add "write_headers_string" to RESPONSE_BUFFER

examples/hello_routed_world/src/hello_routed_world.e

@@ -64,7 +64,7 @@ feature -- Execution
 			n := 3
 			h.put_refresh (l_url, 5, 200)
 			res.set_status_code (200)
-			res.write_string (h.string)
+			res.write_headers_string (h.string)
 			from
 				create e
 			until

library/server/ewsgi/specification/response/ewsgi_response_buffer.e

@@ -97,6 +97,16 @@ feature -- Output operation
 
 feature -- Header output operation
 
+	write_headers_string (a_headers: STRING)
+		require
+			status_set: status_is_set
+			header_not_committed: not header_committed
+		deferred
+		ensure
+			status_set: status_is_set
+			header_committed: header_committed
+		end
+
 	write_header (a_status_code: INTEGER; a_headers: detachable ARRAY [TUPLE [key: STRING; value: STRING]])
 			-- Send headers with status `a_status', and headers from `a_headers'
 		require

library/server/ewsgi/src/extra/response_as_result/ewsgi_response.e

@@ -31,7 +31,7 @@ feature {EWSGI_RESPONSE_APPLICATION} -- Response status
 	transmit_to (res: EWSGI_RESPONSE_BUFFER)
 		do
                 res.set_status_code (status)
-                res.write_string (headers)
+                res.write_headers_string (headers)
                 from
                     read_block
                     res.write_string (last_block)

library/server/ewsgi/src/response/ewsgi_response_buffer.e

@@ -115,6 +115,18 @@ feature -- Output operation
 
 feature -- Header output operation		
 
+	write_headers_string (a_headers: STRING)
+		require
+			status_set: status_is_set
+			header_not_committed: not header_committed
+		do
+			write (a_headers)
+			header_committed := True
+		ensure
+			status_set: status_is_set
+			header_committed: header_committed
+		end
+
 	write_header (a_status_code: INTEGER; a_headers: detachable ARRAY [TUPLE [key: STRING; value: STRING]])
 			-- Send headers with status `a_status', and headers from `a_headers'
 		require
@@ -138,8 +150,7 @@ feature -- Header output operation
 					i := i + 1
 				end
 			end
-			write (h.string)
+			write_headers_string (h.string)
-			header_committed := True
 		ensure
 			status_set: status_is_set
 			header_committed: header_committed