[jboss-user] [JBoss Messaging] - Re: Messaging Persistence and Multiple JBoss Instances

[rtm333]

Tim,

Thanks for your reply. 

Actually, we do not give any unique ids to the server instances. Where and how could this be done?

To clarify, I'm not talking about some form of clustering. We are using several independent "instances" of JBoss, that are mapped to different ports by the ServiceBindingManager. The instances share a common Sybase database for persisting JMS messages.

In the meantime we have explored this issue in two directions:

1. Using an instance specific sybase-persistence-service.xml, that adds a server id column to all JMS persistence tables and uses a (hard-coded) server id in all SQL statements for selections/updates. 

2. Usage of Apache Derby: This creates an individual copy of the persistence database in each instance's data directory. There are two problems with this approach:

a) JDBC type LONGVARBINARY (used for storing message content) is not compatible to Derby type BLOB, but only to "LONG VARCHAR FOR BIT DATA" with a maximum length of 32700 bytes. 

b) In method org.jboss.messaging.core.plugin.JDBCPersistenceManager.getBytes(ResultSet rs, int columnIndex) the method rs.getBinaryStream() is invoked twice on the same column (line 4250). This is considered an error by Derby. Workaround: change the second usage to use the first result (i), recompile and use the generated jboss-messaging.jar in jboss-messaging.sar. 

// is = new BufferedInputStream(rs.getBinaryStream(columnIndex), BUFFER_SIZE);
is = new BufferedInputStream(i, BUFFER_SIZE);

Both solutions seem to work (in Derby's case with the limitation that messages longer than about 32k cannot be stored).



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