QTrouper

Do raindrops follow a certain hierarchy when they fall?

• by Anthony T. Hincks

Maven Dependency

Use the following repository:

<repository>
    <id>clojars</id>
    <name>Clojars repository</name>
    <url>https://clojars.org/repo</url>
</repository>

Use the following maven dependency:

<dependency>
    <groupId>io.github.qtrouper</groupId>
    <artifactId>qtrouper</artifactId>
    <version>0.0.1-1</version>
</dependency>

Build instructions

• Clone the source:

  git clone github.com/koushikr/qtrouper
  

• Build

  mvn install
  

QTrouper provides the following capabilities

• Create a hierarchy of retry and sideline for queue
• Configure the number of times and the backoff on the retry queue
• Enable consumption on the sideline queue or otherwise.
• Queue the entire context with intermediate objects, so long as they are serializable.
• An interface for consumption of main queue and sideline queue messages

Key Concepts

• Main Queue : A queue on which the primary action is performed. Define a consumer on this queue by extending the Trouper class and implementing its process method.
• Retry Queue : A retry queue is not visible to the user. It is responsible for expiring a message and dead lettering into main queue till the maxRetryCount is not breached.
• Sideline Queue : A sideline queue on which the tertiary action is performed. Define a consumer on this queue by extending the Trouper class and implementing its processSideline method
• QueueContex : A Map to a key + a serializable object that gets enqueued in the queues
• Trouper : The Trouper is the queueing interface to provide main_queue, retry_queue and sideline_queue implementations for any call to action.

The overriding design goal for qtrouper model is to make it as ready as possible to onboard a new message processor. The idea is that a formatted consumer definition is usable as-is, as a processing unit inside the app, without having to create any additiional boiler plate code to support the same. And a dropwizard bundle is made out of it for easy integration with dropwizard apps.

Tech

QTrouper uses rabbitMQ as its backend interface and the

• Dropwizard - The bundle that got created
• RabbitMQ - Messaging that just works.

Example

Sample Configuration

static class SampleConfiguration extends Configuration{

        private RabbitConfiguration rabbitConfiguration;

    }
}

Bundle Inclusion

      TrouperBundle<SampleConfiguration> trouperBundle = new TrouperBundle<SampleConfiguration>() {

                @Override
                public RabbitConfiguration getRabbitConfiguration(SampleConfiguration configuration) {
                    return null;
                }
      };

      bootstrap.addBundle(trouperBundle);

Sample Actor

static class QueueingActor extends QTrouper<QueueContext> {

        @Inject
        public SymphonyActor(QueueConfiguration consumerConfiguration, RabbitConnection rabbitConnection) {
            super("sampleQueue",
                    consumerConfiguration,
                    rabbitConnection,
                    QueueContext.class,
                    Collections.emptySet());
        }

        @Override
        protected boolean process(QueueContext queueContext, QAccessInfo accessInfo){
            try{
                return processor.consume(queueContext, accessInfo);
            }catch (Exception e){
                log.error("Error processing a main queue message for reference Id {}", queueContext.getServiceReference());
                return false;
            }
        }

        @Override
        protected boolean processSideline(QueueContext queueContext, QAccessInfo accessInfo) {
            try{
                return processor.consumeSideline(queueContext, accessInfo);
            }catch (Exception e){
                log.error("Error processing a sideline queue message for reference Id {}", queueContext.getServiceReference());
                return false;
            }
        }
    }

LICENSE

Copyright 2019 Koushik R rkoushik.14@gmail.com.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.