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# XHandler
[](https://godoc.org/github.com/rs/xhandler) [](https://raw.githubusercontent.com/rs/xhandler/master/LICENSE) [](https://travis-ci.org/rs/xhandler) [](http://gocover.io/github.com/rs/xhandler)
XHandler is a bridge between [net/context](https://godoc.org/golang.org/x/net/context) and `http.Handler`.
It lets you enforce `net/context` in your handlers without sacrificing compatibility with existing `http.Handlers` nor imposing a specific router.
Thanks to `net/context` deadline management, `xhandler` is able to enforce a per request deadline and will cancel the context when the client closes the connection unexpectedly.
You may create your own `net/context` aware handler pretty much the same way as you would do with http.Handler.
Read more about xhandler on [Dailymotion engineering blog](http://engineering.dailymotion.com/our-way-to-go/).
## Installing
go get -u github.com/rs/xhandler
## Usage
```go
package main
import (
"log"
"net/http"
"time"
"github.com/rs/cors"
"github.com/rs/xhandler"
"golang.org/x/net/context"
)
type myMiddleware struct {
next xhandler.HandlerC
}
func (h myMiddleware) ServeHTTPC(ctx context.Context, w http.ResponseWriter, r *http.Request) {
ctx = context.WithValue(ctx, "test", "World")
h.next.ServeHTTPC(ctx, w, r)
}
func main() {
c := xhandler.Chain{}
// Add close notifier handler so context is cancelled when the client closes
// the connection
c.UseC(xhandler.CloseHandler)
// Add timeout handler
c.UseC(xhandler.TimeoutHandler(2 * time.Second))
// Middleware putting something in the context
c.UseC(func(next xhandler.HandlerC) xhandler.HandlerC {
return myMiddleware{next: next}
})
// Mix it with a non-context-aware middleware handler
c.Use(cors.Default().Handler)
// Final handler (using handlerFuncC), reading from the context
xh := xhandler.HandlerFuncC(func(ctx context.Context, w http.ResponseWriter, r *http.Request) {
value := ctx.Value("test").(string)
w.Write([]byte("Hello " + value))
})
// Bridge context aware handlers with http.Handler using xhandler.Handle()
http.Handle("/test", c.Handler(xh))
if err := http.ListenAndServe(":8080", nil); err != nil {
log.Fatal(err)
}
}
```
### Using xmux
Xhandler comes with an optional context aware [muxer](https://github.com/rs/xmux) forked from [httprouter](https://github.com/julienschmidt/httprouter):
```go
package main
import (
"fmt"
"log"
"net/http"
"time"
"github.com/rs/xhandler"
"github.com/rs/xmux"
"golang.org/x/net/context"
)
func main() {
c := xhandler.Chain{}
// Append a context-aware middleware handler
c.UseC(xhandler.CloseHandler)
// Another context-aware middleware handler
c.UseC(xhandler.TimeoutHandler(2 * time.Second))
mux := xmux.New()
// Use c.Handler to terminate the chain with your final handler
mux.GET("/welcome/:name", xhandler.HandlerFuncC(func(ctx context.Context, w http.ResponseWriter, req *http.Request) {
fmt.Fprintf(w, "Welcome %s!", xmux.Params(ctx).Get("name"))
}))
if err := http.ListenAndServe(":8080", c.Handler(mux)); err != nil {
log.Fatal(err)
}
}
```
See [xmux](https://github.com/rs/xmux) for more examples.
## Context Aware Middleware
Here is a list of `net/context` aware middleware handlers implementing `xhandler.HandlerC` interface.
Feel free to put up a PR linking your middleware if you have built one:
| Middleware | Author | Description |
| ---------- | ------ | ----------- |
| [xmux](https://github.com/rs/xmux) | [Olivier Poitrey](https://github.com/rs) | HTTP request muxer |
| [xlog](https://github.com/rs/xlog) | [Olivier Poitrey](https://github.com/rs) | HTTP handler logger |
| [xstats](https://github.com/rs/xstats) | [Olivier Poitrey](https://github.com/rs) | A generic client for service instrumentation |
| [xaccess](https://github.com/rs/xaccess) | [Olivier Poitrey](https://github.com/rs) | HTTP handler access logger with [xlog](https://github.com/rs/xlog) and [xstats](https://github.com/rs/xstats) |
| [cors](https://github.com/rs/cors) | [Olivier Poitrey](https://github.com/rs) | [Cross Origin Resource Sharing](http://www.w3.org/TR/cors/) (CORS) support |
## Licenses
All source code is licensed under the [MIT License](https://raw.github.com/rs/xhandler/master/LICENSE).
|
