OSB - Iterating over large XML files with content streaming

Question

Hi @ll
I have to iterate over all item in large XML files and insert into a oracle database.
The file is about 200 MB and contains around 500'000, and I am using OSB 10gR3.
The XML structure is something like this:
<allItems>
<item>.....</item>
<item>.....</item>
<item>.....</item>
<item>.....</item>
<item>.....</item>
</allItems>
Actually I thought about using a proxy service with enabled content streaming and a "for each" action for iterating
over all items. But for this the whole XML structure has to be materialized into a variable otherwise it is not possible!
More about streaming large files can be found here:
[http://download.oracle.com/docs/cd/E13159_01/osb/docs10gr3/userguide/context.html#large_messages]
There is written "When you enable streaming for large message processing, you cannot use the ... for each...".
And for accessing single items you should should use an assign action with a xpath like "$body/allItems/item[1]";
this works fine and not the whole XML stream has to be materialized.
So my idea was to use the "for each" action and processing seqeuntially all items with a xpath like:
$body/allItems/item[$counter]
But the "for each" action just allows iterating over a sequence of xml items by defining an selection xpath
and the variable that contains all items. I would like to have a "repeat until" construct that iterates as long
$body/allItems/item[$counter] returns not null. Or can I use the "for each" action differently?
Does the OSB provides any other iterating mechanism? I know there is this spli-join construct that supports
different looping techniques, but as far I know it does not support content streaming, is this correct?
Did I miss somehting?
Thanks a lot for helping!
Cheers
Dani
Edited by: user10095731 on 29.07.2009 06:41

Answer 1

Hi Dani,
Yes, according to me this would be the best approach. You can use content-streaming to pass this large xml to ejb and once it passes successfully EJB should operate on this. If you want any result back (for further routing), you can get it back from EJB.
EJB gives you power of java to process this file and from java perspective 150 MB is not a very LARGE data. Ensure that you are using buffering. Check out this link for an explanation on Java IO Streams and, in particular, buffered streams -
http://java.sun.com/developer/technicalArticles/Streams/ProgIOStreams/
Try dom4J with xpp (XML Pull Parser) parser in case you have parsing requirement. We had worked with 1.2GB file using this technique.
Regards,
Anuj