add Cache304 as an alternative to the server-side kataras/iris/cache middleware - it can perform better with less server overheat but it comes with a cost of 304 instead of 200 so custom clients must make that check

Former-commit-id: b0ba68c528c870fe060e2825c35689771a1d3680

_examples/README.md

@@ -382,6 +382,7 @@ The `httptest` package is your way for end-to-end HTTP testing, it uses the http
 iris cache library lives on its own [package](https://github.com/kataras/iris/tree/master/cache).
 
 - [Simple](cache/simple/main.go)
+- [Client-Side (304)](cache/client-side/main.go) - part of the iris context core
 
 > You're free to use your own favourite caching package if you'd like so.
 

_examples/cache/client-side/main.go

@@ -6,22 +6,34 @@
 package main
 
 import (
-	"fmt"
 	"time"
 
 	"github.com/kataras/iris"
 )
 
-var modtime = time.Now()
-
-func greet(ctx iris.Context) {
-	ctx.Header("X-Custom", "my  custom header")
-	response := fmt.Sprintf("Hello World! %s", time.Now())
-	ctx.WriteWithExpiration([]byte(response), modtime)
-}
+const refreshEvery = 10 * time.Second
 
 func main() {
 	app := iris.New()
+	app.Use(iris.Cache304(refreshEvery))
+	// same as:
+	// app.Use(func(ctx iris.Context) {
+	// 	now := time.Now()
+	// 	if modified, err := ctx.CheckIfModifiedSince(now.Add(-refresh)); !modified && err == nil {
+	// 		ctx.WriteNotModified()
+	// 		return
+	// 	}
+
+	// 	ctx.SetLastModified(now)
+
+	// 	ctx.Next()
+	// })
+
 	app.Get("/", greet)
 	app.Run(iris.Addr(":8080"))
 }
+
+func greet(ctx iris.Context) {
+	ctx.Header("X-Custom", "my  custom header")
+	ctx.Writef("Hello World! %s", time.Now())
+}

_examples/cache/simple/main.go

@@ -73,3 +73,8 @@ func writeMarkdown(ctx iris.Context) {
 
 	ctx.Markdown(markdownContents)
 }
+
+/* Note that `StaticWeb` does use the browser's disk caching by-default
+therefore, register the cache handler AFTER any StaticWeb calls,
+for a faster solution that server doesn't need to keep track of the response
+navigate to https://github.com/kataras/iris/blob/master/_examples/cache/client-side/main.go */