Professional standards 2-1-1 Fundamentals of computer systems 3 GCSE OCR Computing A451.
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Transcript of Professional standards 2-1-1 Fundamentals of computer systems 3 GCSE OCR Computing A451.
Professional standards
2-1-1 Fundamentals of computer systems
3
GCSEOCRComputingA451
Objectives
• Understand the need for standards in the development and maintenance of computer systems
• Give examples of standards in computer systems
• Understand how standards help to ensure that computer systems are free of errors, easy to maintain and easy to use
Professional standards
2-1-1 Fundamentals of computer systems
Who needs standards?• Some standards come about through constant
usage
• In the UK, we drive on the left• In many other countries, people drive on the
right
• Does this ever cause a problem?
Professional standards
2-1-1 Fundamentals of computer systems
De facto standards• De facto standards are ones which
come about through common usage
• Americans write dates in the format MM-DD-YYYY
• How do we write them?
• Could this ever cause problems in software usage?
• Think of some other de facto standards in everyday life and in the context of computing. Are they the same all over the world?
Professional standards
2-1-1 Fundamentals of computer systems
Software development• Many computer systems involve tens of thousands
or even millions of lines of code
• Teams of programmers work on the project, each developing a small part of the system
• People leave, teams change, and new programmers must take over in the middle of a project
• Good organisation, “rules” and standards are essential!
Professional standards
2-1-1 Fundamentals of computer systems
Stages in creating a computer system
Analysis
Design
ProgrammingTesting
Maintenance
Professional standards
2-1-1 Fundamentals of computer systems
Software development standards• How to document what the system needs to do
• How to break the system up into small parts that can be developed by teams of programmers
• How to allocate staff to teams
• How to keep track of changes
• How to code programs
• How to test
• How to document the whole system
Professional standards
2-1-1 Fundamentals of computer systems
Standards in Analysis and Design• Companies involved in the creation of complex
computer systems don’t start from scratch in documenting their design
• There will be professional standards defining the structure of the document, ensuring that all essential areas are covered
• You probably know yourself that it is much easier to write a lengthy document explaining your ideas, when you are given a structure to work to
Professional standards
2-1-1 Fundamentals of computer systems
Worksheet 4• Coding standards
• Suggest how this program could be made easier to understand and amend
• Then look at Worksheet 5
Professional standards
2-1-1 Fundamentals of computer systems
Programming standards• Even a small team of programmers working on a
class project would find it difficult to come up with a maintainable system if they had no agreed standards
Professional standards
2-1-1 Fundamentals of computer systems
Developing standards• What aspects of the programming and testing need
to be agreed on?
• Suggest some standards that a team of prgrammers might agree before they start
Professional standards
2-1-1 Fundamentals of computer systems
Standards for coding programs• Comments in the code
• Variable names and naming conventions
• Passing information from one module to another
• Formatting the code
• Version names and numbers
Suggest some “rules” for certain comments that MUST be included in every module
Suggest some “rules” for variable names
Professional standards
2-1-1 Fundamentals of computer systems
Example of standards for program comments• Every source code file should begin with a comment
block describing the content and its purpose
• The author and any revision authors should be identified
• The date of original code and all revisions should be given
• Comment blocks should be delineated as follows: /********************************/ /Comment Lines…. /********************************/
Professional standards
2-1-1 Fundamentals of computer systems
Benefits of software standards?• Efficiency: any member of a software team can work
on any part of the software code without having to adapt to a different programming style
• Fewer errors and easier debugging: standards result in more accurate coding
• Easy to maintain: any programmer will find it relatively easy to look through the code, understand its structure and find what they are looking for when a change needs to be made
Professional standards
2-1-1 Fundamentals of computer systems
What about the user?• Users have certain expectations when they use
hardware and software
• If standards are not followed throughout a piece of software, how does this affect the user?
• When a user buys a new computer system or a new piece of software, what documentation would they expect to find?
Professional standards
2-1-1 Fundamentals of computer systems
Recap• Professional standards cover every phase of
software development – analysis, design, development, implementation and maintenance
• Adherence to standards helps make the development process faster, more efficient, and less error-prone
• Standards make the end product easier to use
Can you give examples to explain each of these points?