MQSeries.net :: View topic - XMLNSC Problem - What should be '' being interpreted as NULL

ccrandall · Posted: Mon Aug 16, 2010 3:14 pm Post subject:

In my Message Broker framework, we use a XML-based "catalog" to store configuration data. For each incoming request message that is supported, there is typically an entry in the catalog and we match the request message with this entry based on the message name, version, and something called an application function. The framework contains a Java class that reads and parses the XML and places it into the LocalEnvironment. As part of our upgrade to Message Broker 7.0, I'm changing the framework to use the XMLNSC parser. Previously we used the XML parser.

A portion of the catalog that contains these 3 matching parameters looks like this:

<SwitchRecord>
<DiscoveryKey>
<messageName>GetSampleSubjectsForLE</messageName>
<messageVersion>002</messageVersion>
<appFunction/>
</DiscoveryKey>

The Java code that is used to read in the catalog looks like this:

MbMessage aMsgEnvL = new MbMessage(assembly.getLocalEnvironment());
MbElement aNewEnv = aMsgEnvL.getRootElement();

MbElement aVarChild = aNewEnv.getFirstElementByPath("/Variables");
if (aVarChild == null)
{
aVarChild = aNewEnv.createElementAsLastChild("XMLNSC");
aVarChild.setName("Variables");
}

String strXML = getXML(fileLocation);
aVarChild.createElementAsLastChildFromBitstream
(
strXML.getBytes(),
"XMLNSC",
"", "", "",
0, 0, 0
);

After reading the catalog, a user trace showing the LocalEnvironment shows:

(0x01000000:Folder ):SwitchRecord = (
(0x01000000:Folder):DiscoveryKey = (
(0x03000000:PCDataField):messageName = 'GetSampleSubjectsForLE' (CHARACTER)
(0x03000000:PCDataField):messageVersion = '002' (CHARACTER)
(0x01000000:Folder ):appFunction =
)

What bothers me here is that appFunction is interpreted as a Folder with no value instead of a PCDataField with '' for the value.

The catalog is then read into a shared variable:

DECLARE ServiceCatTable SHARED ROW;
SET ServiceCatTable = LocalEnvironment.Variables.XMLNSC;

When the request message is read in, the 3 parameters used to match configuration data in the catalog are put into a RoutingData tree in the Environment. The RoutingData is defined as being in the XMLNSC domain:

CREATE LASTCHILD OF Environment.Variables DOMAIN('XMLNSC') Name 'RoutingData';

When I look at Environment.Variables.RoutingData in the user trace, those 3 matching parameters look like this:

(0x01000000:Folder):RoutingData = ( ['xmlnsc' : 0x1369b2a0]
...
(0x03000000:PCDataField):MessageName = 'GetSampleSubjectsForLE' (CHARACTER)
(0x03000000:PCDataField):MessageVersion = '002' (CHARACTER)
(0x03000000:PCDataField):ApplicationFunction = '' (CHARACTER)
)

Here, the ApplicationFunction is as I expect it to be where it's of type PCDataField with '' as the value.

So, when I try to finding a matching record in the catalog for a case where the application function is empty:

SET Environment.Variables.SwitchRecord =
THE(SELECT ITEM R
FROM ServiceCatTable.MessagingSwitchServiceCatalog.SwitchRecord[] AS R
WHERE R.DiscoveryKey.messageName=Environment.Variables.RoutingData.MessageName AND
R.DiscoveryKey.messageVersion=Environment.Variables.RoutingData.MessageVersion AND
R.DiscoveryKey.appFunction=Environment.Variables.RoutingData.ApplicationFunction);

I don't find a match because R.DiscoveryKey.appFunction evaluates to NULL while Environment.Variables.RoutingData.ApplicationFunction evaluates to ''. I tried wrapping both sides with a FIELDVALUE call, but that didn't help either.

I hope I've provided enough information here to understand what's going on. If anyone can point out my error, I would really appreciate it!

Thank you
Curt