常见的默认值
Sails有绑定一组默认的常用的HTTP中间件供你使用。当然你可以禁用、重写或者追加新的内容，但是对于在产品或者开发模式下大部分的app的预安装的栈是完全可以接受的。下面是一组标准的HTTP中间件函数，有序地绑定到Sails中，当每次有HTTP收到的时候便会执行：
| HTTP Middleware Key | Purpose |
|---|---|
| startRequestTimer | 当请求开始的时候在内存中分配一个变量保存时间戳。这个可以被你的app访问到并被用于提供关于慢请求的诊断信息。 |
| cookieParser * | Parses the cookie header into a clean object for use in subsequent middleware and your application code. |
| session * | Sets up a unique session object using your session configuration. |
| bodyParser | Parses parameters and binary upstreams (for streaming file uploads) from the HTTP request body using Skipper. |
| compress | Compresses response data using gzip/deflate. See compression for details. |
| methodOverride | Provides faux HTTP method support, letting you use HTTP verbs such as PUT or DELETE in places where the client doesn't support it (e.g. legacy versions of Internet Explorer.) If a request has a _method parameter set to "PUT", the request will be routed as if it was a proper PUT request. See Connect's methodOverride docs for more information if you need it. |
| poweredBy | Attaches an X-Powered-By header to outgoing responses. |
| $custom | Provides backwards compatibility for a configuration option from Sails v0.9.x. Since Sails v0.10 offers much more configuration flexibility for HTTP middleware, as long as you are not using sails.config.express.customMiddleware, you can confidently remove this item from the list. |
| router * | This is where the bulk of your app logic gets applied to any given request. In addition to running "before" handlers in hooks (e.g. csrf token enforcement) and some internal Sails logic, this routes requests using your app's explicit routes (in sails.config.routes) and/or route blueprints. |
| www * | Serves static files- usually images, stylesheets, scripts- in your app's "public" folder (configured in sails.config.paths, conventionally .tmp/public/) using Connect's static middleware. |
| favicon | Serves the browser favicon for your app if one is provided as /assets/favicon.ico. |
| 404 * | Handles requests which do not match any routes - triggers res.notFound() |
| 500 * | Handles requests which trigger an internal error (i.e. call Express's next(err)) - triggers res.serverError() |