Systems Development Lifecycle (SDLC): The Waterfall model

The Waterfall model is a traditional lifecycle that views a software project from beginning to end. Each step is well defined and generally has an end and start date.

1. Requirements Definition
2. Analysis
3. Design
4. Implementation
5. Testing

This model has several shortcomings. For instance, the first stage deals with defining requirements, but often, new requirements will surface during another stage of development. The Waterfall model does not make allowances for such 'discoveries' during a project.

For this reason, many iterative models have emerged - iterative, meaning repeating. An iterative model can be described as a servies of mini waterfalls that are repeated until the project is complete. Generally, each iteration will achieve a small area of the desired functionality.

Parts of an ASP.NET Web Application

Web Forms or .aspx pages
Web Forms and .aspx pages provide the user interface for the Web application.

Code-behind pages
Code-behind pages are associated with Web Forms and contain the server-side code for the Web Form.

Configuration Files
Configuration files are XML files that define the default settings for the Web application and the Web server. Every Web application has one Web.config configuration file.

Global.asax File
Global.asax files contain the needed code for responding to application-level events that are raised by ASP.NET.

XML Web service links
XML Web srevice links allow the Web application to send and recieve data from an XML Web service.

Database connectivity
Database connectivity allows the Web application to transfer data to and from database sources.

Caching
Caching allow the Web application to return Web Forms and data more quickly after the first request.