分类： 模式与架构

一个糟糕的的程序接口的设计不仅仅是对接口调用者的摧残，更是对整个系统估值的贬低以及对设计者的能力的贬低。

下午工作的时候，发现在现在的项目，很对接口设计都令人抓狂，在一些地方不仅仅是设计的不好，而是似乎没有经过设计。比如，在一个接口中，明明是只需要一个Device ID (int)列表就能达到目的，却要求传入一个完全的Device列表，调用者不得不构建一个个的Device对象，如果构建这些Device对象是通过web service的方式获取的话，那么会在性能上照成严重的拖累。

软件设计的最少知识原则(PLK)也是KISS原则(Keep It Simple and Stupid)的一种体现，它们都希望使用你设计的接口或者界面的用户，只希望通过最少的操作就能达到他们的目标。就我个人而言，是非常推崇这种设计的，正如那句广告，简约而不简单。 （更多…）

What are the criteria for a good REST-ful URI?

I assert:

• Short (as possible). This makes them easy to write down or spell or remember.
• Hackable ‘up the tree’. The user should be able to remove the leaf path and get an expected page back. e.g. http://example.com/cars/alfa-romeos/gt you could remove the gt bit and expect to get back all the alfa-romeos.
• Meaningful. Describes the resource. I should have a hint at the type of resource I am looking at (a blog post, or a conversation). Ideally I would have a clue about the actual content of the URI (e.g. a uri like uri-design-essay)
• Predictable. Human-guessable. If your URLs are meaningful they may also be predictable. If your users understand them and can predict what a url for a given resource is then may be able to go ‘straight there’ without having to find a hyperlink on a page. If your URIs are predictable, then your developers will argue less over what should be used for new resource types.
• Help visualize the site structure. This helps make them more ‘predictable’.
• Readable.
• Nouns, not verbs.
• Query args (everything after the ?) are used on querying/searching resources (exclusively). They contain data the affects the query.
• Consistent. If you use extensions, do not use .html in one location and .htm in another. Consistent patterns make URIs more predictable.
• Stateless.
• Return a representation (e.g. XML or json) based on the request headers, like Accept and Accept-Language rather than a change in the URI.
• Tied to a resource. Permanent. The URI will continue to work while the resource exists, and despite the resource potentially changing over time.
• Report canonical URIs. If you have two different URIs for the same resource, ensure you put the canonical URL in the response.
• Follows the digging-deeper-path-and-backspace convention. URI path can be used like a backspace.

Some of these criteria pull against each other. For example, how can I make a meaningful-yet-short uri? URI-design rightly remains an art not a science. （更多…）

J2EE学习者越来越多，J2EE本身技术不断在发展，涌现出各种概念，本文章试图从一种容易理解的角度对这些概念向初学者进行解释，以便掌握学习J2EE学习方向。
首先我们需要知道Java和J2EE是两个不同概念，Java不只是指一种语言，已经代表与微软不同的另外一个巨大阵营，所以Java有时是指一种软件系统的流派，当然目前主要是.NET和Java两大主流体系。 （更多…）