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From Phil White <pwhite...@gmail.com>
Subject Re: Message bandwidth/overheads - how to reduce?
Date Fri, 05 Aug 2011 14:02:37 GMT
Thanks Tim

I don't think these additional messages are connection/subscribe related
though; I'm pushing 100 messages out of the publisher, one every second, and
see the same sequence between each message. Also the 243 packets come
immediately after the message, whereas I would have expected keep-alives to
been seen in the absence of message traffic, rather than being triggered by
it. Here's a typical packet sequence pulled out of Wireshark:

--> The message itself
23685	99.657686	192.168.1.74	192.168.1.76	TCP	580	61616 > eisport [PSH, ACK]
Seq=51034 Ack=18744 Win=16987 Len=526	23685

--> First set of following small packets
23686	99.658418	192.168.1.76	192.168.1.74	TCP	58	eisport > 61616 [PSH, ACK]
Seq=18744 Ack=51560 Win=64483 Len=4	23686
23687	99.658530	192.168.1.76	192.168.1.74	TCP	55	eisport > 61616 [PSH, ACK]
Seq=18748 Ack=51560 Win=64483 Len=1	23687
23688	99.658591	192.168.1.76	192.168.1.74	TCP	55	eisport > 61616 [PSH, ACK]
Seq=18749 Ack=51560 Win=64483 Len=1	23688
23689	99.658690	192.168.1.74	192.168.1.76	TCP	60	61616 > eisport [ACK]
Seq=51560 Ack=18749 Win=16982 Len=0	23689
.....
23928	99.675329	192.168.1.74	192.168.1.76	TCP	60	61616 > eisport [ACK]
Seq=51560 Ack=18937 Win=16794 Len=0	23928

--> Next message
23929	100.623848	192.168.1.74	192.168.1.76	TCP	580	61616 > eisport [PSH,
ACK] Seq=51560 Ack=18937 Win=16794 Len=526	23929

The second column is the Wireshark time, so the 580 byte message appears at
99.657686 and the first of the small packets at 99.658418 (a
subscriber->broker packet - I guess "eisport" is Wireshark's attempt to
interpret the ephemeral return port number).

But as I mentioned these additional mystery packets are *only *seen if
wireFormat.tightEncodingEnabled=true, otherwise the number of packets per
message comes down to 3.

However my main concern is the message packet size itself rather than the
additional 'chatter'. The minimum message size I've managed to achieve so
far, which is for a type-less, parameter-less, body-less message is 329
bytes of data (383 bytes on the wire). That seems like a huge overhead when
only sending small status messages comprising a few properties (obviously
less of a concern if the message body runs into many KB or MB).

Are there any further options for reducing this size ?

Thanks again -

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