Chapter 3: Agile Software Development
What is the scrum approach?
A general agile method but its focus is on managing iterative development rather than specific agile practices.
What is the XP practice of an 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.
What is the extreme programming practice of refactoring?
All developers are expected to re-factor the code continuously as soon as possible code improvements are found. This keeps the code simple and maintainable.
What is the extreme programming practice of 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.
What is the XP practice of continuous integration?
As soon as the 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.
What are large systems?
Brownfield systems, which means they include and interact with a number of existing systems. Teams usually work in different places and sometimes different time zones
What is the extreme programming practice of simple design?
Enough design is carried out to meet the current requirements and no more.
What is the principle of embrace change?
Expect the system requirements to change and so design the system to accommodate these changes.
What is the XP practice of sustainable pace?
Large amounts of overtime are not considered acceptable as the net effect is often to reduce code quality and medium term productivity
What is the XP practice of collective ownership?
The pairs of developers work on all areas of the system, so that no islands of expertise develop and all the developers take responsibility for all of the code. Anyone can change anything.
What is plan-driven development?
-Based around separate development stages with the outputs to be produced at each of these stages planned in advance -Iteration occurs within activities
What are some problems with agile methods?
-Difficult to keep interest of customers who are involved in the process -Team members may be unsuited to the intense involvement -Prioritizing changes can be hard with multiple stakeholders -Maintaining simplicity requires extra work -Contracts may be a problem
Where can the agile method be applied?
-Product development where a software company is developing a small or medium-sized product for sale. -Custom system development within an organization where there is a clear commitment from the customer to become involved in the development process
What are the benefits of Scrum?
-Product is broken down into a set of manageable and understandable chunks -The whole team have visibility of everything and consequently team communication is improved -Customers see on-time delivery of increments and gain feedback on how the product works -Trust between customers and developers
What are some difficulties of XP testing?
-Programmers prefer programming to testing and sometimes they take short cuts when writing tests. -Some test can be very difficult to write incrementally -Difficult to judge the completeness of a set of tests
What is pair programming?
-Programmers work in pairs, sitting together to develop code. -Encourages refactorig 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
What are some examples of refactoring?
-Re-organization of a class hierarchy to remove duplicate code -Tidying up and renaming attributes and methods to make them easier to understand -The replacement of inline code with calls methods that have been included in a program library
What is rapid software development?
-Specification, design and implementation are inter-leaved -System is developed as a series of versions with stakeholders involved in version evaluation -User interfaces are often developed using an IDE and graphical toolset
What is a sprint cycle?
-Sprints are fixed length, normally 2-4 weeks. -Starting point for planning is the product backlog.
What is extreme programming (XP)?
-Takes an 'extreme' approach to iterative development -New versions may be built several times per day -Increments delivered every 2 weeks -All test must be run for every build and the build is only accepted if tests run successfully
What are XP testing features?
-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
What are the three phases in Scum?
-The initial phase is an outline planning phase where you establish the general objectives for the project and design the software architecture -Sprint cycles -Project closure phase, complete required documentation
What is the principle of customer involvement?
Customers should be closely involved throughout the development process. Their roles is to provide and prioritize new system requirements and to evaluate the iterations of the system.
What is the extreme programming practice of pair programming?
Developers work in pairs, checking each other's work and providing the support to always do a good job.
What is the principle of maintain simplicity?
Focus on simplicity in both the software being developed and in the development process. Wherever possible, actively work to eliminate complexity from the system.
What is refactoring?
Programming team look for possible software improvements and make these improvements even where there is no immediate need for them.
What is the extreme programming practice of incremental planning?
Requirements are recorded on story cards and stories to be included in a release are determined by the time available and their relative priority.
What is agile development?
Specification, design, implementation and testing are interleaved and outputs from the development process are decided through a process of negotiation during the software development process
What is test automation?
Test are written as executable components before the task is implemented.
What is the extreme programming practice of 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.
What is customer involvement?
The role of the customer in the testing process is to help develop acceptance tests for the stories that are to be implemented in the next release of the system. The customer who is part of the team writes tests as development proceeds.
What is the principle of people not process?
The skills of the development team should be recognized and exploited. Team members should be left to develop their own ways of working without prescriptive processes.
What is the principle of incremental delivery?
The software is developed in increments with the customer specifying the requirements to be included in each increment.
What is the role of the Scrum master?
To protect the development team from external distractions with all communications done through the master between customer and organization
What is the aim of agile methods?
To reduce overheads in the software process and to be able to respond quickly to changing requirements without excessive rework
What is 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.
What does the Scrum master do?
a facilitator who arranges daily meetings, tracks the backlog of work to be done, records decisions, measures progress against the backlog and communicates with customers and management outside of the team
What is 'Scaling out' concerned with?
how agile methods can be introduced across a large organization with many years of software development experience
What is 'Scaling up' concerned with?
using agile methods for developing large software systems that cannot be developed by a small team