add comments for middleware packages, fix typo error

@@ -221,7 +221,7 @@ func Run() {
 
 	middleware.VERSION = VERSION
 	middleware.AppName = AppName
-	middleware.RegisterErrorHander()
+	middleware.RegisterErrorHandler()
 
 	if EnableAdmin {
 		go BeeAdminApp.Run()

@@ -61,6 +61,7 @@ var tpl = `
 </html>
 `
 
+// render default application error page with error and stack string.
 func ShowErr(err interface{}, rw http.ResponseWriter, r *http.Request, Stack string) {
 	t, _ := template.New("beegoerrortemp").Parse(tpl)
 	data := make(map[string]string)
@@ -175,13 +176,14 @@ var errtpl = `
 </html>
 `
 
+// map of http handlers for each error string.
 var ErrorMaps map[string]http.HandlerFunc
 
 func init() {
 	ErrorMaps = make(map[string]http.HandlerFunc)
 }
 
-//404
+// show 404 notfound error.
 func NotFound(rw http.ResponseWriter, r *http.Request) {
 	t, _ := template.New("beegoerrortemp").Parse(errtpl)
 	data := make(map[string]interface{})
@@ -199,7 +201,7 @@ func NotFound(rw http.ResponseWriter, r *http.Request) {
 	t.Execute(rw, data)
 }
 
-//401
+// show 401 unauthorized error.
 func Unauthorized(rw http.ResponseWriter, r *http.Request) {
 	t, _ := template.New("beegoerrortemp").Parse(errtpl)
 	data := make(map[string]interface{})
@@ -215,7 +217,7 @@ func Unauthorized(rw http.ResponseWriter, r *http.Request) {
 	t.Execute(rw, data)
 }
 
-//403
+// show 403 forbidden error.
 func Forbidden(rw http.ResponseWriter, r *http.Request) {
 	t, _ := template.New("beegoerrortemp").Parse(errtpl)
 	data := make(map[string]interface{})
@@ -232,7 +234,7 @@ func Forbidden(rw http.ResponseWriter, r *http.Request) {
 	t.Execute(rw, data)
 }
 
-//503
+// show 503 service unavailable error.
 func ServiceUnavailable(rw http.ResponseWriter, r *http.Request) {
 	t, _ := template.New("beegoerrortemp").Parse(errtpl)
 	data := make(map[string]interface{})
@@ -248,7 +250,7 @@ func ServiceUnavailable(rw http.ResponseWriter, r *http.Request) {
 	t.Execute(rw, data)
 }
 
-//500
+// show 500 internal server error.
 func InternalServerError(rw http.ResponseWriter, r *http.Request) {
 	t, _ := template.New("beegoerrortemp").Parse(errtpl)
 	data := make(map[string]interface{})
@@ -262,15 +264,18 @@ func InternalServerError(rw http.ResponseWriter, r *http.Request) {
 	t.Execute(rw, data)
 }
 
+// show 500 internal error with simple text string.
 func SimpleServerError(rw http.ResponseWriter, r *http.Request) {
 	http.Error(rw, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
 }
 
+// add http handler for given error string.
 func Errorhandler(err string, h http.HandlerFunc) {
 	ErrorMaps[err] = h
 }
 
-func RegisterErrorHander() {
+// register default error http handlers, 404,401,403,500 and 503.
+func RegisterErrorHandler() {
 	if _, ok := ErrorMaps["404"]; !ok {
 		ErrorMaps["404"] = NotFound
 	}
@@ -292,6 +297,8 @@ func RegisterErrorHander() {
 	}
 }
 
+// show error string as simple text message.
+// if error string is empty, show 500 error as default.
 func Exception(errcode string, w http.ResponseWriter, r *http.Request, msg string) {
 	if h, ok := ErrorMaps[errcode]; ok {
 		isint, err := strconv.Atoi(errcode)

@@ -2,16 +2,19 @@ package middleware
 
 import "fmt"
 
+// http exceptions
 type HTTPException struct {
 	StatusCode  int // http status code 4xx, 5xx
 	Description string
 }
 
+// return http exception error string, e.g. "400 Bad Request".
 func (e *HTTPException) Error() string {
-	// return `status description`, e.g. `400 Bad Request`
 	return fmt.Sprintf("%d %s", e.StatusCode, e.Description)
 }
 
+// map of http exceptions for each http status code int.
+// defined 400,401,403,404,405,500,502,503 and 504 default.
 var HTTPExceptionMaps map[int]HTTPException
 
 func init() {