Lesson 3

Why might it be difficult for large companies to adopt agile methods?

- Rigid procedures - Wide range of skill levels, vs mostly high level - Inexperienced project managers not wanting to take the risk of using a method they don't know

Typically how long are scrum sprints?

2-4 weeks

What is scrum?

A general agile method but its focus is on managing iterative development

XP Principle: 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.

XP Principle: 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.

XP Principle: 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.

XP Principle: Simple design

Enough design is carried out to meet the current requirements and no more.

Describe the agile principle Embrace change

Expect the system requirements to change and so design the system to accommodate these changes.

What is seen as the most well-known and widely used agile method?

Extreme Programming

What is Extreme Programming?

Extreme Programming (XP) takes an 'extreme' approach to iterative development.

What is scaling out in agile development?

How agile methods can be introduced across a large organization with many years of software development experience.

Deciding between Agile/Plan; Is the system subject to external regulation?

If a system has to be approved by an external regulator (e.g.theFAA approve software that is critical to the operation of an aircraft) then you will probably be required to produce detailed documentation as part of the system safety case.

XP Principle: Sustainable pace

Large amounts of overtime are not considered acceptable as the net effect is often to reduce code quality and medium term productivity

XP Principle: 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.

XP Principle: 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.

Deciding between Agile/Plan; What type of system is being developed?

• Plan-driven approaches maybe required for systems that require a lot of analysis before implementation (e.g. real-time system with complex timing requirements).

What are the principles of agile methods?

- Customer involvement - Incremental delivery - People not process - Embrace change - Maintain simplicity

XP Principle: 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.

what are automated test frameworks?

A system that makes it easy to write executable tests and submit a set of tests for execution.

Deciding between Agile/Plan; How large is the system that is being developed?

Agile methods are most effective when the system can be developed with a small co-located team who can communicate informally. This may not be possible for large systems that require larger development teams so a plan-driven approach may have to be used.

Describe the agile principle Customer involvement.

Customers should be closely involved throughout the development process. Their role is provide and prioritize new system requirements and to evaluate the iterations of the system.

XP Principle: Pair programming

Developers work in pairs, checking each other's work and providing the support to always do a good job.

Describe the agile principle 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 the scrum selection phase?

Involves all of the project team who work with the customer to select the features and functionality to be developed during the sprint.

What is an example of an automated test framework?

Junit

If all of your tests pass, does that mean you have 0 bugs in your system?

NO!

What is the scrum master used for?

Protect the development team from external distractions. The 'Scrum master' is 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 type of development is often the most important requirement for software systems?

Rapid development and delivery

XP Principle: 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'.

What is test automation?

Tests are written as executable components before the task is implemented ▪ These testing components should be stand-alone, should simulate the submission of input to be tested and should check that the result meets the output specification.

Describe the agile principle 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.

Describe the agile principle Incremental delivery

The software is developed in increments with the customer specifying the requirements to be included in each increment.

What is the product backlog in scrum?

The starting point for planning. A list of word to be done on the project.

During software development with scrum, how is communication handled?

The team is isolated from the customer and the organization, with all communications channelled through the so-called 'Scrum master'

What happens at the end of a sprint?

The work done is reviewed and presented to stakeholders. The next sprint cycle then begins.

What are the main benefits of automated testing?

There is always a set of tests that can be quickly and easily executed ▪ Whenever any functionality is added to the system, the tests can be run and problems that the new code has introduced can be caught immediately.

(T/F) Most projects include elements of plan-driven and agile processes.

True

(T/F) Scrum sprints are fixed in length

True

Pair Programming: (T/F) Measurements suggest that development productivity with pair programming is similar to that of two people working independently.

True

What is scaling up in agile development?

Using agile methods for developing large software systems that cannot be developed by a small team.

Deciding between Agile/Plan; What technologies are available to support system development?

• Agile methods rely on good tools to keep track of an evolving design

Deciding between Agile/Plan; How is the development team organized?

• If the development team is distributed or if part of the development is being outsourced, then you may need to develop design documents to communicate across the development teams.

Deciding between Agile/Plan; How good are the designers and programmers in the development team?

• It is sometimes argued that agile methods require higher skill levels than plan-based approaches in which programmers simply translate a detailed design into code

Deciding between Agile/Plan; What is the expected system lifetime?

• Long-life time systems may require more design documentation to communicate the original intentions of the system developers to the support team.

Deciding between Agile/Plan; Are there cultural or organizational issues that may affect the system development?

• Traditional engineering organizations have a culture of plan-based development, as this is the norm in engineering.

Why is Rapid development and delivery so necessary?

▪ Businesses operate in a fast -changing requirement and it is practically impossible to produce a set of stable software requirements ▪ Software has to evolve quickly to reflect changing business needs.

What are the key differences between agile and the older methods of the 90s?

▪ Focus on the code rather than the design ▪ Are based on an iterative approach to software development ▪ Are intended to deliver working software quickly and evolve this quickly to meet changing requirements.

What are some things to consider when deciding on a balance between agile and plan driven?

▪ Is it important to have a very detailed specification and design before moving to implementation? If so, you probably need to use a plan-driven approach. ▪ Is an incremental delivery strategy, where you deliver the software to customers and get rapid feedback from them, realistic? If so, consider using agile methods.

What are some aspects of XP?

▪ 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.

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.

Describe 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.

What are the 3 phases in Scrum?

▪ The initial phase is an outline planning phase where you establish the general objectives for the project and design the software architecture. ▪ This is followed by a series of sprint cycles, where each cycle develops an increment of the system. ▪ The project closure phase wraps up the project, completes required documentation such as system help frames and user manuals and assesses the lessons learned from the project.

What does requirements illicitation look like in XP?

◇ In XP, a customer or user is part of the XP team and is responsible for making decisions on requirements. ◇ User requirements are expressed as scenarios or 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.

What are the motivations behind pair programming in XP?

◇ 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.

What is pair programming?

◇ In pair programming, programmers sit together at the same workstation to develop the software. ◇ Pairs are created dynamically so that all team members work with each other during the development process.

What are potential problems with using agile methods?

◇ It can be difficult to keep the interest of customers who are involved in the process. ◇ Team members may be unsuited to the intense involvement that characterises agile methods. ◇ Prioritising changes can be difficult where there are multiple stakeholders. ◇ Maintaining simplicity requires extra work. ◇ Contracts may be a problem as with other approaches to iterative development.

What is the difference between plan-driven development and agile development?

◇ Plan-driven development ▪ A plan-driven approach to software engineering is based around separate development stages with the outputs to be produced at each of these stages planned in advance. ▪ Not necessarily waterfall model - plan-driven, incremental development is possible ▪ Iteration occurs within activities. ◇ Agile development ▪ Specification, design, implementation and testing are inter-leaved and the outputs from the development process are decided through a process of negotiation during the software development process.

When is agile typically applicable?

◇ 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 and where there are not a lot of external rules and regulations that affect the software. ◇ Because of their focus on small, tightly-integrated teams, there are problems in scaling agile methods to large systems.

What is code refactoring?

◇ Programming team look for possible software improvements and make these improvements even where there is no immediate need for them. ◇ This improves the understandability of the software and so reduces the need for documentation. ◇ Changes are easier to make because the code is well- structured and clear. ◇ However, some changes requires architecture refactoring and this is much more expensive.

What is the aim of agile methods?

◇ The aim of agile methods is to reduce overheads in the software process (e.g. by limiting documentation) and to be able to respond quickly to changing requirements without excessive rework.

What are benefits to using Scrum?

◇ The product is broken down into a set of manageable and understandable chunks. ◇ Unstable requirements do not hold up progress. ◇ 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 is established and a positive culture is created in which everyone expects the project to succeed.

How is the customer involved in agile development?

◇ 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. All new code is therefore validated to ensure that it is what the customer needs. ◇ However, people adopting the customer role have limited time available and so cannot work full-time with the development team. They may feel that providing the requirements was enough of a contribution and so may be reluctant to get involved in the testing process.

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. The test includes a check that it has executed correctly. ▪ Usually relies on a testing framework such as Junit. ◇ All previous and new tests are run automatically when new functionality is added, thus checking that the new functionality has not introduced errors.