gistfile1.js

middleware capable (not true so far :) of gzipping Buffers:
=======================================
function dir(x){var sys=require('sys');sys.debug(sys.inspect(x));}
exports.Compress = function(nextApp){
	return function(request){
		var encoding = 'gzip';
		if ((request.headers['accept-encoding']||'').indexOf(encoding) >= 0) {
//dir('gzipping');
			// so far only node.js provides compression module
			var Gzip = require('compress').Gzip;
			if (true && Gzip) {
				return require('promise').when(nextApp(request), function(response){
					var zipper = new Gzip;
					zipper.init();
					var data = response.body;
					response.body = {
						encoding: 'binary',
						forEach: function(write){
							var r = data.forEach(function(chunk){
								//if (chunk instanceof Buffer) chunk = chunk.toString('binary', 0, chunk.length);
								return write(zipper.deflate(chunk, 'binary'));
							});
							write(zipper.end());
							return r;
						}
					};
					/*response.body = {
						encoding: 'binary',
						forEach: function(write){
							var Buffer = require('buffer').Buffer;
dir('begin');
							var r = data.forEach(function(chunk){
								return require('promise').when(chunk, function(chunk){
									//if (chunk instanceof Buffer) chunk = chunk.toString('binary', 0, chunk.length);
									return write(zipper.deflate(chunk, 'binary'));
								});
							});
dir('end');
							write(zipper.end());
dir('end1');
							return r;
						}
					};*/
					/*response.body = {
						encoding: 'binary',
						forEach: function(write){
							return data.forEach(function(chunk){
								write(chunk.toString('binary'));
							});
						}
					};*/
					//response.headers['content-encoding'] = encoding;
//dir('gzipped');
					return response;
				});
			}
		}
		return nextApp(request);
	};
};



separate middleware version:
==========================
/**
 * JSGI app that GZIPs the response
 */
exports.Compress = function(nextApp){
	return function(request){
		var encoding = 'gzip';
		if ((request.headers['accept-encoding']||'').indexOf(encoding) >= 0) {
			// so far only node.js provides compression module
			var Gzip = require('compress').Gzip;
			if (true && Gzip) {
				return require('promise').when(nextApp(request), function(response){
					var zipper = new Gzip;
					zipper.init();
					var data = response.body;
					response.body = {
						encoding: 'binary',
						forEach: function(write){
							data.forEach(function(chunk){
								write(zipper.deflate(chunk, 'binary'));
							});
							write(zipper.end());
						}
					};
					response.headers['content-encoding'] = encoding;
					return response;
				});
			}
		}
		return nextApp(request);
	};
};



jsgi/media inline version:
==========================
			// compress the body
			var encoding = 'gzip';
			if ((request.headers['accept-encoding']||'').indexOf(encoding) >= 0) {
				// so far only node.js provides compression module
				var Gzip = require('compress').Gzip;
				if (Gzip) {
					var zipper = new Gzip;
					zipper.init();
					var data = response.body;
					response.body = {
						encoding: 'binary',
						forEach: function(write){
							data.forEach(function(chunk){
								write(zipper.deflate(chunk, 'binary'));
							});
							write(zipper.end());
						}
					};
					response.headers['content-encoding'] = encoding;
				}
			}