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Publish and Subscribe question
This is a followup on some of my previous questions - Everything has worked
wonderfully so far, I just need some clarification on publishing and
I have been able to publish XML documents via the xmlKey and query on the
document with an XPath expression. I am using derivatives of the
..client.reader.SubscribeMessage client programs. Let's call them MyPublish
and MySubscribe respectively.
1. Does client order matter?
For example, I get a "null" pointer exception if I first run the MyPublish
the client followed by the MySubscribe client. The exception occurs in the
RequestBroker.subscribeToOid method because the xmlKey object is null.
If I run MySubscribe first followed by the MyPublish, the XML document is
successfully passed to the subscribing client. I was under the impression
that the messages were persistent with xmlBlaster, so the order in which
clients interacted didn't matter. The following are the commandline options
I was using - perhaps I have the Qos options incorrect.
First: jaco MyPublish -k MyXmlFile.xml -content " "
Second: jaco MySubscribe -xpath "//[ at oid=\"410\"]"
If I restart the xmlBlaster server and run the clients in reverse order
(i.e. MySubscribe and then MyPublish) I don't get the null pointer exception
and the client receives the XML document via the xmlKey parameter.
2. How can I publish multiple XML documents from the same client?
Another problem occurs after I start MySubscribe client and try to send
multiple XML files using the MyPublish client. MySubscribe client receives
the first XML message fine, but subsequent messages are not received by the
client even when the XPath is still valid. Shouldn't xmlBlaster notify the
client when a new message is received by another publisher?
Any help would again be appreciated.
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