Software Design Patterns

Software Design Patterns are commonly used on object-oriented software development, they are previously defined methods to design and code programs, used commonly by experts and corporations that benefit from structured and unified ways to develop and execute. They serve as a common framework for developers and promote good coding practices.

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They were not developed intentionally, they were instead created by trial and error and the prevalent ones are the ones that, by natural selection, were proven to be the best ones.
The Gang of Four, are the ones that wrote a book and set the SDP principles down, the book is called "Design Patterns - Elements of Reusable Object-Oriented Software". The two main principles are:

• Program to an interface, not an implementation: Basically programming the classes in order for them to be implementable by other software, resuable and act as pieces of a bigger puzzle.
• Favor composition over inheritance: Classes should implement other classes to complete their functionality, rather than inheriting from them.

There are a lot of desing patterns and not one is always the "correct" one, nonetheless, four main pattern types are defined:

• Creational: Create objects on the go as they are being used.
• Structural: The composition of objects is of most importance, mix and match to obtain new functionality.
• Behavioral: Communication between objects is prioritized.
• J2EE: Presentation layer.

Source: https://www.tutorialspoint.com/design_pattern/design_pattern_overview.htm

Software Requirements

In order to define what a piece of software can do, you have to define clearly the functions and requirements that it must contain for the customer to be satisfied and your team to know what to do and how.

The goal is to arrive at a Software Requirements Specification (SRS) Document, a spec sheet that details what the software can do.

Photo by Nathanael Coyne on Flickr. CC BY-NC-ND

Requirement Engineering is a discipline that aims towards understanding client's requirements and translating them into technical and detailed specifications for the developers, it consists of four basic steps:

1. Feasibility Study: Knowing if what the client wants is possible, taking into account technical, economical, and organizational aspects. This stage outputs the feasibility study report.
2. Requirement Gathering: Getting the expectations of what the software should do from the client and end-users. Requirements must be clear, correct, consistent, coherent, modifiable, verifiable, unambiguous, traceable, and from a credible source.
3. Software Requirement Specification: After collecting information from all the people involved, an engineer creates the SRS, where the client's specifications are expressed in natural language, and all the technical aspects of the project are detailed in order for it to be useful for the development team, including pseudo code and GUI sketches.
4. Software Requirement Validation: Between the developer and client, the specifications are reviewed to verify that they are correct, within scope, and achievable.
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REQUIREMENT ELICITATION

It is an organized process to gather requirements for the software, it has four steps.

First the developer gets the requirements from the client, then they are prioritized and categorized, next they are reviewed with the stakeholders to remove any ambiguity or doubts about the requirements, finally, they are documented correctly for the next phases of development.

One or more of these methods can be used in the elicitation phases, each one with its ups and downs:

• Interviews
• Surveys
• Questionnaires
• Brainstorming
• Prototyping
• Observation

Hope y'all learned something from this :)

Sources:

Tutorialspoint: Software Requirements