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From jcllings <jclli...@gmail.com>
Subject Re: Running Cassandra Server in an OSGi container
Date Tue, 22 Jul 2014 21:39:35 GMT
I can give you some tips.

Figure out what Cassandra does when it starts up. Best way to do that is
to read the startup script.  Then all you have to do is convince the
OSGI container to do what ever prep is done by the script.  Trick to
that is usually figuring out where to do it. For example if there are
environment variables set in the script for Cassandra, you should add
them to the script for your OSGI container.  If there are any -D
options, you would have to use what ever mechanism your OSGI container
uses to pass them.  There might be a properties file for example or
there might be actual -D settings, depending.  You should probably make
your best guess as to where to put the configuration files but watch the
logs for errors to this effect, e.g. "ERROR: Doh! Can't find the config
dir / file / etc."  Of course, if the Cassandra libs aren't OSGI-ified
you would have to do that also.

Jim C.

On 07/22/2014 01:19 PM, Robert Stupp wrote:
> What's your intention to do this?
>
> There are unit test integrations using C* daemon. A related bug that
> prevented proper shutdown has been closed for C*
> 2.1-rc1: https://issues.apache.org/jira/browse/CASSANDRA-5635
> It's perfectly fine to embed C* for unit tests.
>
> But I'd definitely not recommend to use C* within a container in a
> real production environment.
> Not just because of the few System.exit calls in CassandraDaemon but
> also of the other places where System.exit is called for very good
> reasons. These reasons include system/node failure scenarios (for
> example disk failures).
>
> C* is designed to run in its own JVM process using dedicated hardware
> resources on multiple servers using commodity hardware without any
> virtualization or any shared storage. And it just works great with that.
>
> There are good reasons to move computation near to the data - but
> that's always a separate OS process on C* nodes. Examples are Hadoop
> and Spark.
>
> Am 22.07.2014 um 21:45 schrieb Rodgers, Hugh <hugh.rodgers@lmco.com
> <mailto:hugh.rodgers@lmco.com>>:
>
>> Hello –
>>  
>> I have a use case where I need to run the Cassandra Server as an OSGi
>> bundle. I have been able to embed all of the Cassandra dependencies
>> in an OSGi bundle and run it on Karaf container, but I am not happy
>> with the approach I have thus far.
>>  
>> Since CassandraDaemon has System.exit() calls in it, if these execute
>> it will bring down my entire OSGi container rather than just the
>> bundle Cassandra is running in. I hacked up a copy of CassandraDaemon
>> enough to get it to run in the bundle with no System.exit() calls,
>> but the Cassandra StorageService is not “aware” of it, i.e., I cannot
>> call the StorageService.registerDaemon(…) method because my copy of
>> CassandraDaemon does not extend Apache’s. hence I am getting
>> exceptions when I do shutdown my container or restart the bundle
>> because the StorageService and my CassandraDaemon are not “linked”.
>>  
>> I am considering trying to extend Apache’s CassandraDaemon and
>> override its setup() method with a SecurityManager that disables
>> System.exit() calls. This too sounds “hacky”.
>>  
>> Does anyone have any better suggestions? Or know of an existing open
>> source project that has successfully embedded CassandraServer in an
>> OSGi bundle?
>>  
>> I am using Cassandra v2.0.7 and am currently using CQL (vs. Thrift).
>>  
>> Thanks –
>>  
>> Hugh
>


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