Arubrand Cluj Software

Waterfall Model
The waterfall model is a sequential approach, where each fundamental activity of a process represented as a separate phase, arranged in linear order.

In the waterfall model, you must plan and schedule all of the activities before starting working on them (plan-driven process).

Plan-driven process is a process where all the activities are planned first, and the progress is measured against the plan. While the agile process, planning is incremental and it’s easier to change the process to reflect requirement changes.
The phases of the waterfall model are: Requirements, Design, Implementation, Testing, and Maintenance.
The Nature of Waterfall Phases
In principle, the result of each phase is one or more documents that should be approved and the next phase shouldn’t be started until the previous phase has completely been finished.

In practice, however, these phases overlap and feed information to each other. For example, during design, problems with requirements can be identified, and during coding, some of the design problems can be found, etc.
The software process therefore is not a simple linear but involves feedback from one phase to another. So, documents produced in each phase may then have to be modified to reflect the changes made.

When To Use?
In principle, the waterfall model should only be applied when requirements are well understood and unlikely to change radically during development as this model has a relatively rigid structure which makes it relatively hard to accommodate change when the process in underway.

Scrum is an iterative and incremental agile software development framework for managing product development. It defines a flexible, holistic product development strategy where a development team works as a unit to reach a common goal. This method enables teams to self-organize by encouraging physical co-location or close online collaboration of all team members, as well as daily face-to-face communication among all team members and disciplines involved.
A key principle of Scrum is the dual recognition that customers will change their minds about what they want or need (requirements volatility) and that there will. Scrum adopts an evidence-based empirical approach — accepting that the problem cannot be fully understood or defined up front, and instead focusing on how to maximize the team’s ability to deliver quickly, to respond to emerging requirements, and to adapt to evolving technologies and changes in market conditions.
Main features of Scrum:
 a living backlog of prioritized work to be done
 completion of a fixed set of backlog items in a series of short iterations or sprints
 a brief daily meeting (“a scrum”) for explaining the progress, describing an upcoming work and possible obstacles
 a brief planning session in which the backlog items for the sprint will be defined
 a brief heartbeat retrospective when all team members reflect about the past sprint
Scrum is facilitated by a scrum master, whose primary job is to remove impediments to the ability of the team to deliver the sprint goal. The scrum master is not the leader of the team (as they are self-organizing) but acts as a productivity buffer between the team and any destabilizing influences.
This method encourages verbal communication across all team members and across all disciplines that are involved in the project.