Extreme programming XP Projects in Computing and Information Systems A Student's Guide 0273721313 Pearson 2009
6.11 Top-down and bottom-up development
6.11.1 Introduction
If you are producing a conventional software system with a number of components for example, modules, functions, screens that can be broken down into lower levels of detail, you will have to decide whether to use a top-down or bottom-up approach for the development. These development approaches are applicable to third-generation languages where the software may be constructed with a number of functions, subroutines or procedures, fourth-generation languages, web-based appli- cations and multimedia applications all of which could be broken down into differ- ent levels of screens and sub-screens from different menus. Figure 6.7, which is an example program breakdown structure, helps to illustrate the difference between these two techniques in the following sections. The program in Figure 6.7 is a data handling system that generates long- and short-term statistical results from a data set selected by the user. 134 Chapter 6 n Software development Figure 6.7 An example program breakdown structure Order Vertical top-down Horizontal top-down Bottom-up 1 Main Menu Main Menu Long-Term Analysis 2 Data Entry Data Entry Short-Term Analysis 3 Data Analysis Data Analysis Plot Graphs 4 Long-Term Analysis Results Output Save Results to File 5 Short-Term Analysis Long-Term Analysis Data Entry 6 Results Output Short-Term Analysis Data Analysis 7 Plot Graphs Plot Graphs Results Output 8 Save Results to File Save Results to File Main Menu Table 6.3 Order of development for different approaches for example program shown in Figure 6.76.11.2 Top-down development
In a top-down approach you work your way down through the program structure, coding successively lower level modules of the program until the entire system is complete. You can achieve this in one of two ways – vertically or horizontally. In vertical top-down devel- opment you work down each branch as far as you can go before moving back up through the structure and working your way down again. In Figure 6.7, a vertical top-down approach would lead you to code the modules in the order shown in Table 6.3. Horizontal top-down development involves progressively coding an entire level of the system before moving down to the next level and so on. Table 6.3 shows how the modules would be coded in the example program shown in Figure 6.7. Vertical top-down development attempts to get particular components of the system working early rather than providing an overall working system. For example, in Figure 6.7, we would have the Data Analysis section of the system in place before any work on the Results Output section was even started. A horizontal top-down approach would test the look and feel of the system, only adding in lower detail when an entire layer of functionality was completed. In Figure 6.7 we would get an idea of how the Main Menu worked and how the three main options Data Entry, Data Analysis and Results Output would look, even though they would not actually work, before we began work on the lower working levels.Parts
» Projects in Computing and Information Systems A Student's Guide 0273721313 Pearson 2009
» Introduction What are computing projects?
» Computing project types What are computing projects?
» Programming in computing projects
» Degree structures Degree requirements
» Degree requirements for projects
» Overview Your supervisor Stakeholders
» Clients and users Stakeholders
» Evaluators and testers Stakeholders
» Overview How this book is arranged
» Taught degree projects versus research degrees
» Summary Projects in Computing and Information Systems A Student's Guide 0273721313 Pearson 2009
» A definition What is research?
» Originality What is research?
» Gaincontribution What is research?
» Knowledge and understanding What is research?
» Identify the broad area of study.
» Plan how you will perform the research.
» Gather data and information.
» Analyse and interpret these data.
» Present the results and findings.
» Review the field – i.e., perform a literature survey.
» Build a theory – based on your understanding and interpretations of the field.
» Test the theory – does it work?
» Reflect and integrate – i.e., update your ideas based on your ‘tests’ and contribute
» Intellectual discovery The research process
» Research methods Research methods
» List or multiple choice. Provides the respondent with a number of options to
» Scale. Used to rate the respondent’s feelings towards something.
» Ranking. Used to order a series of options. You should not provide too many
» Complex grid or table. Used to gather similar responses on a range of questions.
» Open-ended. Used to obtain extended, qualitative answers.
» Summary Further reading Action points
» Techniques and Information Sources
» Additional considerations Choosing a project
» Follow any guidelines precisely. Most institutions require specific information; for
» Proofread thoroughly and get someone else to check it. Any errors or omissions
» Introduction to the subject area. This will provide the reader with an under-
» Current research in the field. This will emphasise that your project is not based in
» Identify a gap. You should be able to identify some aspect of the field that requires
» Identify how your work fills the gap. Having identified a gap in the field, your
» Identify risks and solutions. It is also useful in a project proposal to highlight any
» Explicit sections Preparing a project proposal
» Reviewing your proposal Preparing a project proposal
» Exercise Projects in Computing and Information Systems A Student's Guide 0273721313 Pearson 2009
» The project process Introduction
» Definition The project’s stages
» Planning The project’s stages
» Initiation The project’s stages
» Control The project’s stages
» Closure. The project’s stages
» Complete a literature search and literature review of existing stock market prediction
» Develop a suitable artificial neural network model.
» Identify and collect suitable data for analyses and evaluation.
» Evaluate the model using appropriate statistical techniques.
» Complete final report. Setting objectives
» Step 1 – Work Breakdown Project planning
» Step 2 – Time estimates Project planning
» Step 3 – Identify milestones Project planning
» Step 4 – Activity sequencing Project planning
» Step 5 – Scheduling Project planning
» Step 6 – Re-planning Project planning
» Rolling wave planning Project planning
» Risks. Include a list of critical risk factors and means of dealing with these risks
» Organisation. If you are undertaking a group project it would be worthwhile
» Alleviate critical risks Introduction
» Identify risks Risk management
» Alleviate critical risks Risk management
» Controlling risks Risk management
» Research degrees versus taught degree projects
» A starting point Introduction
» The literature survey process
» Format of information Literature searching
» Tracing the information Literature searching
» Inter-library loans Literature searching
» Some tips for performing a literature search
» Critical evaluation Writing literature reviews
» Overview The past Introduction
» Introduction The software development life cycle SDLC
» Requirements definition Requirements capture
» Requirements specification Requirements capture
» Functional specification Requirements capture
» Design The software development life cycle SDLC
» Build The software development life cycle SDLC
» Test The software development life cycle SDLC
» Implementation The software development life cycle SDLC
» The earliest ’model’: build-and-fix
» The stage-wise and classical waterfall models conventional models
» explore the requirements of the system with the user – requirements capture, andor
» explore the technical feasibility of a system – experimental prototyping.
» Which development approach should I use?
» Which programming language should I use?
» Introduction Top-down and bottom-up development
» Top-down development Top-down and bottom-up development
» Bottom-up development Top-down and bottom-up development
» Verification Verification, validation and testing
» Validation Verification, validation and testing
» Testing Verification, validation and testing
» Who is involved with testing and evaluation?
» Test plans Miscellaneous testing types
» Quality assurance and quality control
» Exercises Projects in Computing and Information Systems A Student's Guide 0273721313 Pearson 2009
» Getting started – project initiation
» Managing the five project elements
» Introduction Dealing with problems
» Weakening Dealing with problems
» Personal problems Dealing with problems
» Hardware failure Dealing with problems
» Data availability Dealing with problems
» Discovering your workresearch has been done before
» Analyse what you are currently doing.
» Change what you are doing to achieve your aims.
» eliminate activities you don’t need to do; and
» be more efficient doing the things you have to do.
» Time management tips Procrastination
» Using your supervisor effectively
» Introduction Working in teams
» Team development Working in teams
» Managing the team Working in teams
» Teamwork tips Working in teams
» Considerations Writing and structuring reports
» Approaches to writing Writing and structuring reports
» When should I start writing?
» Identify structure. This relates to the content of your report, using a report break-
» Identify presentational style. You should also try to set standards at this stage on
» Draft the introduction. The introduction gives the reader an idea of the
» Develop the main body. The main body of your report is the next part you
» Articulate conclusions and make recommendations. Quite clearly, your conclu-
» Complete the introduction. As part of the evolutionary approach to writing,
» Write the abstract. You cannot really write a clear abstract for your report until
» Add references and appendices. Although you will be collating references and
» Arrange contents list, index. Leave the completion of an index if one is required
» Proofread, check and correct. It is vitally important to proofread your report after
» Introductionliterature review – the first chapter of your report should always be
» Main body – the content of which depends on the type of project you are un-
» Conclusionsrecommendations – summarises the contribution of the work and
» Style Writing and structuring reports
» Word processing Writing and structuring reports
» Tips Writing and structuring reports
» Presenting charts and graphs
» Common mistakes Data presentation
» Miscellaneous charts Data presentation
» Other data presentation Data presentation
» Introduction Referencing material and avoiding plagiarism
» Citing references Referencing material and avoiding plagiarism
» Listing references Referencing material and avoiding plagiarism
» Commenting program code Documenting software
» Writing user guides Documenting software
» The presentation content Visual aids
» Introduction. One or two slides that introduce you and your talk.
» Main body. The slides that constitute the bulk of your presentation and cover the
» Summaryconclusion. A few slides that summarise your presentation and perhaps
» Dealing with questions Oral presentations
» Poster preparation tips Poster presentations
» Introduction Preparation Demonstrating software
» Demonstration tips Demonstrating software
» Introduction Viva voce examinations
» Introduction Examiners and the marking of your project
» General. Examiners will look at the relevance and appropriateness of the topic
» Report. Examiners will look for clarity, consistency, an appropriate use of
» Defence. Examiners will assess the types of arguments you have made to support
» Other. Examiners will review the administrative issues of your project. For example,
» What was the research question?
» Is it a ‘good’ question? This involves a comprehensive literature review to ensure
» Has the student answered the question adequately?
» Has the student made an adequate contribution to knowledge?
» The project approach from a technical perspective i.e., not a project management
» General project considerations subject independent
» Literature reviewproject foundation Assessment criteria
» Project approachmethods Assessment criteria
» Results and contributions Assessment criteria
» Introduction Taking your project further
» Seeking funding Developing commercial software packages
» Copyright and patents Taking your project further
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