Simpletype Initial tag in a XML Schema?

Question

Hello,
We have an Oracle 12 EBS implementation, and are using an Advanced Queue dequeue process that can handle a number of XMLType files from different sources as input. The Dequeue procedure right now extracts the value of first field of each of the XML files (which would be a FILETYPE field), and decides which procedure to call. The code used for this is:
v_filetype := message.extract('//FILETYPE/text()').getStringVal();
The procedure called by the de-queue is the one that loads into the XMLType table.
The problem is that I have set up the XML Schema to use a complextype as the first item - and so each different type of XML type would have a different initial tag. For example, suppose there are Purchase Orders and Employees coming through the queue. The Purchase Order Schema file starts like this (example):
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:xdb="http://xmlns.oracle.com/xdb"
version="1.0"
xdb:storeVarrayAsTable="true">
<xs:element name="PurchaseOrder" type="PurchaseOrderType" xdb:defaultTable="PURCHASEORDER"/>
<xs:complexType name="PurchaseOrderType" xdb:SQLType="PURCHASEORDER_T">
<xs:sequence>
<xs:element name="ORG_ID" type="IdType" minOccurs="0" xdb:SQLName="ORG_ID"/>
and the xml file would be:
<PurchaseOrder xsi:noNamespaceSchemaLocation="PurchaseOrders.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
     <ORG_ID>204</ORG_ID>
... etc.
This system works fine - but the dequeue procedure, which is called before the xml is inserted into the XMLType table does not have a way to determine what kind of XML file this is. So basically, the path will be different for each different type of file.
Is there a easy way to either:
- get the FILETYPE variable some other way using PL/SQL when the initial path would be different for each file type?
- OR define the schema in such a way that allows for that information to be in the same "path"
I was thinking of something along the lines of ...
a) using remarks (how would we be able to read it using simple PL/SQL?)
b) or maybe just defining a simple type as the initial element - kind of like this:
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:xdb="http://xmlns.oracle.com/xdb"
version="1.0"
xdb:storeVarrayAsTable="true">
<xs:element name="FILETYPE" type="String_240Type" xdb:SQLName="FILETYPE"/>
<xs:element name="PurchaseOrder" type="PurchaseOrderType" xdb:defaultTable="PURCHASEORDER"/>
<xs:complexType name="PurchaseOrderType" xdb:SQLType="PURCHASEORDER_T">
<xs:sequence>
<xs:element name="ORG_ID" type="IdType" minOccurs="0" xdb:SQLName="ORG_ID"/>
with a corresponding xml of:
<FILETYPE xsi:noNamespaceSchemaLocation="PurchaseOrders.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">PO</FILETYPE>
<PurchaseOrder>
     <ORG_ID>204</ORG_ID>
(but XMLSpy assures me this is not valid - neither the xchema nor the xml)
Any help would be deeply appreciated!
Thanks!
Edited by: user11313400 on Aug 17, 2009 11:17 AM
Edited by: user11313400 on Aug 17, 2009 11:20 AM

Answer 1

I don't fully understand all the issues behind your questions but I'll give some answers. What is wrong with your current code of
v_filetype := message.extract('//FILETYPE/text()').getStringVal();in retrieving the FILETYPE? While the use of // is not the best for performance, that will find FILETYPE where ever it resides in the message XML? If you know FILETYPE resides at a certain level, you could also do the following to improve performance a bit (untested theory)
v_filetype := message.extract('/*/FILETYPE/text()').getStringVal();
That sample assumes FILETYPE is a child of the root node, and doesn't care what the root node is named.
As you are going to, the best method would be to have FILETYPE is the same location for all the XML messages to make retrieval the easiest. Without a larger sample of your .xsd I won't offer a working solution, but can you just make FILETYPE part of the PurchaseOrderType definition? I know you mentioned multiple XML file types so I'm not sure what the others look like and what you can and cannot change.
Other thoughts:
- Could you pass in the file type as part of what is enqueued in AQ?
- Can you determine file type from the name of the root node in the XML?