Well my case is a little different as the locking or synchronization is
not per object.
In my case it was the connection to a backend system (a Stock Exchange)
where only one instance should be connected to the
exchange but several were needed as fallbacks.
So the main difference is that in my case the producer of the route had
to be enabled / disabled instead of a processing step inside the route.
Still many aspects are common and I can imagine that hazelcast would
also work for me.
Christian
Am 07.09.2011 18:10, schrieb boday:
Christian, my use case is that I have multiple apps that update the same data
(PurchaseOrders) and we periodically see some stale writes. We have a
combination of Camel/CXF web services (load balanced across 2 machines) and
batch processing in Camel routes (in a separate app) and are evaluating
using Hazelcast distributed locking to make sure only one thread works on a
PO at any given time.
Its simple enough to just manually add the Hazelcast locking in as pre/post
processors in routes, it just got me thinking about how it could fit into
Camel natively (since we already have a Hazelcast component, etc). As
suggested by others, maybe the term "lock" is confusing and we should term
it "synchronized" or "exclusive" or something...
Christian Schneider wrote:
I am not sure if this is the same use case that I had some years ago.
We wanted to have several instances of an integration running but only
one of them should be active at any time.
At the time there was no easy solution for this problem.
So in that use case you would have several instances of camel each on
its own machine.
They could have the same route but only one should be active.
In the dsl this could also be expressed with a lock or perhaps exclusive
element.
from("some source ").exclusive("some id")....
So the question in this case is: What lib or backend would be suitable
to impement this and what parameters would we need?
Does Hazelcast support this scenario?
Would we start and stop the route when it gets or looses the lock?
Christian
Am 06.09.2011 22:16, schrieb boday:
hey guys, while working on a solution for a client, I ran into the need
to
"synchronize" multiple routes that modify the same data (users, orders,
etc)
to prevent collisions (stale writes, etc). Is there an existing way to
do
this that I've overlooked?
In the past, I've relied on
http://activemq.apache.org/message-groups.html
AMQ message groups for JMS based routes and Hazelcast to span
routes/containers. I feel this would be a good fit for the Camel DSL.
Has
anyone looked into this in the past?
After doing some quick research, it seems like Java
http://download.oracle.com/javase/6/docs/api/java/util/concurrent/locks/Lock.html
Lock seems to be the way to go. Also, Hazelcast can extend this to be
distributed across VMs.
So, I've been playing around with adding distributed locking support with
Hazelcast (see https://issues.apache.org/jira/browse/CAMEL-4397
CAMEL-4397
) and wanted to get some feedback on doing this. In particular, I'm
using a
Lock instance stored in a ThreadLocal variable (to ensure that the same
thread releases the lock). Does anyone see any issue with this approach?
If all goes well with this, I was planning on also adding a DSL API to
provide a basic support for (non distributed)
http://download.oracle.com/javase/6/docs/api/java/util/concurrent/locks/ReentrantLock.html
ReentrantLocks .
something like this...
from(route1).lock(userId).process(processor1).unlock();
from(route2).lock(userId).process(processor2).unlock();
Any advice/comments are welcome...thanks
-----
Ben O'Day
IT Consultant -http://consulting-notes.com
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--
Christian Schneider
http://www.liquid-reality.de
Open Source Architect
http://www.talend.com
-----
Ben O'Day
IT Consultant -http://consulting-notes.com
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Christian Schneider
http://www.liquid-reality.de
Open Source Architect
http://www.talend.com
