SYSTEMS ANALYSIS project
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04_SystemsAnalysis-Fall2019-Week41.pdf
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ISMM1-UC 752: SYSTEMS ANALYSIS
Fall 2019 – Lecture 4 Instructor: Dr. Antonios Saravanos
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Dilbert Cartoon – Failure
• https://www.youtube.com/watch?v=huEpQj5FcGI
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The Agile System Development Methodology
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Manifesto for Agile Software Development
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Manifesto for Agile Software Development
Source: http://www.applitude.se/images/inc_vs_ite.png
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Manifesto for Agile Software Development
Source: http://www.applitude.se/images/inc_vs_ite.png
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Principles Behind the Agile Manifesto
Source: http://agilemanifesto.org/principles.html
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Principles Behind the Agile Manifesto
Source: http://agilemanifesto.org/principles.html
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Principles Behind the Agile Manifesto
Source: http://agilemanifesto.org/principles.html
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The Paradigm Shift
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Relationship Between Agile Values, Principles, and Practices
Source: http://i.msdn.microsoft.com/dynimg/IC511953.jpg
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Popular Agile Software Development Frameworks
• Scrum • Extreme programming (XP) • Crystal • Dynamic Systems Development Method (DSDM) • Feature-Driven Development (FDD)
• Source: Pro Agile .NET Development with Scrum (p. 8-11)
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Principles of Scrum
• Regularly deliver value • Adjust process according to results • Allow business to change their mind when needed • Allow the development team the time to complete their commitments to the
business
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Scrum Values
• Commit to the goal • Focus on completing your commitment • Be open and share with your team • Respect your team • Have the courage to act for the best interests of achieving your goal
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Roles
• Product Owner (Business) – Represents the customer – Controls the product backlog – Signs off on deliverables
• The Scrum Master – Ensures scrum values are understood and kept – Tracks progress and finds ways to overcome obstacles
• The Development Team – The people actually responsible for delivering the system – Self-organizing unit – Members of the team are generalists not specialists
• Cross functional (Each member of the team knows all aspects of the product that is being developed)
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Scrum Values
• Commit to the goal • Focus on completing your commitment • Be open and share with your team • Respect your team • Have the courage to act as necessary
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The Scrum Process Lifecycle
Source: Pro Agile .NET Development with Scrum (p.14)
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Product Backlog
• An ordered list of desired product functionality
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Sprint
• Scrum is comprised of a series of time blocks called sprints (timeboxes) • The goal of a sprint is to deliver working software • The duration of a sprint is typically two to four weeks in length • Sprints are isolated from change and represent a commitment by both the
business and the developer
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Sprint Backlog
• A list of tasks to be completed during the sprint • A subset of the product backlog
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Daily Scrum Meetings
• Team meets daily to touch base • Meetings are usually short short (15-20 minutes in length) • Provide an opportunity to discuss what has happened since the last meeting • What we will take place next • Any development obstacles
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Sprint Review
• A meeting during which the team presents the increment that has been built during the sprint
• Time of meeting varies on perspective but can range form from 2 to 4 hours
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Sprint Retrospective
• Traditionally takes place after the sprint review • Provides an opportunity to go over the sprint and reflect on activities • Provides an opportunity to think about what the team should:
– start doing – stop doing – continue doing
• The meeting should be comprised of the: – (entire) development team – scrum master – product owner – Sprint retrospectives usually last for about an hour but duration varies
according to need
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Requirements with Agile
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User Stories
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• http://www.thoughtworks.com/products/docs/mingle/13.4/help/explore_mingle_topic_whats_a_card.html
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User Stories
• A short description of user-valued function • Traditionally hand written on a green index card • Written by the business • Regarded as a “promise” to discuss • There is usually a cost estimate attached in points on the bottom right
corner • Acceptance test is written on the reverse of the card • Not static but rather updated during the development process • Traditionally ripped-up after they have been implemented • Note that user stories are not:
– use-cases – scenarios
• Also note that user stories do not meet IEEE 830 Specification Requirements
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Creating Stories
• The business writes the story • The developer estimates a cost • The business prioritizes the stories • Capacity determines how many stories will be completed in the next
iteration • Stories are decomposed into tasks by the development team • Business and developer meet to discover details which are captured as the
acceptance test • Stories should have the following characteristics:
– Independent from other stories – Negotiable – Valuable – Estimable – Small and Testable
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Be Independent from Other Stories
• Stories must be independent of other ones to ensure • Decompose stories into smaller ones if needed
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Negotiable
• The story is an opportunity for a conversation not a contract • You should record any questions that need to be asked
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Valuable
• The story holds a value to the users of your system • Technical perspectives should be framed in a way that shows user value
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Estimable
• If developers cannot place an estimate to a user story then some thought should be placed why this is the case.
• Do the developers lack the knowledge to develop such a story • Is the story so large (“epic”) that it needs to be broken down into smaller
stories
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Estimable
• If developers cannot place an estimate to a user story then some thought should be placed why this is the case.
• Do the developers lack the knowledge to develop such a story • Is the story so large (“epic”) that it needs to be broken down into smaller
stories • Are there any benefits of epic stories?
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Estimable
• If developers cannot place an estimate to a user story then some thought should be placed why this is the case.
• Do the developers lack the knowledge to develop such a story • Is the story so large (“epic”) that you can’t really accurately estimate its
completion it needs to be broken down into smaller stories • Are there any benefits of epic stories?
– They can give you a big picture of what is coming in the near future
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Small and Testable
• If a story is epic then it needs to be broken down into smaller more manageable stories.
• It should be possible to create an automated test case for each story • The test case for each story should be run easily and often
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How to write stories
• You can collect stories using elicitation techniques such as: – User interviews – Questionnaires – Observation – Focus groups – Collaborative workshops
• Then use goal driven analysis techniques to help focus the elicitation – Start by creating a list of user roles
• Its okay to write epic stories as they can give you an understanding of the landscape, just remember they will need to be broken down
• Don’t focus on the UI details when creating the stories • Don’t order the stories while your creating them
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User Story Template
• As a ... • I want ... • So that ...
• Source: http://www.andrewfuqua.com/2011/02/scrum-fundamental-user-stories.html
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Acceptance Criteria Template
• Acceptance criteria defines the conditions of acceptance – Knowing when we are done
• Provides the developer a set of conditions that must be finished before the user story can be considered completed.
• Given ... • When ... • Then ...
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So the user story card who appear…
• Source: http://blogs.kent.ac.uk/agile/files/2009/09/Slide1-264x300.jpg
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• http://www.agilemodeling.com/artifacts/userStory.htm
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• http://www.agilemodeling.com/artifacts/userStory.htm
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Why use user stories?
• All us to focus at the precise needs of the business • They are understood by the business (remember the business writes the
stories and the developer estimates cost) • They are lightweight
– easy to write – responsive to change
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• Remember agile development is about embracing a set of values that underpin the way we work!
• You don’t have to follow a specific framework to be agile!
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Extreme Programming
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XP. The basic problem of software development.
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Kent Beck
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Martin Fowler. Have we seen one of his products?
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Extreme programming
• Perhaps the best-known and most widely used agile method along with Scrum.
• Extreme Programming (XP) takes an ‘extreme’ approach to iterative development. – New versions may be built several times per day; – Increments are delivered to customers every 2
weeks; – All tests must be run for every build and the build is
only accepted if tests run successfully.
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XP Values
• Communication • Simplicity • Feedback • Courage
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The XP release cycle
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The XP release cycle
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The XP release cycle
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Extreme programming practices 1
Incremental planning
Requirements are recorded on Story Cards and the Stories to be included in a release are determined by the time available and their relative priority. The developers break these Stories into development ‘Tasks’.
Small Releases The minimal useful set of functionality that provides business value is developed first. Releases of the system are frequent and incrementally add functionality to the first release.
Simple Design Enough design is carried out to meet the current requirements and no more.
Test first development
An automated unit test framework is used to write tests for a new piece of functionality before that functionality itself is implemented.
Refactoring All developers are expected to refactor the code continuously as soon as possible code improvements are found. This keeps the code simple and maintainable.
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Extreme programming practices 2
Pair Programming Developers work in pairs, checking each other’s work and providing the support to always do a good job.
Collective Ownership The pairs of developers work on all areas of the system, so that no islands of expertise develop and all the developers own all the code. Anyone can change anything.
Continuous Integration
As soon as work on a task is complete it is integrated into the whole system. After any such integration, all the unit tests in the system must pass.
Sustainable pace Large amounts of over-time are not considered acceptable as the net effect is often to reduce code quality and medium term productivity
On-site Customer A representative of the end-user of the system (the Customer) should be available full time for the use of the XP team. In an extreme programming process, the customer is a member of the development team and is responsible for bringing system requirements to the team for implementation.
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XP and agile principles
• Incremental development is supported through small, frequent system releases.
• Customer involvement means full-time customer engagement with the team.
• People not process through pair programming, collective ownership and a process that avoids long working hours.
• Change supported through regular system releases. • Maintaining simplicity through constant refactoring of
code.
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Customer involvement
• Customer involvement is a key part of XP where the customer is part of the development team.
• The role of the customer is: – To help develop stories that define the requirements – To help prioritise the features to be implemented in
each release – To help develop acceptance tests which assess
whether or not the system meets its requirements.
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Requirements scenarios
• In XP, user requirements are expressed as user stories.
• These are written on cards and the development team break them down into implementation tasks. These tasks are the basis of schedule and cost estimates.
• The customer chooses the stories for inclusion in the next release based on their priorities and the schedule estimates.
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XP and change
• Conventional wisdom in software engineering is to design for change. It is worth spending time and effort anticipating changes as this reduces costs later in the life cycle.
• XP, however, maintains that this is not worthwhile as changes cannot be reliably anticipated.
• Rather, it proposes constant code improvement (refactoring) to make changes easier when they have to be implemented.
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Refactoring
• Refactoring is the process of code improvement where code is reorganised and rewritten to make it more efficient, easier to understand, etc.
• Refactoring is required because frequent releases mean that code is developed incrementally and therefore tends to become messy.
• Refactoring should not change the functionality of the system.
• Automated testing simplifies refactoring as you can see if the changed code still runs the tests successfully.
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Testing in XP
• Test-first development. • Incremental test development from scenarios. • User involvement in test development and
validation. • Automated test harnesses are used to run all
component tests each time that a new release is built.
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Test-first development
• Writing tests before code clarifies the requirements to be implemented.
• Tests are written as programs rather than data so that they can be executed automatically. The test includes a check that it has executed correctly.
• All previous and new tests are automatically run when new functionality is added. Thus checking that the new functionality has not introduced errors.
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Pair programming
• In XP, programmers work in pairs, sitting together to develop code.
• This helps develop common ownership of code and spreads knowledge across the team.
• It serves as an informal review process as each line of code is looked at by more than 1 person.
• It encourages refactoring as the whole team can benefit from this.
• Measurements suggest that development productivity with pair programming is similar to that of two people working independently.
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Problems with XP
• Customer involvement – This is perhaps the most difficult problem. It may be
difficult or impossible to find a customer who can represent all stakeholders and who can be taken off their normal work to become part of the XP team. For generic products, there is no ‘customer’ - the marketing team may not be typical of real customers.
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Problems with XP
• Architectural design – The incremental style of development can mean that
inappropriate architectural decisions are made at an early stage of the process.
– Problems with these may not become clear until many features have been implemented and refactoring the architecture is very expensive.
• Test complacency – It is easy for a team to believe that because it has many tests,
the system is properly tested. – Because of the automated testing approach, there is a tendency
to develop tests that are easy to automate rather than tests that are ‘good’ tests.
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Key points
• Extreme programming includes practices such as systematic testing, continuous improvement and customer involvement.
• Customers are involved in developing requirements which are expressed as simple scenarios.
• The approach to testing in XP is a particular strength where executable tests are developed before the code is written.
• Key problems with XP include difficulties of getting representative customers and problems of architectural design.
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XP. The basic problem of software development. • Schedule slips—the day for delivery comes, and you have to tell the
customer that the software won't be ready for another six months. • Project canceled—after numerous slips, the project is canceled without ever
going into production. • System goes sour—the software is successfully put into production, but
after a couple of years the cost of making changes or the defect rate rises so much that the system must be replaced.
• Defect rate—the software is put into production, but the defect rate is so high that it isn't used.
• Business misunderstood—the software is put into production, but it doesn't solve the business problem that was originally posed.
• Business changes—the software is put into production, but the business problem it was designed to solve was replaced six months ago by another, more pressing, business problem.
• False feature rich—the software has a host of potentially interesting features, all of which were fun to program, but none of which makes the customer much money.
• Staff turnover—after two years, all the good programmers on the project begin to hate the program and leave.
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