This workshop introduces to WebRTC and how you can utilize its open API to develop Rich Communication services in your web applications. It describes a general Java gateway to allow the translation of WebRTC to SIP, the protocol used internally in the majority of VoIP networks and how Groovy is used to empower the process. In the end of the workshop, the assistants will be able to develop and deploy a basic webpage and they will have the knowledge to customize the example and develop more complex features, adding audio, video or data to HTML5, iOS or Android applications.

1. Using Groovy to empower WebRTC
Network Systems
Antón R. Yuste
@antonmry

2. Agenda
●
What is (and isn't WebRTC)
●
Developing your own WebRTC service
●
Groovy & Network Systems
●
TADHack 2015

3. Once upon a time...

4. Forever

5. There was a time...
●
Where we use to see video by using plug-ins and
external software
●
Instant Messaging was delivered using the same
concepts and Voice = Telephony
●
Suddenly everything changed

6. WebRTC @ Glance
WebRTC offers real time
communication natively
from a web browser

7. WebRTC @ Glance
WebRTC capable
browser share, including
Mobile, Tablet and
desktop
61%

8. WebRTC @ Glance
WebRTC is a
“MediaEngine” with
javascript API
API

9. WebRTC @ Glance
WebRTC is a technology,
NOT a solution,
AND open source
projects too

10. So, what is WebRTC?
●
A built-in application program interface that enables
browser-to-browser applications for:
●
voice calling
●
video chat
●
peer to peer of any data
●
Media engine in the browser, accessed by JavaScript,
downloaded from web-server.
●
Collaborative W3C and IETF standardization

11. The WebRTC tree
IMS, LTE
WWW
VoIP

12. So, what is WebRTC - Technically Speaking?
PEER CONNECTION
(AUDIO, VIDEO, DATA)
WEB SERVER
(WEBRTC CONTROL)
GATEWAY
PEER CONNECTION
(AUDIO, VIDEO, DATA)
PEER CONNECTION
(AUDIO, VIDEO, DATA)
WEB SERVER
(WEBRTC CONTROL)

13. What isn't WebRTC - Technically Speaking?
●
No MTI coded media
●
No defined signaling mechanism
It's a Standard
Specification and an
opensource project

14. Signaling – The Two Approach
SIP over WebSockets JSON over WebSockets

15. Why JSON, XMPP, * and not SIP?
●
Much more easy
●
There are more developers
●
Language of the web
●
And it’s natively supported by browser
●
Drives more SIP into the network

16. WebRTC Browser Support: Desktop

17. WebRTC Regional Browser Support: Desktop

18. A new Sheriff in town
●
August 20, 2014. Microsoft published a blog post
publicly supporting the ORCT draft.

19. Browser support

20. WebRTC Browser Support: Mobile

21. Consideration
●
Lack of WebRTC Support:
●
SDK/library for Windows Phone and IOS devices
●
Hardware support for Mobile Phone
●
Software encoding & decoding will kill your battery
for VP8
●
New device will benefits from power processor
●
Snapdragon 800 4
●
nVidia Tegra 4

22. Where we are now?

23. Is WebRTC ready?
… and more!

24. Major WebRTC Standard APIs
Acquire audio/video
Communicate Media
Communicate Data
MediaStream/getUserMedia
RTCPeerConnection
RTCDataChannel

25. MediaStream
●
Represents a stream of audio/video (stream from
camera/mike)
●
Multiple Tracks
●
Use navigator.getUserMedia()

26. MediaStream
var constraints = {video: true};
function successCallback(stream) {
var video =
document.querySelector("video");
video.src =
window.URL.createObjectURL(stream);
}
function errorCallback(error) {
console.log("navigator.getUserMedia error:
", error);
}
navigator.getUserMedia(constraints,
successCallback, errorCallback);

27. RTCPeerConnection
●
Centre of WebRTC
Standard API.
●
Peer to Peer
Communication
●
Codec, Security,
bandwidth etc.

28. RTCPeerConnection
pc = new RTCPeerConnection(null);
pc.onaddstream = gotRemoteStream;
pc.addStream(localStream);
pc.createOffer(gotOffer);
function gotOffer(desc) {
pc.setLocalDescription(desc);
sendOffer(desc);
}
function gotAnswer(desc) {
pc.setRemoteDescription(desc);
}
function gotRemoteStream(e) {
attachMediaStream(remoteVideo, e.stream);
}

29. RTCDataChannel
●
Arbitrary Data
●
File
●
Text
●
Games
●
API Similar to WebSockets
●
Peer to Peer Data
●
Use SCTP

30. RTCDataChannel
var pc = new webkitRTCPeerConnection(servers,
{optional: [{RtpDataChannels: true}]});
pc.ondatachannel = function(event) {
receiveChannel = event.channel;
receiveChannel.onmessage = function(event){
document.querySelector("div#receive").innerHTML =
event.data;
};
};
sendChannel = pc.createDataChannel("sendDataChannel",
{reliable: false});
document.querySelector("button#send").onclick = function (){
var data = document.querySelector("textarea#send").value;
sendChannel.send(data);
};

31. WebRTC Signaling
HTML
App
Browser
HTML
App
Browser
Session Description
Protocol
Signaling? Signaling?
Media(RTCP/RTP)
Caller Callee
Session Description
Protocol

32. WebRTC Offer/Answer Model
HTML
App
Browser
HTML
App
Browser
How ? How ?
Caller Callee
offer answer

33. ICE/STUN
Caller Callee
media media
STUN

34. ICE/TURN
Caller Callee
media
STUN STUN
TURN TURN

35. The entire exchange in a complicated diagram

36. How to start using WebRTC API ?

37. Prerequisites
●
Java 7
●
Maven 3.2+
●
Git
●
Your favorite IDE
●
Chrome browser
●
Internet Connection

38. Practice
git clone https://github.com/antonmry/SpringIOWebRTCSampleApp.git
ant jetty:run

39. Follow the mantra…
●
Java is Groovy, Groovy is Java.
●
Flat learning curve for Java developers, start with
straight Java syntax then move on to a groovier syntax
as you feel comfortable.
●
Almost 98% Java code is Groovy code, meaning you
can in most changes rename *.java to *.groovy and it
will work.

40. Template Engine maps messages in both
directions between applications and network
JSON Template
Engine
SIP message
Application Network

41. Call
Flow
detail

42. Components and developer extension points

43. Template Engine configuration
Package
Criteria
Script
template
Script
template
Script
template
Template Library
Criteria
Criteria

44. The Console Window

45. Package configuration
Inbound
INVITE
request
criteria

46. Inbound INVITE Request Template
TemplateContext passed as an argument
Using Script Library method
Creating a future task executed on successful ME response

47. Script Library
Groovy method specified in Inbound INVITE request template script

48. Groovy tips and tricks
●
Use “def” to declare variables and make them local:
def b = "foo“.
●
Simplification of a getter method notation: def factory
= context.webFactory // instead of
context.getWebFactory()
●
Safe navigation operator (?.): def errorCode =
context.webMessage?.header?.error_code
●
Check for a null object: if
(context.webMessage?.payload?.sdp)

49. Groovy tips and tricks
●
Compile static @groovy.transform.CompileStatic (no
dynamic types, compiles better and faster)
●
Iterators
●
’as’ keyword
●
Closures
●
array and list operators * and *. – called ”spread” and
”spread-dot”
●
GPath – similar to xpath but runs on objects not xml

50. Groovy scripts troubleshooting
●
Add println statements and see output in the system
out, e.g.: println “from=" + from
●
Use log4j and see output in wsc.log file, e.g.
org.apache.log4j.Logger logger =
org.apache.log4j.Logger.getLogger(getClass())
logger.info(“groovy info: from=“ + from)
●
When an exception is thrown within a Groovy script, a
stack trace will be logged in the wsc.log file.

51. Groovy scripts troubleshooting

52. Groovy scripts troubleshooting
Caused by: groovy.lang.MissingPropertyException: No such property: sipReq for class: Script2
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.unwrap(ScriptBytecodeAdapter.java:50)
at org.codehaus.groovy.runtime.callsite.PogoGetPropertySite.getProperty(PogoGetPropertySite.java:49)
at
org.codehaus.groovy.runtime.callsite.AbstractCallSite.callGroovyObjectGetProperty(AbstractCallSite.java:231
)
at Script2.pkg_register_dir_FROM_APP_typ_request_verb_connect_netsvc_default(Script2.groovy:705)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:233)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1085)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:952)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:909)
at groovy.lang.Closure.call(Closure.java:411)
at org.codehaus.groovy.jsr223.GroovyScriptEngineImpl.callGlobal(GroovyScriptEngineImpl.java:411)
at org.codehaus.groovy.jsr223.GroovyScriptEngineImpl.callGlobal(GroovyScriptEngineImpl.java:405)
at org.codehaus.groovy.jsr223.GroovyScriptEngineImpl.invokeImpl(GroovyScriptEngineImpl.java:394)
...

53. Groovy scripts validation

54. Example SIP Request Variable
// Create REGISTER request
def from = getFromAddress(context)
def to = getToAddress(context)
def sipReq = context.sipFactory.createSipRequest("REGISTER",
from, to)
// Set request URI
sipReq.requestURI =
context.sipFactory.createSipAddress(Constants.PROXY_SIP_URI)
.URI
// Set contact user
if (from.URI?.user) {
sipReq.setContactUser(from.URI.user)
}
// Set sip.instance to allow container to use SIP Outbound
// for routing purposes as defined in RFC 5626
def sipInstance = ""<urn:uuid:" +
java.util.UUID.randomUUID() + ">""
sipReq.setSipContactParameter("+sip.instance", sipInstance)
sipReq.setSipContactParameter("reg-id", "1")
context.subSessionStore.put("sip.instance", sipInstance)
sipReq.send()

55. GRUUs
A GRUU (Globally Routable User-Agent URI) is a SIP URI which
has a few properties.
?

56. Example SIP Request Variable
sipReq.setHeader("Supported", "gruu")
// P-Charging-Vector example
def icidValue = context.uniqueId
def myIp =
java.net.InetAddress.localHost.hostAddress
sipReq.setHeader("P-Charging-Vector", "icid-
value=" + icidValue +
";icid-generated-at=" + myIp)

57. Protecting System Performance
by Removing SIP Messages
if (sipResponse.status < 200) {
// Ignore provisional responses
} else if (sipResponse.status < 300)
// Proceed with processing
}
{...
}

58. Removing a SIP Header in a
Message
sipReq.removeHeader("headername")

59. Conditionally Passing SIP Headers
in Messages
def myWebParameter =
context.webMessage?.header.?myParameter
if (myWebParameter) {
sipRequest.setHeader("MyHeader",
myWebParameter)
}

60. REST
●
Asynchronous and synchronous callback responses
●
Support for HTTP and HTTPS
●
Support for all standard REST methods
●
Support for REST calls during message processing or
WebSocket connection establishment

61. Defining a REST URL Endpoint Constant
public static final MY_REST_URL =
"http://server:port/rest_endpoint"
Referencing the URL Constant
def restRequest =
context.restClient.createRequest(Constants.MY
_REST_URL...);

62. Creating a REST Request
def myRestRequest =
context.restClient.createRequest(Constants.MY
_REST_URL, "PUT");

63. Configuring a REST Request Object
myRestRequest.setAccept(APPLICATION_JSON);
myRestRequest.setAcceptLanguage("en-us", "de-
de", "fr-fr");
myRestRequest.addHeader("My Key", "My
Value");

64. Sending the REST Request
def xml = { mkp.xmlDeclaration() fish
{ name("salmon") price("10") }};
def myRestFuture = myRestRequest.send(xml,
APPLICATION_XML);

65. Sending the REST Request
context.getTaskBuilder("processResponse").wit
hArg("myRestFuture", restFuture)
.onSuccess(restFuture).build();
context.getTaskBuilder("processResponse").wit
hArg("myRestFuture", restFuture)
.onError(restFuture).build();

66. REST Response Handler
void processResponse(TemplateContext context)
{
def result =
context.taskArgs.restFuture.get()
if (result.status == 200) {
def fish = result.value()
if (fish.name.text() == "salmon") {
// Continue processing...
}
} else {
// Handle any errors...
}
}

67. REST Authentication
def myRestAuthRequest =
context.restClient.createRequest(Constants.MY
_REST_URL, "PUT", true);
def username = "myuserid";
def password = [231, 245, 675, 232, 123] as
byte[];
myRestAuthRequest.setCredentials(username,
password);

69. tadhack.optaresolutions.com

70. Add easily
telecom services
to your APPs

71. Industry-
standard SIP
servlet 2.0,
media control
and Java EE

72. Example SIP POJO (JSR-359)
@SipServlet
public class FooPOJO {
@Invite
public void incomingCall(SipServletRequest request) {
//...
}
@Bye
public void disconnectCall(SipServletResponse response) {
//...
}
}

73. WebRTC

74. Summary
●
WebRTC is a great option to implement or add Real
Time Communication services.
●
Groovy is very good in network systems: it provides
flexibility, easy to use and good performance
●
If you like communications & developing, don't miss
TADHack 2015.

75. Q & A

76. Thanks!
@antonmry
www.
serviceandnetworkevolution
.com