symfony快速应用程序开发 (RAD)

symfony快速应用程序开发 (RAD)

开发网页程序是一件单调乏味的，慢速的事情。 例如常规软件开发生存周期(like the one proposed by the Rational Unified Process, for instance)，要等到有完整的需求才能开始开发， 绘制大量的UML图， 产生了大量的正式文档之前准备阶段的文档（preliminary documentation？）。 这就是一般的开发步速，缺少通用性的程序语言（在能正式看到程序可以用之前不知道要多少次的建立，编译，重起）， 最主要的就是客户不会经常改变他们的主意。 (Programming web applications has long been a tedious and slow job. Following the usual software engineering life cycles (like the one proposed by the Rational Unified Process, for instance), the development of web applications could not start before a complete set of requirements was written, a lot of Unified Modeling Language (UML) diagrams were drawn, and tons of preliminary documentation were produced. This was due to the general speed of development, to the lack of versatility of programming languages (you had to build, compile, restart, and who knows what else before actually seeing your program run), and most of all, to the fact that clients were quite reasonable and didn't change their minds constantly.)

今天，商业节奏更快了，客户总是倾向于在制作项目中经常改变他们的需求。 当然， 他们期望开发组能接受他们的需求并且快速更改应用程序的架构。 幸运的是， 使用脚本语言就像Perl和PHP会更容易的去实现这些，例如快速应用程序开发（RAD）和敏捷程序开发。

尽快去建立一个工作原型以便客户可以审阅并且提出问题是一个好方法。如此周而复始，在较短的开发周期发布新的功能(releasing increasingly feature-rich versions in short development cycles)。

The consequences for the developer are numerous。 一个开发者不需要去想在未来如何实现一个新功能。 用最简单的方法去实现需要的功能。 这就是KISS原则的一个很好体现： Keep It Simple, Stupid.

当需求变化或者功能增加的时候， 有时需要重写代码。 这就叫做重构， 这经常发生在网页应用程序开发中。代码会更根据需要改变存放位置。把重复的地方合并到一个地方，这就是Don't Repeat Yourself (DRY)原则。

当程序改变后要去确保依旧能够运行， 这需要一系列的自动测试来完成。 如果写得好的话， 单元测试将是在重构代码后检查的一个好的方法。 一些开发方法学（development methodologies ）甚至于规定在编写代码前先写测试--这就使称之为测试驱动开发test-driven development (TDD)。

NOTE 关于敏捷开发还有其一些它原则和好习惯。 一个敏捷开发理论中最有效率的方法叫做极限开发语言（Extreme Programming）（简称XP），XP教材会教你如何去快速而有效的去开发一个程序。 A good starting place is the XP series books by Kent Beck (Addison-Wesley).

Symfony is the perfect tool for RAD. As a matter of fact, the framework was built by a web agency applying the RAD principle for its own projects. This means that learning to use symfony is not about learning a new language, but more about applying the right reflexes and the best judgment in order to build applications in a more effective way.

The symfony project website proposes a step-by-step tutorial illustrating the development of an application in an agile way. It is called askeet (http://www.symfony-project.com/askeet), and is recommended reading for those who want to learn more about agile development.