diff --git a/Gemfile b/Gemfile
index 92afc60f..073f6d8a 100644
--- a/Gemfile
+++ b/Gemfile
@@ -17,6 +17,7 @@ gem 'i18n-js'
 gem 'ims-lti', '< 2.0.0'
 gem 'jbuilder'
 gem 'js-routes'
+gem 'json_schemer'
 gem 'kramdown'
 gem 'mimemagic'
 gem 'nokogiri'
diff --git a/Gemfile.lock b/Gemfile.lock
index d9309fff..f0efcde2 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -157,6 +157,8 @@ GEM
       multi_json
     domain_name (0.5.20190701)
       unf (>= 0.0.5, < 1.0.0)
+    ecma-re-validator (0.3.0)
+      regexp_parser (~> 2.0)
     erubi (1.10.0)
     eventmachine (1.2.7)
     excon (0.87.0)
@@ -194,6 +196,7 @@ GEM
     haml (5.2.2)
       temple (>= 0.8.0)
       tilt
+    hana (1.3.7)
     hashdiff (1.0.1)
     headless (2.3.1)
     highline (2.0.3)
@@ -222,6 +225,11 @@ GEM
     js-routes (2.1.1)
       railties (>= 4)
     json (2.3.1)
+    json_schemer (0.2.18)
+      ecma-re-validator (~> 0.3)
+      hana (~> 1.3)
+      regexp_parser (~> 2.0)
+      uri_template (~> 0.7)
     jwt (2.3.0)
     kaminari (1.2.1)
       activesupport (>= 4.1.0)
@@ -507,6 +515,7 @@ GEM
       unf_ext
     unf_ext (0.0.8)
     unicode-display_width (2.1.0)
+    uri_template (0.7.0)
     web-console (4.1.0)
       actionview (>= 6.0.0)
       activemodel (>= 6.0.0)
@@ -561,6 +570,7 @@ DEPENDENCIES
   ims-lti (< 2.0.0)
   jbuilder
   js-routes
+  json_schemer
   kramdown
   listen
   mimemagic
diff --git a/lib/runner/backend-output.schema.json b/lib/runner/backend-output.schema.json
new file mode 100644
index 00000000..a256846e
--- /dev/null
+++ b/lib/runner/backend-output.schema.json
@@ -0,0 +1,44 @@
+{
+  "$schema": "http://json-schema.org/schema#",
+  "title": "event",
+  "type": "object",
+  "oneOf": [
+    {
+      "properties": {
+        "type": {
+          "const": "exit",
+          "required": true
+        },
+        "data": {
+          "type": "integer",
+          "required": true,
+          "minimum": 0,
+          "maximum": 255
+        }
+      },
+      "additionalProperties": false
+    },
+    {
+      "properties": {
+        "type": {
+          "enum": [ "stdout", "stderr", "error" ],
+          "required": true
+        },
+        "data": {
+          "type": "string",
+          "required": true
+        }
+      },
+      "additionalProperties": false
+    },
+    {
+      "properties": {
+        "type": {
+          "enum": [ "start", "timeout" ],
+          "required": true
+        }
+      },
+      "additionalProperties": false
+    }
+  ]
+}
\ No newline at end of file
diff --git a/lib/runner.rb b/lib/runner/runner.rb
similarity index 74%
rename from lib/runner.rb
rename to lib/runner/runner.rb
index 4ef77a8a..aa5fa7bc 100644
--- a/lib/runner.rb
+++ b/lib/runner/runner.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'runner_connection'
-
 class Runner
   BASE_URL = CodeOcean::Config.new(:code_ocean).read[:container_management][:url]
   HEADERS = {"Content-Type" => "application/json"}
@@ -10,19 +8,19 @@ class Runner
 
   def initialize(execution_environment, time_limit = nil)
     url = "#{BASE_URL}/runners"
-    body = {execution_environment_id: execution_environment.id}
+    body = {executionEnvironmentId: execution_environment.id}
     if time_limit
-      body[:time_limit] = time_limit
+      body[:timeLimit] = time_limit
     end
     response = Faraday.post(url, body.to_json, HEADERS)
     response = parse response
-    @id = response[:id]
+    @id = response[:runnerId]
   end
 
   def copy_files(files)
     url = runner_url + "/files"
-    body = { files: files.map{ |filename, content| { filename: filename, content: content } } }
-    Faraday.post(url, body.to_json, HEADERS)
+    body = { files: files.map { |filename, content| { filepath: filename, content: content } } }
+    Faraday.patch(url, body.to_json, HEADERS)
   end
 
   def copy_submission_files(submission)
@@ -42,7 +40,7 @@ class Runner
 
   def execute_interactively(command)
     starting_time = Time.now
-    websocket_url = execute_command(command)[:websocket_url]
+    websocket_url = execute_command(command)[:websocketUrl]
     EventMachine.run do
       socket = RunnerConnection.new(websocket_url)
       yield(self, socket) if block_given?
@@ -55,7 +53,9 @@ class Runner
   end
 
   def status
-    parse(Faraday.get(runner_url))[:status].to_sym
+    # parse(Faraday.get(runner_url))[:status].to_sym
+    # TODO return actual state retrieved via websocket
+    :timeouted
   end
 
   private
diff --git a/lib/runner_connection.rb b/lib/runner/runner_connection.rb
similarity index 84%
rename from lib/runner_connection.rb
rename to lib/runner/runner_connection.rb
index 25008d66..415c282b 100644
--- a/lib/runner_connection.rb
+++ b/lib/runner/runner_connection.rb
@@ -1,7 +1,9 @@
 require 'faye/websocket/client'
+require 'json_schemer'
 
 class RunnerConnection
   EVENTS = %i[start output exit stdout stderr].freeze
+  BACKEND_OUTPUT_SCHEMA = JSONSchemer.schema(JSON.parse(File.read("lib/runner/backend-output.schema.json")))
 
   def initialize(url)
     @socket = Faye::WebSocket::Client.new(url, [], ping: 5)
@@ -36,7 +38,11 @@ class RunnerConnection
   end
 
   def on_message(event)
+    return unless BACKEND_OUTPUT_SCHEMA.valid?(JSON.parse(event.data))
+
     event = decode(event.data)
+
+    # TODO handle other events like timeout
     case event[:type].to_sym
     when :exit_code
       @exit_code = event[:data]