added sixpack to server side

services/web/app/coffee/infrastructure/Sixpack.coffee

@@ -0,0 +1,99 @@
+settings = require("settings-sharelatex")
+request = require("request")
+logger = require("logger-sharelatex")
+
+generate_client_id = ->
+	# from http://stackoverflow.com/questions/105034
+	'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace /[xy]/g, (c) ->
+		r = Math.random() * 16 | 0
+		v = if c == 'x' then r else r & 0x3 | 0x8
+		v.toString 16
+
+_request_uri = (endpoint, params) ->
+	query_string = []
+	e = encodeURIComponent
+	for key of params
+		if params.hasOwnProperty(key)
+			vals = params[key]
+			if Object::toString.call(vals) != '[object Array]'
+				vals = [ vals ]
+			i = 0
+			while i < vals.length
+				query_string.push e(key) + '=' + e(vals[i])
+				i += 1
+	if query_string.length
+		endpoint += '?' + query_string.join('&')
+	endpoint
+
+_request = (uri, params, callback)->
+	opts =
+		uri:_request_uri(uri, params)
+		json:true
+		timeout:1000
+	request.get opts, (err, res, body)->
+		callback err, body
+
+module.exports = sixpack =
+
+	client: (user_id)->
+		client = new sixpack.Session(user_id, settings.apis.sixpack.url)
+		return client
+
+	Session : (client_id, base_url, ip_address, user_agent) ->
+
+		@client_id = client_id or sixpack.generate_client_id()
+		@base_url = base_url or sixpack.base_url
+
+		participate: (experiment_name, alternatives, force, callback) =>
+			if typeof force == 'function'
+				callback = force
+				force = null
+			if !/^[a-z0-9][a-z0-9\-_ ]*$/.test(experiment_name)
+				return callback(new Error('Bad experiment_name'))
+			if alternatives.length < 2
+				return callback(new Error('Must specify at least 2 alternatives'))
+			i = 0
+			while i < alternatives.length
+				if !/^[a-z0-9][a-z0-9\-_ ]*$/.test(alternatives[i])
+					return callback(new Error('Bad alternative name: ' + alternatives[i]))
+				i += 1
+			params = 
+				client_id: @client_id
+				experiment: experiment_name
+				alternatives: alternatives
+
+			if force != null and _in_array(alternatives, force)
+				return callback(null,
+					'status': 'ok'
+					'alternative': 'name': force
+					'experiment':
+						'version': 0
+						'name': experiment_name
+					'client_id': @client_id)
+
+			_request @base_url + '/participate', params, (err, res) ->
+				if err?
+					res =
+						status: 'failed'
+						error: err
+						alternative: name: alternatives[0]
+				callback null, res
+
+		convert: (experiment_name, callback)=>
+			if !/^[a-z0-9][a-z0-9\-_ ]*$/.test(experiment_name)
+				return callback(new Error('Bad experiment_name'))
+			params = 
+				client_id: @client_id
+				experiment: experiment_name
+			if @ip_address
+				params.ip_address = @ip_address
+			if @user_agent
+				params.user_agent = @user_agent
+			_request @base_url + '/convert', params, (err, res) ->
+				if err?
+					res =
+						status: 'failed'
+						error: err
+				callback null, res
+
+

services/web/config/settings.defaults.coffee

@@ -104,6 +104,8 @@ module.exports =
 			url: "http://localhost:3026"
 		contacts:
 			url: "http://localhost:3036"
+		sixpack:
+			url: ""
 			
 	templates:
 		user_id: process.env.TEMPLATES_USER_ID or "5395eb7aad1f29a88756c7f2"

services/web/package.json

@@ -47,6 +47,7 @@
     "sanitizer": "0.1.1",
     "session.socket.io": "0.1.4",
     "settings-sharelatex": "git+https://github.com/sharelatex/settings-sharelatex.git#v1.0.0",
+    "sixpack-client": "^1.0.0",
     "socket.io": "0.9.16",
     "translations-sharelatex": "git+https://github.com/sharelatex/translations-sharelatex.git#master",
     "underscore": "1.6.0",