i'm new to Netty and intend to create a tcp socket server which reads the info of each client and replies back towards client before processing requests immediately ,i.e. sort of an acknowledgement towards client as and when the message enters overriden channelRead method of ChannelInboundHandlerAdapter class.
Please guide me in the above specified objective.
i'm currently trying the basic netty 4.1.4 echo server example however i wanted server to send back acknowledgement to the client so i updated channelread method as follows :
#Override
public void channelRead(ChannelHandlerContext ctx, Object msg) {
ctx.write(msg);
ChannelFuture cf = ctx.channel().write("FROM SERVER");
System.out.println("Channelfuture is "+cf);
}
and the output obtained was as follows:
Channelfuture is DefaultChannelPromise#3f4ee9dd(failure: java.lang.UnsupportedOperationException: unsupported message type: String (expected: ByteBuf, FileRegion))
I understand the error that it is expecting bytebuf but how do i achieve it? also, whether this method would be able to send out acknowledgement towards client
You can use String.getBytes(Charset) and Unpooled.wrappedBuffer(byte[]) to convert to ByteBuf.
ChannelFuture cf = ctx.channel()
.write(Unpooled.wrappedBuffer("FROM SERVER".getBytes(CharsetUtil.UTF_8)));
Also note that ctx.channel().write(...); may not be what you want. Consider ctx.write(...); instead. The difference is that if your handler is a ChannelDuplexHandler it would receive a write event when you do channel().write(). Using ctx instead of channel will send the write out from your handlers point in the pipeline instead of from the end of the pipeline, which is usually what you want.
Related
I'm working with a Camel flow that uses a Netty TCP socket consumer to receive messages from a client program (which is outside of my control). The client should be opening a socket, sending us one message, then closing the socket, but we've been seeing cases where instead of one message Camel is "splitting" the text stream into two parts and trying to process them separately.
So I'm trying to figure out, since you can re-use the same socket for multiple Camel messages, but TCP sockets don't have a built-in concept of "frames" or a standard for message delimiters, how does Camel decide that a complete message has been received and is ready to process? I haven't been able to find a documented answer to this in the Netty component docs (https://camel.apache.org/components/3.15.x/netty-component.html), although maybe I'm missing something.
From playing around with a test script, it seems like one answer is "Camel assumes a message is complete and should be processed if it goes more than 1ms without receiving any input on the socket". Is this a correct statement, and if so is this behavior documented anywhere? Is there any way to change or configure this behavior? Really what I would prefer is for Camel to wait for an ETX character (or a much longer timeout) before processing a message, is that possible to set up?
Here's my test setup:
Camel flow:
from("netty:tcp://localhost:3003")
.log("Received: ${body}");
Python snippet:
DELAY_MS = 3
def send_msg(sock, msg):
print("Sending message: <{}>".format(msg))
if not sock.sendall(msg.encode()) is None:
print("Message failed to send")
time.sleep(DELAY_MS / 1000.0)
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
try:
print("Using DELAY_MS: {}".format(str(DELAY_MS)))
s.connect((args.hostname, args.port))
cutoff = int(math.floor(len(args.msg) / 2))
msg1 = args.msg[:cutoff]
send_msg(s, msg1)
msg2 = args.msg[cutoff:]
send_msg(s, msg2)
response = s.recv(1024)
except Exception as e:
print(e)
finally:
s.close()
I can see that with DELAY_MS=1 Camel logs one single message:
2022-02-21 16:54:40.689 INFO 19429 --- [erExecutorGroup] route1 : Received: a long string sent over the socket
But with DELAY_MS=2 it logs two separate messages:
2022-02-21 16:56:12.899 INFO 19429 --- [erExecutorGroup] route1 : Received: a long string sen
2022-02-21 16:56:12.899 INFO 19429 --- [erExecutorGroup] route1 : Received: t over the socket
After doing some more research, it seems like what I need to do is add a delimiter-based FrameDecoder to the decoders list.
Setting it up like this:
from("netty:tcp://localhost:3003?sync=true"
+ "&decoders=#frameDecoder,#stringDecoder"
+ "&encoders=#stringEncoder")
where frameDecoder is provided by
#Bean
ChannelHandlerFactory frameDecoder() {
ByteBuf[] ETX_DELIM = new ByteBuf[] { Unpooled.wrappedBuffer(new byte[] { (char)3 }) };
return ChannelHandlerFactories.newDelimiterBasedFrameDecoder(1024, ETX_DELIM,
false, "tcp");
}
seems to do the trick.
On the flip side though, it seems like this will hang indefinitely (or until lower-level TCP timeouts kick in?) if an ETX frame is not received, and I can't figure out any way to set a timeout on the decoder, so would still be eager for input if anyone knows how to do that.
I think the default "timeout" behavior I was seeing might've just been an artifact of Netty's read loop speed -- How does netty determine when a read is complete?
I am using a FIX protocol to communicate with one of our counterparties. I have used Camel with Spring to build my communication routes.
I have a requirement where in my counterparty is expecting an ACK for every request it sends to me.
For example:
TradeCaptureRequestAck in response to TradeCaptureRequest
AllocationReportAck in response to AllocationReport
Confirmation_Ack in response to Confirmation
They are expecting a response irrespective of what happens at our end (even if something fails or exception occurs).
One way I know we can intercept the incoming message via MessageFactory. We can create a custom messagefactory and inject it in while creating QuickFixJComponent bean.
Problem with this approach is at factory level I will just be able to get the message type like TradeCaptureReport, AllocationReport etc. but not the content because factory only creates (and returns) the appropriate Message object. Actual work of populating this message object with incoming message data happens in Session class I guess (not sure about this).
Can someone please tell me if there is a way I can get or intercept the request message as soon as it reaches the route so that I can send the appropriate ACK to counterparty?
We are using Akka HTTP to handle our web socket connections using the akka streams API. We are using a Flow that pipes the incoming messages to a "connection actor". A snippet of the code is below:
val connection = system.actorOf(ConnectionActor.props())
val in = Flow[Message]
.to(Sink.actorRef[Message](connection, WebSocketClosed))
val out = Source
.actorRef[Message](500, OverflowStrategy.fail)
.mapMaterializedValue(ws => connection ! WebSocketOpened(ws))
Flow.fromSinkAndSource(in, out)
When the web socket is closed, the connection actor is sent the "WebSocketClose" message and we clean up internal resources. We now have the requirement to know what the reason for closing the connection was according to the standard WebSocket CloseEvent codes.
Is there a way to get the close code from Akka HTTP and send it on to the connection actor so it can take the appropriate action?
I was able to handle client (browser) error code in an akka-http 10.2.6 server.
My use case was to pipe incoming messages to a Sink created by ActorSink.actorRef[T](). When creating the sink, 2 callbacks onCompleteMessage onFailureMessage can be set to converts normal WebSocket close (code=1000) or error to our custom message types.
I suppose that client close/error maps to Flow complete/failure, that means other sinks should be able to handle close/error in a similar way.
my code
`
As it turns out, this is not presently possible in Akka HTTP. See the following GitHub issue:
https://github.com/akka/akka-http/issues/2458
It looks as though this will need to be addressed before this is possible.
I have implemented TCP socket server which accepts incoming XML messages from client. I could send messages through telnet.
But when I am trying to establish connection and send message through python script, I was getting IOException:CRLF not found before max message length: 2048.So I have added ByteArrayLengthHeaderSerializer to serialize and deserialize, but now I am getting below error.
IOException:Message length 1014132591 exceeds max message length: 2048
Though I am increasing the max message length I am getting IOException:Stream closed after 46 of 1014132591
Could someone let me know how to fix the issue.
final AbstractServerConnectionFactory crLfServer = context.getBean(AbstractServerConnectionFactory.class);
ByteArrayLengthHeaderSerializer serializer = new ByteArrayLengthHeaderSerializer();
serializer.setMaxMessageSize(1000 * 1024);
crLfServer.setSerializer(serializer);
crLfServer.setDeserializer(serializer);
I have implemented using Spring Integration.Below is the snippet for my inbound adapter
#Bean
public TcpReceivingChannelAdapter inboundAdapter(AbstractServerConnectionFactory connectionFactory) {
System.out.println("Creating inbound adapter");
TcpReceivingChannelAdapter inbound = new TcpReceivingChannelAdapter();
inbound.setConnectionFactory(connectionFactory);
//inbound.
inbound.setOutputChannel(fromTcp());
return inbound;
}
I think might be better to send exactly that CRLF in your script after the message. That will be exactly delimiter for the messages to deserialize. This is one what is used by the mentioned Telnet. However you need to come back to the default deserializer in the connection factory configuration.
I am looking into the Swift Vapor framework.
I am trying to create a controller class that maps data obtained on an SSL link to a third party system (an Asterisk PBX server..) into a response body that is sent over some time down to the client.
So I need to send received text lines (obtained separately on the SSL connection) as they get in, without waiting for a 'complete response' to be constructed.
Seeing this example:
return Response(status: .ok) { chunker in
for name in ["joe\n", "pam\n", "cheryl\n"] {
sleep(1)
try chunker.send(name)
}
try chunker.close()
}
I thought it might be the way to go.
But what I see connecting to the Vapor server is that the REST call waits for the loop to complete, before the three lines are received as result.
How can I obtain to have try chunker.send(name) send it's characters back the client without first waiting for the loop to complete?
In the real code the controller method can potentially keep an HTTP connection to the client open for a long time, sending Asterisk activity data to the client as soon as it is obtained. So each .send(name) should actually pass immediately data to the client, not waiting for the final .close() call.
Adding a try chunker.flush() did not produce any better result..
HTTP requests aren't really designed to work like that. Different browsers and clients will function differently depending on their implementations.
For instance, if you connect with telnet to the chunker example you pasted, you will see the data is sent every second. But Safari on the other hand will wait for the entire response before displaying.
If you want to send chunked data like this reliably, you should use a protocol like WebSockets that is designed for it.