how to setup a signaling server for webRTC when the system are connected in Local Area Network? Its mandatory that we must use STUN and TURN server for signaling?
To make WebRTC run on LAN, you will require to have a signaling server in that LAN. A signaling server is any web server that will allow your web clients to exchange the SDP offer/answer and ICE candidates that are generated by the WebRTC PeerConnection. This can be done using AJAX or WebSockets.
I have listed some top sources for information about WebRTC. Please go through some of the links on that page to better understand how the WebRTC signaling works.
You will not require a STUN/TURN server as your WebRTC clients (i.e. Web Browser) will be in the LAN and accessible to each other. FYI... STUN/TURN servers are not part of the signaling but part of the media leg and usually required for NAT traversals of media.
Webrtc needs some kind of signalling system for initial negotiation.. like transferring SDP, ICE-candidates, sending and receiving offers etc... rest is done by peer-peer connection. For initial signalling you can use any technique like sending AJAX calls, using socket.io etc.
STUN and TURN servers are required for NAT traversal, NAT traversal is important because it is needed for determining the path between peers. You can use google provided STUN/TURN server address stun:stun.l.google.com:19302 etc , or you can configure your own turn server by using rfc-5766 turn server
Making signalling server for WebRTC is quite easy.
I used PHP, MYSQL and AJAX to maintain signalling data.
Suppose A wants to call B.
Then A creates offer using createOffer method. This method returns an offer object.
You have to transfer this offer object to user B, This is a part of signalling process.
Now create MYSQL database, having columns :
caller, callee, offer, answer, callerICE and calleeICE
Now offer created by A is stored in offer attribute with the help of AJAX call .
(Remember to use JSON.stringify the JS object before "POSTing" object to server.)
Now user B scans this offer attribute created by caller A , again with the help of AJAX call.
In this way , offer object created at user A can arrive at user B.
Now, user B responds to the offer by calling createAnswer method. This method returns answer object. This can again be stored in "answer" attribute of database.
Then the caller A scans this "answer" attribute created by callee B.
In this way, answer object created by B can arrive at A.
To store iceCandidate object representing caller A, use "callerIce" attribute of MYSQL table. Note that, callee B is scanning "callerIce" to know the details of caller A.
In this way we can transfer the iceCandidate objects representing future peer.
After you complete transferring of iceCandidate object, the connectionState property holds "connected" indicating two peers are connected.
If any questions, let me know!
Cheers ! You can now share local media stream to the remote peer.
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Not sure the title makes a lot of sense. To add some context, we are building a WebRTC infrastructure and to so do we have a few STUN servers up and and running.
We sometimes have users complaining of call taking too long to connect therefore we would like to get some analytics on the calls. Because we provide a list of STUN IPs (including some public STUN as backup), we would like to detect the STUN server that successfully initiated the call.
We have collected a bunch of information thanks to RTCPeerConnection.getStats but there is nothing related to the STUN itself. So for my questions:
is there any JS API that allow us to retrieve the STUN used?
is there any tool that I am not aware of that could do the job?
do the SDP contains any information related to STUN?
Hope all of this is clear, thanks for your kind replies
The statistics do contain a server url:
https://w3c.github.io/webrtc-stats/#dom-rtcicecandidatestats-url
However, that is not implemented and since STUN servers are not involved in the actual call that information is unlikely to be useful.
For TURN servers you can get the active candidate pair and the IP of any relay involved from getStats. See https://webrtc.github.io/samples/src/content/peerconnection/constraints/ for a sample that shows how to determine the active candidate pair.
Let's say I have an application that has a list of live streamers who are currently broadcasting via WebRTC. In order for a device to plug into a particular broadcaster, they need to send their SDP to the specific broadcaster that they click on.
So I gather my local SDP information, and send that to the Signaling server to be transferred to the broadcaster and await the answer.
My question is, how does the signaling server know which broadcaster to send this SDP to? And where do you store this identifier?
My first thought was use the ip address as the unique identifier but that can change as I move around and change connections.
And is it normal to store this identifier on the web socket itself as a property? I don't know how else you would know which web socket to send along the SDP?
Sorry if this is a n00b question, very new to WebRTC.
I also faced same situation like you.
In my case, I used Socket.IO for bidirectional communication.
So what I did is using member's id and socket.io's room.
When socket.io client connected to server, this client joined specific room automatically.
That room's name is client's socket ID. You can check this doc.
For example, your service is broadcasting. right?
And maybe broadcasters in your service have unique id (in Database).
So when client is connected to server, escape from default room immediately, and join new room that name is client's unique id.
Then, now you can send some messages like sdp to specific client with client's unique id.
To establish WebRTC connections the ICE protocol is used with a signaling server which must send messages in both directions. I wonder why after the initiator sent its offer and candidates to the other participant, the participant needed to send back its answer and candidates using the signaling channel in the other direction. Cannot the participant open the connection to the initiator using candidates from both sides and send back its answer using the open connection?
I started reading ICE RFC and the only relevant part I found is in section 5.2 where the initiator must take the controlling role and nominates candidate pairs. But it does not explain why the other could not initiate connection.
To give some background, I am trying to build a webapp for which I want users to establish WebRTC connections without using a signaling server. I thought of having the app to generate a URL including the offer and candidates and providing this URL to other participants through other medium like instant messaging. The issue I got is that the participant need to send back its answer and candidates using the same medium, which is not practical. In the end I will go for a signalling server but I wonder the technical reason.
Yes, you can do that if caller is behind public IP or Full Cone NAT(in this case, router connection mapping needs not to be timed out).
You can able full fill above conditions rarely.
What's the problem with other NAT types?
For example , PRC(port restricted cone) NAT won't allow you to receive a packet from a IP:Port , if you didn't send any packet to that IP:Port before. So callee will never able to send you a packet.
So if callee sends her candidates list to you . you can send some dummy data(with low TTL) to her IP:Port to fool your PRC NAT (now it allow incoming packets from callee's IP:Port as it sends a packet to that IP:Port before).
To know more about different types of NAT:
https://en.wikipedia.org/wiki/Network_address_translation
http://think-like-a-computer.com/2011/09/16/types-of-nat/
Signaling is not addressed by WebRTC (even if we do have JSEP as a starting point), but from what I understand, it works that way :
client tells the server it's available at X
server holds that information and maps it to an identifier
other client comes and sends an identifier to get connection information from the first client
other client uses it to create it's one connection information and sends it to the server
server sends this to first client
both client can now talk
This is all nice and well, but what happends if a 3rd client arrives ?
You have to redo the whole things. Which suppose the first two clients are STILL connected to the server, waiting for a 3rd client to signal itself, and start the exchanging process again so they can get the 3rd client connection information.
So does it mean you are required to have to sort of permanent link to the server for each client (long polling, websocket, etc) ? If yes, is there a way to do that efficiently ?
Cause I don't see the point of having webRTC if I have to setup nodejs or tornado and make it scales to the number of my users. It doesn't sound very p2pish to me.
Please tell me I missed something.
What about a chat system? Do you really need to keep a permanent link to the server for each client? Of course, because otherwise you have no way of keeping track of a user's status. This "permanent" link can be done different ways: you mentioned WebSocket and long polling, but simple periodic XHR polling works too (although this will affect the UX, depending on the interval).
So view it like a chat system, except that the media stream is P2P for reduced latency. Once a P2P WebRTC connection is established, the server may die and, of course, the P2P connection will be kept between the two clients. What I mean is: both users may always block your server once the P2P connection is established and still be connected together in the wild Internets.
Understand me well: once the P2P connection is established, your server will not be doing any more WebRTC signalling. The connection is only needed to keep track of the statuses.
So it depends on your application. If you want to keep the statuses of users and make them visible to others, then you're in the same situation as a chat system: you need to keep a certain link, somehow, to make sure their statuses are synced. Otherwise, your server exists to connect them together and is not needed afterwards. An example of the latter situation is: a user goes to a webpage, the webpage provides him with a new room URL, the user shares this URL to another peer by another mean, the other peer joins the room, server connects them together (manages WebRTC signalling) and then forgets them. They are now connected until one of them breaks the link. Just like this reference app.
Instead of a central server keeping one connection per client, a mesh network could also be considered, albeit difficult to implement.
I want to use WCF to enable two way communication without opening a port on the client.
I'm developing something like a P2P application (similar to teamviewer/logmein) where you don't need to open ports to communicate.
How do I accomplish two way communication through HTTP/HTTPS without the need to open a port in the client?
Note : Port 80 can be opened in the server...no issues on that.
Thanks
Well those systems you mention work as follows. They first try to make client A and client B communicate directly via a range of different topologies which basically require one of them to allow incoming connections if that fails they fall back on a third party which acts as a man in the middle. So client A talks to the server and sends it messages for client B. Then Client A gets the messages addressed to it back in response. Client B sends it messages to the server and it's gets the message from client A back from the server. This way both client A and B always initiate the connection and don't need to have a port open for incoming traffic.
If I understand correctly in your case you would always want the man in the middle. In order to do this you would have to write a WCF service that provides all relevant methods. For instance things like
void SendMessageToClient(Guid senderId, Guid recipientId, Message msg)
Message[] GetMessages(Guid recipientId)
then have those methods respectively store and retrieve those Message objects from somewhere (like a database or a queue or something).
Then write a client that connects to the WCF service using the HTTP binding and call the methods on the server and process the results.
I hope you understand that
a) this isn't a very efficient way to communicate.
b) that it's difficult to test and debug and understand whats going on since there are so many parties involved and communication is asynchronous living in 3 different processes.
c) it adds an extra layer ontop of the communication so you need to keep it clear for yourself in your head (and prefereably in code) when you are dealing with the infrastructure bits and when you are dealing with the actual protocol clientA and clientB speak to each other in the Message objects.
Pseudo (code) Example
in this example I assume the message object is nothing more then a string and the only command is "whattimeisit" to which the response is the local time in string form
ClientA makes call to server.SendMessageToClient("clientA", "clientB", "whattimeisit");
Server stores this message in the database with ID 1
ClientB makes call to server GetMessages("clientB");
Server retrieves message with ID 1
ClientB recieves back "whattimeisit" as a response
ClientB makes call to server.SendMessageToClient("clientB", "clientA", "19:50:12");
Server stores this message in the database with ID 2
ClientA makes call to server GetMessages("clientA");
Server retrieves message with ID 2
ClientA recieves back "19:50:12" as a response
I'm not sure I understand. The purpose of digital firewalls is (generally) control communication channels. If you want to communicate bypassing firewalls you have two choices.
Hide the message in something the firewall lets through
Use a communications channel the firewall doesn't control
In the case of the earlier:
You could pass messages to proxy that passed them on (email is a good but not exactly responsive example).
In the case of the latter:
You could put the messages on say file where some other transport layer carries them