HL7 client

["Trustin Lee (이희승)"]

Hi John,

It seems like you are spinning in the loop, which is inefficient.  I'd
use BlockingQueue instead of ChannelLocal.  Please refer to the
FactorialClient example, which uses LinkedBlockingQueue:

    http://is.gd/bL5iX

HTH,
Trustin

John DeStefano wrote:
> Hi,
> 
> We are working on HL7 connectivity for the JBoss ESB. We have implemented a
> simple frame based server in netty to receive HL7 messages using MLLP
> protocol. We are working on the client side now. The client initiates a
> session with the server and sends an HL7 formatted message to the server.
> The server responds with an ACK message which indicates that the message was
> received and a code tells the status of the message.
> 
> Out issue is around how to synchronize the sending of the message with the
> receiving of an ACK. Currently we send a message as follows:
> 
> // Sends message
> lastWriteFuture =
> channel.write(message.getBody().get(Body.DEFAULT_LOCATION));
> 
> // wait for it t complete
> completed =
> lastWriteFuture.awaitUninterruptibly(responseReceiveTimeoutMillis);
> 
> If the send completed ok the we wait for the response:
> 
> while (true) {
> 	if (!channel.isConnected()) {
> 	     throw new Exception("ACK channel has been closed.");
> 	}
> 				
> 	// Read the ChannelLocal variable.
> 	// This is where we put the ack message.
> 	// See HL7ClientUpStreamHandler
> 	// If the clientACK is not null put it in the message
> 	// Remove the channel from the ChannelLocal variable 
> 	// and wait for the next one
> 	String ack = ClientAckState.clientACK.get(channel);
> 	if (ack != null) {
> 		ClientAckState.clientACK.remove(channel);
> 		message.getBody().add(ackLocation, ack);
> 		break;
> 	}
> }
> 
> In the SimpleChannelUpStreamHandler we put the received ACK in a
> ChannelLocal variable:
> 
> public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) {
>       if (e.getMessage() instanceof String) {
> 	     ClientAckState.clientACK.set(e.getChannel(), (String) e.getMessage());
>       }
> }
> 
> Is this the right way to handle the synchronization of sending a message and
> wating for the reply?
> 
> Thanks
> 
> 

-- 
what we call human nature in actuality is human habit
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