** Implement to define BedSheet middleware.
**
** HTTP requests are funnelled through a stack of middleware instances until they reach a terminator.
** The default BedSheet terminator returns a 404 error.
**
** Middleware may perform processing before and / or after passing the request down the pipeline to
** other middleware instances. Use middleware to address cross cutting concerns such as
** authentication and authorisation. See the FantomFactory article
** [Basic HTTP Authentication With BedSheet]`article:basic-http-authentication-with-bedSheet` for examples.
**
** Because middleware effectively wrap other middleware instances and each can terminate the
** pipeline prematurely, the ordering of middleware is extremely important.
**
** 'Route' instances are processed in the 'Routes' middleware. So generally you would explicitly
** contribute your own middleware to be *before* or *after* this.
**
** IoC Configuration
** =================
** Instances of 'Middleware' should be contributed to the 'MiddlewarePipeline' service.
**
** For example, in your 'AppModule' class:
**
** pre>
** syntax: fantom
** @Contribute { serviceType=MiddlewarePipeline# }
** Void contributeMiddleware(Configuration config) {
** config.set("MyMiddleware", config.build(MyMiddleware#)).before("afBedSheet.routes")
** }
** <pre
**
** To list all middleware instances used by BedSheet (on startup), add the following to your
** IoC Module:
**
** pre>
** Void onRegistryStartup(Configuration config) {
** scope := config.scope
** config.set("logMiddleware", |->| {
** scope.serviceByType(MiddlewarePipeline#)->logMiddleware
** })
** }
** <pre
// Used by Duvet
const mixin Middleware {
** Call 'pipeline.service' to allow other Middleware to further process the request:
**
** pre>
** syntax: fantom
** const class MyMiddleware : Middleware {
** override Void service(MiddlewarePipeline pipeline) {
** ...
** ...
** // pass the request to other middleware for processing
** pipeline.service
** ...
** ...
** }
** }
** <pre
abstract Void service(MiddlewarePipeline pipeline)
}
