Problem with Oracle8 Blobs

[baillieul]

I have set up an Oracle8 datasource by modifying an existing Hypersonic configuration. My entity EJBs retrieve data fine from most tables until I hit a BLOB column, in which I get:

2002-08-26 21:02:36,520 DEBUG [com.zaplet.server.process.ProcessBean] setEntityContext
2002-08-26 21:02:36,520 DEBUG [com.zaplet.server.process.ProcessBean] ejbActivate
2002-08-26 21:02:36,520 DEBUG [org.jboss.ejb.plugins.cmp.jdbc.JDBCLoadEntityCommand.Process] Executing SQL: SELECT VERSION, DEFINITIONID, NAME, TITLE, CREATORID, OWNERID, CREATEDDATE, MODIFIERID, MODIFIEDDATE, STARTEDDATE, COMPLETEDDATE, STATE, SECURITYLEVEL, DATA FROM PROCESS WHERE (PROCESSID=?)
2002-08-26 21:02:36,560 ERROR [org.jboss.ejb.plugins.LogInterceptor] TransactionRolledbackLocalException, causedBy:
java.sql.SQLException: Unable to load to deserialize result: java.io.StreamCorruptedException: invalid stream header
at org.jboss.ejb.plugins.cmp.jdbc.JDBCUtil.convertByteArrayToObject(JDBCUtil.java:612)
at org.jboss.ejb.plugins.cmp.jdbc.JDBCUtil.getResult(JDBCUtil.java:311)
at org.jboss.ejb.plugins.cmp.jdbc.bridge.JDBCAbstractCMPFieldBridge.loadArgumentResults(JDBCAbstractCMPFieldBridge.java:350)
at org.jboss.ejb.plugins.cmp.jdbc.bridge.JDBCAbstractCMPFieldBridge.loadInstanceResults(JDBCAbstractCMPFieldBridge.java:304)
at org.jboss.ejb.plugins.cmp.jdbc.JDBCLoadEntityCommand.execute(JDBCLoadEntityCommand.java:142)
at org.jboss.ejb.plugins.cmp.jdbc.JDBCLoadEntityCommand.execute(JDBCLoadEntityCommand.java:62)
at org.jboss.ejb.plugins.cmp.jdbc.JDBCStoreManager.loadEntity(JDBCStoreManager.java:572)


The process table contains a BLOB. I have fiddled with the standardjaws.xml file to try to get around this error, but have had no luck. Ideas????

[davidjencks]

This is a very popular question, but I don't know the answer. I'd search the cmp forum and both mailing lists. My understanding is the basically the Oracle drivers don't work, and working around their limitations is difficult.

[stevewink]

There are problems with Oracle 8 JDBC drivers and LOBs, and you have to write Oracle specific code to use them. So much for standards...
Apparently Oracle 9 has fixed this but I haven't used it for LOBs personally.

[baillieul]

I have reied to make Jboss/Oracle blobs work with Oracle8 and 9. No workie. The OCI drivers apparently do not work with JBOSS at all. Tried tweaking the standardjbosscmp-jdbc file to get away from Blobs, but no luck. Also tried JBoss versions 3.0.0 , 3.0.1 and 3.0.2 . Any ideas????

[davidjencks]

As I said before, ask on the cmp forum. As far as datasource configuration is concerned, they work fine.

It may be possible to write an oracle specific jca-jdbc wrapper extending the appropriate existing wrapper classes to work around the laughing-at-the-spec behaviour of the oracle drivers, but first you need to find out how to work around them.

[stevewink]

If anyone wants Oracle/LOB information:
( you may need an OTN logon to see some of the pages on the oracle web site. )

http://otn.oracle.com/tech/java/sqlj_jdbc/pdf/a96654.pdf ( for Oracle 9 )

http://technet.oracle.com/doc/oracle8i_816/java.816/a81354/oralob2.htm#1057908 ( has Oracle 8 stuff )

http://www.oracle.com/forums/message.jsp?id=664650

There should also be sample code in your Oracle installation.

I don't know about CMP, but if you are just getting drivers or data sources from JBoss to use as normal JDBC, you can use the current jca-jdbc wrapper, as the Blob code should be in your client code.

[gzzz]

To avoid problems I changed the standardjaws.xml in


<java-type>java.lang.Object</java-type>
<jdbc-type>BLOB</jdbc-type>
<sql-type>BLOB</sql-type>
<!-- Change this from BLOB to RAW(255) if you know your
serialized object will be <= 255 bytes -->