add serve http/2 without tls example

_examples/http-server/h2c/main.go

@@ -0,0 +1,52 @@
+package main
+
+import (
+	"net/http"
+
+	"github.com/kataras/iris/v12"
+
+	"golang.org/x/net/http2"
+)
+
+/*
+	Serve HTTP/2 without TLS and keep support for HTTP/1.1
+*/
+
+// $ go get golang.org/x/net/http2
+// # Take a look at the golang.org/x/net/http2/h2c package as well,
+// # you may want to use it.
+// $ go run main.go
+// $ brew install curl-openssl
+// # Add curl-openssl to the front of your path.
+// Test with the following commands:
+// $ curl -v --http2 http://localhost:8080
+// $ curl -v --http1.1 http://localhost:8080
+func main() {
+	// Initialize Iris Application.
+	app := iris.New()
+
+	// Build the API.
+	app.Any("/", index)
+
+	// Finally, listen and serve on port 8080 using h2c.
+	app.Run(iris.Raw(func() error {
+		host := app.NewHost(&http.Server{
+			Addr: ":8080",
+		})
+
+		err := http2.ConfigureServer(host.Server, &http2.Server{
+			MaxConcurrentStreams:         250,
+			PermitProhibitedCipherSuites: true,
+		})
+
+		if err != nil {
+			return err
+		}
+
+		return host.ListenAndServe()
+	}))
+}
+
+func index(ctx iris.Context) {
+	ctx.WriteString("Hello, World!\n")
+}