[SOLVED] Errors when parsing some ISO8583 fields

Errors when parsing some ISO8583 fields

I am evaluating j8583 as a library to parse ISO8583 messages. It works as expected for almost all fields but I am having trouble getting the correct value for Field 33.

I have created the following unit test:

@Test
public void testDecode() throws IOException, ParseException {
    MessageFactory<IsoMessage> messageFactory = ConfigParser.createFromClasspathConfig("j8583.xml");
    messageFactory.setUseBinaryMessages(true);

    String testData = "0100000000018000000006560103095900000360";
    IsoMessage isoMessage = messageFactory.parseMessage(HexCodec.hexDecode(testData), 0);

    assertEquals("560103", isoMessage.getField(32).toString());
    assertEquals("590000036", isoMessage.getField(33).toString());

}

And here is my config

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE j8583-config PUBLIC "-//J8583//DTD CONFIG 1.0//EN" "http://j8583.sourceforge.net/j8583.dtd">

<j8583-config>

    <parse type="0100">
        <field num="32" type="LLBCDBIN" length="11"/>
        <field num="33" type="LLBCDBIN" length="11"/>
    </parse>

</j8583-config>

When running the unit test Field 32 is parsed correctly, but 33 fails. The value I get for Field 33 is 900000360

Since they are both configured the same and the data seems to be the same (06560103095900000360), I don't understand why this does not parse correctly

Solution

For odd lengths, the values are left-padded, not right-padded. So the first nibble is ignored, not the last one.

I'm sorry it's not clear in the documentation. I'll amend it to specify this.