[rabbitmq-discuss] ANN New project QDB: Persistent Message Queues With Replay

Tom Anderson tom.anderson at timgroup.com
Thu Aug 1 13:00:37 BST 2013

On 01/08/13 11:44, David Tinker wrote:
> QDB provides persistent message queues with the ability to efficiently
> replay old messages by timestamp or id. It can push messages from its
> queues directly to RabbitMQ and has simple REST interface.
> http://qdb.io/

Interesting. Thanks!

Can you feed it from RabbitMQ too? If not, any plans to make that 
possible? A replayable recent history of certain queues could be 
insanely useful for us. If not, it looks like it wouldn't be that hard 
for us to add if we wanted it.

A few minor remarks:

- "QDB depends on two libraries that are not yet on Maven central ... 
These need to be built and installed in your local Maven repository 
before building QDB." - have you considered putting artifacts for these 
up in a non-Central repository? I do that via a repo hosted on my 
Bitbucket site - see https://bitbucket.org/twic/twic.bitbucket.org/src 
and https://bitbucket.org/twic/twic.bitbucket.org/src/default/release.sh 
for the script that updates it - and find it fairly easy. I think this 
is even easier on GitHub.

- Building and installing locally is rendered less than entirely smooth 
by (a) the fact that both projects use the signing plugin, which means i 
would have to set up GPG etc just to install locally (i commented out 
the signing declarations instead), (b) qdb-kvstore refers to a repo with 
url "/Users/david/.m2/repository", (c) qdb-kvstore depends on version 
0.4.0-SNAPSHOT of qdb-buffer, but if you check out and build qdb-buffer, 
you make version 0.4.1-SNAPSHOT.

- The qdb-server build at revision c5c7ac3b7a11 has one failing test, 
because this:

     def "Format timestamp works"() {
         Date d = new 
         String s = DateTimeParser.INSTANCE.formatTimestamp(d)

         s == "2013-06-16T21:04:32.123+0200"

Won't pass if you don't live in South Africa, or somewhere else with a 
+0200 timezone.

And some handwaving:

- If you ever fancy using a different storage engine, you might be 
interested in http://www.mapdb.org/ . Not sure if it has the event 
notification, though, nor if its performance characteristics are really 
what you need.

- For qdb-buffer, it might be helpful to write a comparison between what 
seems like your main use case (buffering messages heading towards 
RabbitMQ to protect against RabbitMQ doing down) and running a local 
RabbitMQ on every box as a first hop.



Tom Anderson | Developer | +44 20 7826 4312 | timgroup.com 

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