 R2 R3 Executable program P1 P2 P3 P4 Proofs of transformation correctness Computer Science Software Engineering Slide 20 Formal systems development q Problems Need for specialised skills and training to apply the technique Difficult to formally specify some aspects of the system such as the user interface q Applicability Critical systems especially those where a safety or security case must be made before the system is put into operation Computer Science Software Engineering Slide 21 Reuse-oriented development q q Based on systematic reuse where systems are integrated from existing components or COTS (Commercial-off-the-shelf) systems Process stages Component analysis Requirements modification System design with reuse Development and integration q This approach is becoming more important but still limited experience with it Computer Science Software Engineering Slide 22 Reuse-oriented development R uirem eq ents sp ecificatio n C p en om on t an sis aly R uirem eq ents m if od icatio n Ss y temd ign es w r e ith eus D elo m t ev p en an in ration d teg S tem ys va lidatio n Computer Science Software Engineering Slide 23 Process iteration q q q System requirements ALWAYS evolve in the course of a project so process iteration where earlier stages are reworked is always part of the process for large systems Iteration can be applied to any of the generic process models Two (related) approaches Incremental development Spiral development Computer Science Software Engineering Slide 24 Incremental development q q q Rather than deliver the system as a single delivery, the development and delivery is broken down into increments with each increment delivering part of the required functionality User requirements are prioritised and the highest priority requirements are included in early increments Once the development of an increment is started, the requirements are frozen though requirements for later increments can continue to evolve Computer Science Software Engineering Slide 25 Incremental development D efine outline requirements A ssign requirements to increments D esign system architecture D evelop system increment V alidate increment Integrate increment V alidate system Final system Systemincomplete Computer Science Software Engineering Slide 26 Incremental development advantages q q q q Customer value can be delivered with each increment so system functionality is available earlier Early increments act as a prototype to help elicit requirements for later increments Lower risk of overall project failure The highest priority system services tend to receive the most testing Computer Science Software Engineering Slide 27 Extreme programming q q New approach to development based on the development and delivery of very small increments of functionality Relies on constant code improvement, user involvement in the development team and pairwise programming Computer Science Software Engineering Slide 28 Spiral development q q q q Process is represented as a spiral rather than as a sequence of with activities backtracking Each loop in the spiral represents a phase in the process. No fixed phases such as specification or design loops in the spiral are chosen depending on what is required Risks are explicitly assessed and resolved throughout the process Computer Science Software Engineering Slide 29 Spiral model of the software process Determine objectives alternatives and constraints Risk analysis Risk analysis Risk analysis Prototype 3 Prototype 2 Operational proto ype Evaluate alternatives identify, resolve risks REVIEW R equirem ents plan Life-cycle plan Risk anal sis Protoy type 1 Concept of Operation Simulations, models, benchm arks S/W requirem ents Product design Developm ent plan Integration and test plan Plan next phase Code Unit test Design V&V Integration test Acceptance test Develop, verify Service next-level product Slide 30 R equirem ent validation Detailed design Computer Science Software Engineering Spiral model sectors q Objective setting Specific objectives for the phase are identified Risks are assessed and activities put in place to reduce the key risks A development model for the system is chosen which can be any of the generic models The project is reviewed and the next phase of the spiral is planned q Risk assessment and reduction q Development and validation q Planning Computer Science Software Engineering Slide 31 Software specification q q The process of establishing what services are required and the constraints on the system s operation and development Requirements engineering process Feasibility study Requirements elicitation and analysis Requirements specification Requirements validation Computer Science Software Engineering Slide 32 The requirements engineering process F easibility stud y Requirements elicitation and analysis R equirements specification Requirements va lidation System models U and system ser requirements Requirements document F easibility report Computer Science Software Engineering Slide 33 Software design and implementation q q The process of converting the system specification into an executable system Software design Design a software structure that realises the specification q Implementation Translate this structure into an executable program q The activities of design and implementation are closely related and may be inter-leaved Computer Science Software Engineering Slide 34 Design process activities q q q q q q Architectural design Abstract specification Interface design Component design Data structure design Algorithm design Computer Science Software Engineering Slide 35 The software design process Requir ements specifica tion Design acti vities Ar chitectur al design Abstr act specifica tion Interface design Component design Da ta structur e design Algorithm design System architectur e Softw are specifica tion Interface specifica tion Component specifica tion Design pr oducts Da ta structur e specifica tion Algorithm specifica tion Computer Science Software Engineering Slide 36 Design methods q q q Systematic approaches to developing a software design The design is usually documented as a set of graphical models Possible models Data-flow model Entity-relation-attribute model Structural model Object models Computer Science Software Engineering Slide 37 Programming and debugging q q q Translating a design into a program and removing errors from that program Programming is a personal activity - there is no generic programming process Programmers carry out some program testing to discover faults in the program and remove these faults in the debugging process Computer Science Software Engineering Slide 38 The debugging process Lc te oa er r ro Din eg s er rr pir ro e a Rpir ea er r ro R-e t et s po r m r ga Computer Science Software Engineering Slide 39 Software validation q q q Verification and validation is intended to show that a system conforms to its specification and meets the requirements of the system customer Involves checking and review processes and system testing 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 Software Engineering Slide 40 Computer Science The testing process Unit testing Module testing Sub-system testing System testing Acceptance testing Component testing Computer Science Integration testing User testing Slide 41 Software Engineering Testing stages q Unit testing Individual components are tested Related collections of dependent components are tested Modules are integrated into sub-systems and tested. The focus here should be on interface testing Testing of the system as a whole. Testing of emergent properties Testing with customer data to check that it is acceptable q Module testing q Sub-system testing q System testing q Acceptance testing Computer Science Software Engineering Slide 42 Testing phases R equirements specifica tion System specification System de gn si D etailed de sign A cceptance te plan st System inte gration te plan st Sub-system inte gration te plan st M odule and unit code and tess Service A cceptance te st System inte gration test Sub-system inte gration test Computer Science Software Engineering Slide 43 Software evolution q q q 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 between development and evolution (maintenance) this is increasingly irrelevant as fewer and fewer systems are completely new Software Engineering Slide 44 Computer Science System evolution Define system requirements Assess existing systems Propose system changes Modify systems Existing systems New system Computer Science Software Engineering Slide 45 Automated process support (CASE) q q Computer-aided software engineering (CASE) is software to support software development and evolution processes Activity automation Graphical editors for system model development Data dictionary to manage design entities Graphical UI builder for user interface construction Debuggers to support program fault finding Automated translators to generate new versions of a program Computer Science Software Engineering Slide 46 Case technology q Case technology has led to significant improvements in the software process though not the order of magnitude improvements that were once predicted Software engineering requires creative thought - this is not readily automatable Software engineering is a team activity and, for large projects, much time is spent in team interactions. CASE technology does not really support these Computer Science Software Engineering Slide 47 CASE classification q q Classification helps us understand the different types of CASE tools and their support for process activities Functional perspective Tools are classified according to their specific function Tools are classified according to process activities that are supported Tools are classified according to their organisation into integrated units q Process perspective q Integration perspective Computer Science Software Engineering Slide 48 Functional tool classification Computer Science Software Engineering Slide 49 Reengineering tools Testing tools Debugging tools Program analysis tools Language-processing tools Method support tools Prototyping tools Configuration management tools Change management tools Documentation tools Editing tools Planning tools Specification Design Implementation Activity-based classification Verification and Validation CASE integration q Tools Support individual process tasks such as design consistency checking, text editing, etc. q Workbenches Support a process phase such as specification or design, Normally include a number of integrated tools q Environments Support all or a substantial part of an entire software process. Normally include several integrated workbenches Computer Science Software Engineering Slide 51 Tools, workbenches, environments CASE technolo gy Tools W orkbenches Environments Editors Compilers File comparators Integrated environments Process-centred environments Analysis and design Programming Testing Multi-method workbenches Single-method workbenches General-purpose workbenches Language-specific workbenches Computer Science Software Engineering Slide 52 Key points q q q q Software processes are the activities involved in producing and evolving a software system. They are represented in a software process model General activities are specification, design and implementation, validation and evolution Generic process models describe the organisation of software processes Iterative process models describe the software process as a cycle of activities Computer Science Software Engineering Slide 53 Key points q q q q q 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 CASE technology supports software process activities Computer Science Software Engineering Slide 54

Find millions of documents here - Study Guides, Homework Solutions, Papers, Exam Answer Keys and more. Course Hero has millions of course related materials that will enable you to learn better, faster and get an A in all your courses.
Below is a small sample set of documents: