#Stomp Exploration
I realized I don't know enought about this protocol I have been using since a while without understanding it throughtfully.
In case you want to debug Stomp communication between broker and clients you should configure the Stomp connector with the trace parameter, like this:
<transportConnectors>
<transportConnector name="stomp" uri="stomp://localhost:61613?trace=true"/>
</transportConnectors>
This will instruct the broker to trace all packets it sends and receives.
Furthermore, you have to enable tracing for the appropriate log. You can achieve that by adding the following to your conf/log4j.properties
log4j.logger.org.apache.activemq.transport.stomp=TRACE
Finally, you will probably want to keep these messages in the separate file instead of polluting the standard broker’s log. You can achieve that with the following log4j configuration:
log4j.appender.stomp=org.apache.log4j.RollingFileAppender
log4j.appender.stomp.file=${activemq.base}/data/stomp.log
log4j.appender.stomp.maxFileSize=1024KB
log4j.appender.stomp.maxBackupIndex=5
log4j.appender.stomp.append=true
log4j.appender.stomp.layout=org.apache.log4j.PatternLayout
log4j.appender.stomp.layout.ConversionPattern=%d \[%-15.15t\] %-5p %-30.30c{1} - %m%n
log4j.logger.org.apache.activemq.transport.stomp=TRACE, stomp
log4j.additivity.org.apache.activemq.transport.stomp=false
# Enable these two lines and disable the above two if you want the frame IO ONLY (e.g., no heart beat messages, inactivity monitor etc).
#log4j.logger.org.apache.activemq.transport.stomp.StompIO=TRACE, stomp
#log4j.additivity.org.apache.activemq.transport.stomp.StompIO=false
After this, all your Stomp packets will be logged to the data/stomp.log
You need to send a custom connection-header hash including:
-
accept-version
-
host example:
connect_headers: {"accept-version" => "1.1,1.2", "host" => `hostname -f`.strip}
First note there is a difference between STOMP1.0 and versions 1.1 or higher:
- STOMP_1.0 has only ack: client
- STOMP_1.1 has also ack: client-individual
The ack cmd is also different, but the client.ack(msg) call
takes care of the differences.
On Activemq nack means: move msg to DLQ.
But to have something sensible, msg have to be persistent
(non-persistent msg are simply discarded) and you'd better
add a individualDeadLetterStrategy. Without it all messages
would add together in a single queue and mess things up.