2015 Terminology - SDLC

System Development Life Cycle (SDLC) is commonly known as the fundamental concept of building information system. It is composed of multiple phrases including Design, Coding, Testing, and Delivery phrase.

In a typical software development cycle, Software Engineering, is also known as programmer, following the four phrases to deliver good quality and user satisfied system.


Design phrase is to understand the purpose and usage of the information system. System Analyst is, usually an experienced programmer who familiar with the type of information and suitable technology, participate in this phrase to write system functions, and system design document. System functions should be discussed with the system user to meet user expectation. For example, If user expect to build a mobile application to display products, to add selected product into shopping cart, submit order from the shopping cart, and create email showing the order information and send to the customer. These expectation is considered as user expectation or as system functional requirements, and is written in a document called Functional Specification.

On the other aspect, the System Analyst select and decide the most suitable type of technology to build the information system. The consideration might be the type of Mobile Operating System (mobile OS) such as Apple's iOS, Google's Android, Microsoft's Windows Phone, Blackberry's BlackBerry, Mozilla's Firefox OS, Jolla's Sailfish, Tizen Association's Tizen, and Canonical Ltd.'s Ubuntu's Touch OS. Other concerns might be but not limited to security, customer information protection, user access control, capacity and server storage, system architecture, and third party library. These technical information is written in a document called Design (Technical) Specification.

It is believed that the Functional Specification and Design Specification is originated from the following standard.

The Military Standard set MIL-STD 490/483 recognized this newer approach (top-down approach) by specifying a system requirements document, a "design-to" requirements document that is created in response to the system requirements, and then "code-to" requirements document for each software module in the design. [1]

Coding phrase is the phrase that programmer write programming language to develop functionality base on the functional requirements.

Testing phrase is normally divided into two parts. One is named White Box Testing, in which programmer know the system logic embed in the code and test the system input and output, to identify the flaw (a.k.a. bug) in the programming logic. Unit Testing is a common practice of White Box Testing, that test a fragment of logic, and ensure the quality of the logic of an information system.

Another testing is named Black Box Testing, in which user know the system functionalities without knowing the logic, and test the system to identify the functions that meet the user requirements. Sometimes, user may take advantage of this phrase to rethink the functionalities is helpful to the business process or not. Hence, this is the phrase that user often raise change request of system functions before system delivery.

The last phrase of SDLC is the Delivery phrase, System Analyst arranges the pre-delivery and post-delivery activities in addition to the software deployment onto the server and software publication to the user.

There are various commonly used methodologies of SDLC such as Waterfall, Rapid Prototype, Agile, and Iterative development model.

Please continue to read other posts for other SDLC models.

Reference:

1. Bell, Thomas E., and T. A. Thayer. Software requirements: Are they really a problem? Proceedings of the 2nd international conference on Software engineering. IEEE Computer Society Press, 1976.