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Kaph writer

Simple facade for working with node.js http.ServerResponse inspired by Tornado.


Kaph writer just provides facade object for "brain-free" work with HTTP responses.

var http = require('http');
var kaphWriter = require('../kaph/chain/writer').Writer;

http.createServer(function(request, response) {
    var writer = new kaphWriter(request, response);
    writer.end('It\'s works');

Kaph writer constructor takes two arguments: request and response. Instance of Kaph writer provides several methods (they will be described below): setStatus, setHeader, write, end and redirect.

setStatus and setHeader

setStatus Sets response status code and takes one Number argument - code. By default, response status code is 200.


Response status code will be setted if match any of node.js http.STATUS_CODES. Otherwise, it will not be setted.

setHeader sets one response header. Takes two arguments: header's name and value. Non-String values will be converted by their toString method. undefined will be converted to empty String.

writer.setHeader('Big-Date', new Date());

By default in writer object already setted header Content-Type with value text/html; charset=UTF-8. Of course you can change it to any what you want. If given value is "unsafe", setHeader throws exception.

setStatus and setHeader methods doesn't write anything to http.ServerResponse.

write and end methods

Both methods are very similar to node.js http.ServerResponse methods, dut do for you some boring stuff. First, write and end checks if headers that setted by setHeader method not written yet, they write these headers to response.


write writes a chunk of the response body and takes two arguments: data and optional encoding. By default encoding is utf8. data handles by following rules:

  • Buffer and String values leaves untouched.
  • All values except undefined will be converted to String
  • undefined values will be silently discarded and nothing will be writed to response include headers.

end method also takes two arguments, but both these are optional. This method always ends response. data handles by rules similar to write method with one exception: undefined data also ends response.

If headers not written yet (ie write method never called), end method with non undefined data do something more:

  • If you not set "ETag" header by setHeader method end do it for you with sha1 hash of data.
  • If request has "If-None-Match" header, after calculating "ETag" end will compare these headers, and if they match - sends 304 (Not modified) response to client.
  • If "If-None-Match" and "ETag" not equal (or request hasn't "If-None-Match" header), end calculates "Content-Length" of data and set both response headers.


This method redirects client to given location. redirect takes two arguments: redirect URL and optional permanent flag.


With permanent flag, redirect send client status 301 instead of 302. You can't redirect after after headers have been written.

Usage in Kaph chain

This module provides operation to use with kaph. Usage is similar to that described above. With one difference - operation creates a new object writer inside kaph handler.

var http = require('http');
var HttpHandler = require('kaph/http').Handler;
var kaphWriter = require('kaph/chain/writer');

Op = {
    GET: function() {
        this.writer.end('It\'s works');

var chain = [kaphWriter.Op, Op];

http.createServer(function(request, response) {
    (new HttpHandler(request, response, chain)).next();