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Re: [xmlblaster] publishing a message for a subscriber that doesnt run

Radu Maierean wrote:
hi there,

i'm pretty sure this is about my lack of understanding about how
XMLblaster messages work, but i cant figure it out at all. here's what

in my environment, application A (which is a publisher) needs to send
some commands to application B (which is a subscriber); application B
should respond with a ptp message back to A upon executing the command.
when it is first started, application A needs to make sure that
application B is alive, therefore it goes into a loop and posts dummy
commands for application B, every 3 seconds, until it gets a response.
these dummy messages are sent with the following <qos> tag:
<qos><expiration lifetime="3000"/></qos>
(i also tried adding the <forceUpdate>false</forceUpdate> with the same
results). B subscribes to the messages published by A with the following
(again, i also tried adding a <history numEntries='20'
newestFirst='true'/> - same results).

everything is fine if application B is already started when A starts - a
response is sent back from B to A, and A breaks off that loop and enters
normal operation. however, if A (the publisher) starts before B, a lot
of times B doesnt seem to receive the messages published by A (i can say
this since B would log every single message that it receives). again -
sometimes it does receive them, sometimes it doesnt - and i cant
understand why this is happening. both my apps are written with the C
sockets library.

can anybody help with an advice to make this work consistently?...
thanks. (let me know if more information is needed from me.)


i can imagine a case where the history of the topic is zero

  queue/history/maxEntries=0   (any setting <= 0)

in this case xmlBlaster has no memory for the topic and the subscriber B
wouldn't get the existing message from A, but should receive the
first one send after successful subscription.

Can you extract a small, working C code which shows the problem?



Radu Maierean
JamboTECH phone: 818-676-3452
email: radu at jambotech.com