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From Andrew Lawrenson <andrew.lawren...@coppereye.com>
Subject RE: Derby Encryption AND Replication
Date Tue, 30 Sep 2008 13:19:27 GMT

        I've possibly found where the problem is being caused.  (This is with v

When booting my slave database, a nullpointer exception is being thrown whilst trying to decrypt

Exception in thread "derby.slave.boot-DRS-H3G" java.lang.NullPointerException
        at org.apache.derby.impl.store.raw.log.LogToFile.decrypt(LogToFile.java:4327)
        at org.apache.derby.impl.store.raw.log.Scan.getNextRecordForward(Scan.java:844)
        at org.apache.derby.impl.store.raw.log.Scan.getNextRecord(Scan.java:206)
        at org.apache.derby.impl.store.raw.log.LogToFile.initializeReplicationSlaveRole(LogToFile.java:5228)
        at org.apache.derby.impl.store.replication.slave.SlaveController.startSlave(SlaveController.java:232)
        at org.apache.derby.impl.store.raw.RawStore.boot(RawStore.java:328)
        at org.apache.derby.impl.services.monitor.BaseMonitor.boot(BaseMonitor.java:2019)
        at org.apache.derby.impl.services.monitor.TopService.bootModule(TopService.java:291)
        at org.apache.derby.impl.services.monitor.BaseMonitor.startModule(BaseMonitor.java:573)
        at org.apache.derby.iapi.services.monitor.Monitor.bootServiceModule(Monitor.java:427)
        at org.apache.derby.impl.store.access.RAMAccessManager.boot(RAMAccessManager.java:1019)
        at org.apache.derby.impl.services.monitor.BaseMonitor.boot(BaseMonitor.java:2019)
        at org.apache.derby.impl.services.monitor.TopService.bootModule(TopService.java:291)
        at org.apache.derby.impl.services.monitor.BaseMonitor.startModule(BaseMonitor.java:573)
        at org.apache.derby.iapi.services.monitor.Monitor.bootServiceModule(Monitor.java:427)
        at org.apache.derby.impl.db.BasicDatabase.bootStore(BasicDatabase.java:780)
        at org.apache.derby.impl.db.BasicDatabase.boot(BasicDatabase.java:196)
        at org.apache.derby.impl.db.SlaveDatabase.bootBasicDatabase(SlaveDatabase.java:424)
        at org.apache.derby.impl.db.SlaveDatabase.access$000(SlaveDatabase.java:70)
        at org.apache.derby.impl.db.SlaveDatabase$SlaveDatabaseBootThread.run(SlaveDatabase.java:311)
        at java.lang.Thread.run(Thread.java:619)

As I see it, when you call SlaveController.startSlave(), you pass in a LogFactory object (which
is actually a LogToFile object).
This LogToFile object needs its "rawStoreFactory" object set before it can call decrypt()
which is called as above - and this rawStoreFactory object is only set during a call to LogToFile.recover().

However, in RawStore.boot(), where the LogFactory is created, LogFactory.recover() is only
called _after_ SlaveController.startSlave():

      // If SlaveFactory is to be booted, the boot has to happen
      // before logFactory.recover since that method will be blocked
      // when in replication slave mode.
        if (inReplicationSlaveMode) {
            // The LogFactory has already been booted in slave mode.
            // Can now start slave replication by booting the
            // SlaveFactory service
            slaveFactory = (SlaveFactory)
                Monitor.bootServiceModule(create, this,
        slaveFactory.startSlave(this, logFactory);

        // no need to tell log factory which raw store factory it belongs to
        // since this is passed into the log factory for recovery
        // after the factories are loaded, recover the database
        logFactory.recover(this, dataFactory, xactFactory);

The comments here imply the order has to be this way round - however, it seems to be this
ordering which is causing the problem in my case.

At this point, I'm starting to feel quite out of my depth - does this make sense to you?

Thanks again,


-----Original Message-----
From: Andrew Lawrenson [mailto:andrew.lawrenson@coppereye.com]
Sent: 30 September 2008 10:29
To: Derby Discussion
Subject: RE: Derby Encryption AND Replication


        thanks for your clarification regarding the status of this combination of features.

        I think my issue is something more than just waiting for the master to connect, as:

1) once the slave gets in it's "hanging" state, it is not listening on the slave port, as
checked via netstat.

If I'm using a non-encrypted database, it works fine and is listening ok:
-bash-3.00$ netstat -a | grep 6959
myserver.6959              *.*                0      0 49152      0 LISTEN

2) when the master tries to connect to it, it gets a connection refused:

Caused by: ERROR XRE04: Could not establish a connection to the peer of the replicated database
'DRS-H3G' on address 'myserver.boxhouse.indigo-one.com:6959'.
        at org.apache.derby.iapi.error.StandardException.newException(Unknown Source)
        at org.apache.derby.impl.store.replication.master.MasterController.setupConnection(Unknown
        at org.apache.derby.impl.store.replication.master.MasterController.startMaster(Unknown
        at org.apache.derby.impl.store.raw.RawStore.startReplicationMaster(Unknown Source)
        at org.apache.derby.impl.store.access.RAMAccessManager.startReplicationMaster(Unknown
        ... 16 more
Caused by: java.security.PrivilegedActionException: java.net.ConnectException: Connection
        at java.security.AccessController.doPrivileged(Native Method)
        at org.apache.derby.impl.store.replication.net.ReplicationMessageTransmit.initConnection(Unknown
        ... 20 more
Caused by: java.net.ConnectException: Connection refused
        at java.net.PlainSocketImpl.socketConnect(Native Method)
        at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)
        at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
        at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
        at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
        at java.net.Socket.connect(Socket.java:519)
        at org.apache.derby.impl.store.replication.net.ReplicationMessageTransmit$1.run(Unknown
        ... 22 more

Whereas this works fine with a non-encrypted database.

I'll continue digging, and try to find out what is going on...

Thanks again,


-----Original Message-----
From: Jorgen.Loland@Sun.COM [mailto:Jorgen.Loland@Sun.COM]
Sent: 30 September 2008 10:01
To: Derby Discussion
Subject: Re: Derby Encryption AND Replication

Hi Andrew,

The reason why encryption and replication is not documented is because it has not been tested
at all. Theoretically, there is nothing I can think of that will prevent it from working [1].
On the other hand, we may have forgotten some details that I expect to be easy fixes if somebody

The hang you get on the slave is expected. When you boot a database in slave mode, the connection
attempt is designed to hang until the master connects to it. For details, take a look at this
page in the Derby Server and Admin guide:


I have created an encrypted database and tried the connection string you suggested [2]. I
successfully set up replication, and did some simple DML and DDL operations on the master.
The operations were correctly reflected on the slave after failover, as expected.

* It does work in theory
* A simple test confirmed that it works
* This combination of features has not been tested thoroughly.
* We may have forgotten some corner cases that needs to be fixed

* I can not guarantee correct results, although I am pretty sure it will work.

[1] Replication works by sending the (recovery) log records from the master to the slave.
The log records store physical changes to disk blocks, and in encrypted mode these changes
are encrypted as well.
Replication has a lot in common with Derby's Online Backup feature which
*does* support encryption.

1. Master: connect
3. Slave: connect
4. Master: connect
5. Master: do some test DDL and DML operations
6: Master: connect 'jdbc:derby:enctest2;failover=true';
7: Slave: connect
8. Slave: ensure results are as expected

Hope this helps,
Jørgen Løland

Andrew Lawrenson wrote:
> Hi All,
>     is it possible to use replication to replicate an encrypted database.  Various things
hint that it isn't supported (such as the StartSlave attribute not specifying that you can
combine it with encryptionKey), but I can't find anything explicitly saying it isn't supported.
>     If I boot the slave database without the encryption key, I get an exception with
SQLState XBM06, as expected.  If I pass in the encryption details as well, so my connection
attributes contains the following: "startSlave=true;slaveHost=;slavePort=6959;encryptionAlgorithm=DES/CBC/NoPadding;encryptionKey=aaaaaaaabbbbbbbb"
then derby hangs indefinately whilst booting:
>    java.lang.Thread.sleep(Native Method)
>    org.apache.derby.impl.db.SlaveDatabase.verifySuccessfulBoot(Unknown Source)
>    org.apache.derby.impl.db.SlaveDatabase.boot(Unknown Source)
>    org.apache.derby.impl.services.monitor.BaseMonitor.boot(Unknown Source)
>    org.apache.derby.impl.services.monitor.TopService.bootModule(Unknown Source)
>    org.apache.derby.impl.services.monitor.BaseMonitor.bootService(Unknown Source)
>    org.apache.derby.impl.services.monitor.BaseMonitor.startProviderService(Unknown Source)
>    org.apache.derby.impl.services.monitor.BaseMonitor.findProviderAndStartService(Unknown
>    org.apache.derby.impl.services.monitor.BaseMonitor.startPersistentService(Unknown
>    org.apache.derby.iapi.services.monitor.Monitor.startPersistentService(Unknown Source)
>    org.apache.derby.impl.jdbc.EmbedConnection.bootDatabase(Unknown Source)
>    org.apache.derby.impl.jdbc.EmbedConnection.<init>(Unknown Source)
>    org.apache.derby.impl.jdbc.EmbedConnection30.<init>(Unknown Source)
>    org.apache.derby.impl.jdbc.EmbedConnection40.<init>(Unknown Source)
>    org.apache.derby.jdbc.Driver40.getNewEmbedConnection(Unknown Source)
>    org.apache.derby.jdbc.InternalDriver.connect(Unknown Source)
>    org.apache.derby.jdbc.AutoloadedDriver.connect(Unknown Source)
>    java.sql.DriverManager.getConnection(DriverManager.java:582)
>    java.sql.DriverManager.getConnection(DriverManager.java:185)
> Is it possible for anyone to confirm if this should be supported or not?
> many thanks,
>   Andrew Lawrenson

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