What is Agile? What is Scrum?

WHAT IS AGILE? WHAT IS SCRUM?



In software development Agile is a set of values and principles formulated by a group of the industry leading figures in 2001.




Scrum is a concrete software development model that can be traced back to 1995 and was created by two of the original signatories of Agile Manifesto. Scrum supports Agile values. Note that Scrum is for project management, it is not a development methodology.



The early approach to software project management usually referred to as "waterfall model" implies a sequence of clearly defined steps necessary to complete any project: define, plan, organize, execute and then close.



This represents a very neat, simple and above all convenient abstraction from the project management theorist point of view. When one stage follows another it is possible to define clear inputs and outputs for each stage, isolate and identify techniques and tools that are most useful at every phase. This is a clear example of reductionism in tackling project management complexity: keep splitting the whole into smaller bits until you get to understand each bit in isolation and then hopefully you will master the mechanics of their totality.



But as soon as the waterfall abstraction was presented it started to leak. Firstly it turned out that real-life process cannot be clearly cut into stages, often definition is still changed on what it seems to be planning, organization or even execution stage. So, in theory, the stages were allowed to overlap and theoreticians started drawing all sorts of diagrams there it's possible to see how the definition stage gradually runs out as execution starts picking up during the organization stage. Then, again only in theory, it is possible to accurately estimate during the planning stage how long it is going to take to develop a piece of software. Obviously, in actual practice, the estimates and other plans have to be tweaked right through the execution phase which gave birth to a string of complex yet not very meaningful methods as Earned Value Management.



The chronic problems with the waterfall abstraction gave birth to a number of "agile" project management methods (Agile, Scrum, XP Programming etc) that despite many differences at the more detailed level use the same fundamental principles to tackle product development complexity:



* The project is organized as a number of small iterations through the classic project stages (definition, planning, organization, execution and closure).

* Each iteration aims at a relatively small yet semantically complete increment in product functionality or non-functional characteristics.

* Strong end-user involvement throughout the project.



Since every iteration goes through a separate definition and planning stage the time horizon for various estimation and planning activities is greatly reduced. It helps achieve greater accuracy, hence make it easier to access feasibility, measure value and costs etc.



Small increments help controlling the scope, evaluate utility of the changes and keep users involved since there is always a fresh version of fully functioning product. It is also much easier to organize a number of teams working on a large project simultaneously when increments are kept small, this really helps tackling task dependencies.



Agile is a methodology, and there are various ways to define what agile is. To a large extent, if it involves constant unit testing and the ability to quickly adapt when the business needs change then it is probably agile. The opposite is the waterfall method.



There are various implementations that are codified by consultants, such as Xtremem Programming, Scrum and RUP (Rational Unified Process).



Agile is a collection of practices. While there is no formal definition of the collection of agile practices, there are studies that have measured the effectiveness of various agile practices.



Broadly, the agile practices can be categories into two groups, management practices and engineering practices. SCRUM is the most popular set of management practices. XP or Extreme Programming is the best known set of engineering practices.



If an agile team only employees the management practices, i.e., SCRUM, they are likely to be unable to maintain a sustainable pace for an indefinite period of time. For example, without automated functional tests, it will take longer and longer to validate each iteration. If you don't use pairing or Test Driven Development, you are likely to find your defects grow out of control.



Management practices enable the team to collaboration successfully with the business partner. Prioritizing what need to be done, working collaboratively against scope in priority order. SCRUM, by itself, will provide benefit immediately. Management practices tend to be the easiest to learn and put into practices.



Examples of management practices are open workspace, product owner, prioritized product backlog, iteration, iteration and release planning meetings, show & tell etc.



While the engineering practices are more difficult to learn and execute well, they are essential if a team is to maintain a sustainable pace of high quality software. Examples of engineering practices are developer pairing, test drive development, simple evolutionary design, automated functional and performance tests, continuous integration and collective code ownership.



Agile provides alternative ways to achieve the same business goals. IMO agile is less intuitive but works better in practice. The agile approach says it's impossible to know every detail up front for all but the smallest/simplest projects and that the project should be able to accommodate surprises and updated requirements. Further, by completing and verifying software features in order of importance, touching all relevant architectural layers along the way, agile can make it more possible to have a useful product by the deadline demanded by the business side.



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