Faye allows you to monitor various events, such as handshake or subscribe. These callback blocks are only supplied the client_id value rather than the client itself. For example:
server = Faye::RackAdapter.new(mount: '/faye', timeout: 45)
server.bind(:handshake) do |client_id|
puts "Received handshake from #{client_id}"
end
How can I access the client given the client_id? Or how can I access more information in the handshake, such as cookies provided in the request header (if that info is even available)?
I think my original question is based upon a lack of understanding on how Faye works in two regards. Instead of deleting my question, I'm going to answer it for anyone else who comes across this with a similar question. (If my answer is wrong in any way, please comment or edit!)
First, at no point is access to the connected client available due to the way Faye is implemented with regards to the Bayeux protocol. All communications are carried out via channel broadcasting, meaning all connections listening to a channel will receive the message being sent.
Second, the code I pasted in the question deals with monitoring. What I'm really looking for is an extension.
In order to achieve authentication given my original question, I need to pass whatever authentication value is needed (whether it's a cookie value, auth token, etc.) as part of the message['ext'] value (per the example on the extensions page). Then, on the server side, I need to listen for messages on the /meta/handshake channel, setting message['error'] to some value in the case of value.
Related
I am building an application which can have multiple gRPC servers and definitely will have multiple gRPC clients, I wanted to know, how to identify on server side that this is the client I am talking to and only send data to that client. I am using bidirectional streaming RPC and right now the data gets broadcasted to every client and I don't want that. What functions in go gRPC make it possible or how can I implement it?
There are two ways to read this question. One way is to read it as the auth problem as answered before. The second way is how I read it, as a connection/session problem.
When the client connects, the grpc server will invoke a function to implement the call in its own goroutine, and that function will be only talking to the client that initiated that call. So, the struct you registered as your grpc server will be shared among many connections, but each connection will run in its own goroutine, and will only talk to the client that initiated it. That also means you have to make sure the grpc server implementation is thread-safe.
You mentioned data is being broadcasted to every client? There is no broadcast in grpc, are you sure that's what's happening?
This sounds like a common authentication/authorization problem that ultimately won't have much to do with gRPC or Go.
You need a way for a client to indicate who they are. Personally I'm a fan of JWTs. In a standard HTTP request, there are authorization headers that can indicate who is making the request. Similarly, gRPC supports meta data attached to each remote call. In my current work project, every call must have a JWT in the meta data or else I don't process the request. Every call except the login endpoint that is.
I haven't looked into how to get details like a gRPC client's IP address or other information about a client's connection but chances are that anything provided by gRPC's generated code is something potentially faked by the client. When architected correctly, JWTs can offer cryptographic confidence that the client is who they claim to be.
I am going to develop an application which includes Audio/Video/Text chat.
I read IceLink documentation and demo. From that what I understood is we need to do signalling using WebSync to connect two peers.
But I couldn’t understand how to do it.
My questions are (suppose A wants to call B):
1. How A knows the address of B (whatever it may be like, ID or anything)
2. How B comes to know that A is calling him/her
We once build an App with P2P Connection via IceLink.
But we didn´t use the WebSync Component.
To establish a RTC Connection you need a non-P2P communcation to do the Handshake first.
With this Handshake all neccessary information is transmitted, and icelink can try to reach the other peer.
We used Microsoft SignalR for that since it is a serverside-javascript which can push messages to connected clients.
1.this is part of the handshake
2.Signaling via SignalR (e.g.)
I followed their example and achieved the same thing as you are intending to.
You need to handle call making on the server-side and somehow communicate the session id to another user . as simple as that.
I'm trying to implement the basic DEALER - ROUTER socket in ZeroMQ.
My Question has multiple parts.
Before that, here are my sample scripts
DEALER SCRIPT
ROUTER SCRIPT
QUESTION -
Firstly,The vanilla DEALER SCRIPT of mine is unable to read the message from the SOCKET.
Secondly, When I'm implementing a DEALER or ROUTER PATTERN, is it mandatory to pass the IDENTITY across(as a part of header) i.e can't the message be sent without any IDENTITY.
In other words can a DEALER - ROUTER pattern (can be see below) can co-exists and pass message among themselves without sending identity info in header.
DEALER WITHOUT ANY IDENTITY
ROUTER WITHOUT ANY IDENTITY
because, I'm unable to get it working without the identity as well.
NOTE : - The Zeromq ruby library(ruby client) currently in picture is ffi-rzmq
Your code shows a lot of misunderstandings about how ZMQ works, I suggest you read the guide and follow the Ruby examples to set up your scripts.
Here's the problems that I see:
In your DEALER script, you explicitly receive the identity - it will never get its own identity as part of the message, this is silently removed by ZMQ because it's not intended to be message data, it's intended to be an "address" used by the ROUTER socket. So, you're actually receiving the delimiter into your identity variable, the message into your delimiter variable, and then nothing is left and your msg variable is empty. If you puts the values of all three variables, you'll see it.
You don't need a ZMQ poller in your DEALER socket. Pollers are intended to receive messages from multiple sockets, you're only using one socket. I don't know whether it's actually intended to work with one socket at all, but at any rate it's needless additional complexity, rip it out. See here for a simple send/receive example from the guide (if you just change the socket type to DEALER, add your "particulars" - identity, address, port, etc - and omit the send, it should work for you)
In your second example, where you don't set an identity, the ROUTER socket doesn't address the message to any connected client - you always need to send the client identity as the first frame of the message. Typically, you'll receive a message from your client, which includes its identity, and you'll use that identity to send the message back. You're only able to skip that in the first example because your script already knows the identity, "client"
Websocket example in netty (examples) has a http request handler which:
performs hand shaking (at first)
(then) handles different types of WebSocket frames, eventually "TextWebSocketFrame"s.
There is only one url for websocket connections in this example.
The problem is, when TextWebSocketFrame based actual websocket communication starts, there is no direct way to determine websocket url from TextWebSocketFrames themselves (correct me if I am wrong).
So, how to handle different (url) websocket connections in netty?
One solution can be registering channels and their "websocket connection urls" during handshaking process.
The other is having only one websocket connection url and resolving different contexts by adding extra information to websocket messages (TextWebSocketFrames).
I don't find these solutions elegant, so any ideas?
It is my understanding that when you perform a web socket handshake, it is to a specific URL. That is specified in the web socket standard. See RFC 6455. Hence, there is no URL information in the TextWebSocketFrame because the assumption is that the frame will be sent to the URL to which the socket is bound.
To handle different URLs, you will have to either:
Setup a different pipeline and bind to a different IP and/or port for each URL, or
Like you stated, customise the hand shake and store the URL with the channel.
Personally, I've just used JSON in a TextWebSocketFrame. In my JSON, I have a field that states the intended action. This field is used for routing to the appropriate message handler.
I think it comes down to a design decision. WebSockets are intended for long lived connections where a request message can have 0, 1 or > 1 responses. This contrasts the REST style 1 request and 1 responses model.
Hope this helps.
The question "how to handle different (url) websocket connections in netty" does not make sense, I presume that the author meant to ask "how to serve multiple different websocket paths on a single port:host".
The question is valid because the HTTP protocol, (at least version 1.1,) WebSockets, and web browsers all support this scenario:
Client connects to server and the two start exchanging HTTP request/response pairs.
Client sends the HTTP request to upgrade to WebSocket, server honors it, and now a WebSocket is established between client and server.
The original HTTP connection remains open, so client and server can continue exchanging HTTP request/response pairs in parallel to the WebSocket. (In light of this, the term "upgrade" is a misnomer, because the connection is not upgraded at all; instead, a new connection is established for the WebSocket.)
Since the HTTP connection is still available, the client can send another HTTP upgrade request, thus creating another WebSocket. On the client side, it would look like this:
socket1 = new WebSocket( "https://acme.com:8443/alpha" );
socket2 = new WebSocket( "https://acme.com:8443/bravo" );
However, you can't have that, because Netty in all its magnificent glory and terrifying complexity does not exactly support that, and this is true even now, 10 years after the question was asked.
That's because:
Only one ServerBootstrap can bind to a given port on a given host.
(That's how the socket layer works.)
A ServerBootstrap can only have one "Child Handler".
(ServerBootstrap.childHandler() silently fails to report an error if you invoke it twice, but only the last invocation takes effect.)
A ChannelPipeline can only have one WebSocketServerProtocolHandler.
(Only the first WebSocketServerProtocolHandler that you add works, and Netty silently fails to issue an error if you add more.)
A WebSocketServerProtocolHandler accepts one and only one webSocketPath.
So, there you have it, a port:host can only have one webSocketPath, and that's a Netty limitation.
It might be possible to overcome this limitation by rewriting WebSocketServerProtocolHandler, but #aintNoBodyGotNoTimeFoDat.
Luckily, Netty does support another feature which makes it possible to achieve a similar thing. The constructor of WebSocketServerProtocolHandler supports a poorly documented and poorly named checkStartsWith parameter which, if set to true, will cause the handler to honor websocket negotiation requests not only on the given webSocketPath but also for any webSocket path that starts with the given webSocketpath and continues with a '?' or a '/' followed by other stuff. So, the code on the client would then look like this:
socket1 = new WebSocket( "https://acme.com:8443/allWebSocketsHere/alpha" );
socket2 = new WebSocket( "https://acme.com:8443/allWebSocketsHere/bravo" );
If you decide to build your netty server to handle this, the next problem you will face is how to obtain the "/allWebSocketsHere/alpha" and "allWebSocketsHere/bravo" parts. Luckily, someone else has already figured that out, see "Netty: How to use query string with websocket?" https://stackoverflow.com/a/47897963/773113
I'm refering to the 'A Request-Reply Broker' in the Zeromq documentation: http://zguide.zeromq.org/chapter:all
I'm getting the general gist of the app: it acts like an intermediary and routes messages from the client to the server and back again.
What I'm not getting though is how it makes sure the correct response from a server is sent to the correct client which originally made the request. I don't see anything in the code example which makes sure about this.
Now in the example they only send 1 message (hello) and 1 response (world), so even if messages are mixed up it doesn't matter, but I'm guessing that the testclient and server are kept deliberately simple.
Any thoughts are welcome...
All zeromq sockets implicitly have an identity associated with them. (You can obtain this identity with zmq_getsockopt().)
For bi-directional socket types not XREQ or XREP, this identity is automatically transferred as part of every message sent over the socket. The REP socket uses this identity to route the response message back to the appropriate socket. This has the effect of automatic routing.
Under the hood, identities are transferred via multipart messages. The first message in a multipart message will contain the socket identity. An empty message will follow, followed by all messages specified by the user. The REQ and REP sockets deal with these prefixed messages automatically. However, if you are using XREQ or XREP sockets, you need to populate these identity messages yourself.
If you search for "identity" on the ZMQ Guide, you should find all the details you will ever want to know about how identities and socket routing works.
Ok in chapter 3 they all of a sudden explain that there is an underlying concept of an 'envelope' which the req/resp pattern invisubly uses.
This explains how it works.