ElasticMQ – the SQS power available locally

Amazon Simple Queue Service (Amazon SQS) is a distributed message queuing service. It is similar to other well-known messaging solutions like RabbitMQ, ActiveMQ, etc. but it is hosted by Amazon.
It is a really fast, configurable and relatively simple messaging solution.

In my current company we strongly rely on the AWS infrastructure. One major Amazon cloud component we use is the SQS (Simple Queue Service).
It allows us to decouple components in the application. We also send lots of notification through SQS which makes handling them reliable.

In short words, SQS works perfectly for us. The only issue we had was running the application in development mode which means running it locally without the need to integrate with the AWS infrastructure. The same problem arises in the integration tests.
The best solution would be to have the SQS running locally or even better have the service that can be embedded into the application.

And here Adam Warski and his ElasticMQ comes to the rescue.
ElasticMQ is a message queue system that can be run either stand-alone or embedded.
It has Amazon-SQS compatible interface which means implementing some of the SQS query API
(I am not sure if the full API is implemented but all the standard queries are there).

As already mentioned, ElasticMQ can be run in two ways:

1. Stand-alone service

It is as simple as running the command:

java -Dconfig.file=custom.conf -jar elasticmq-server-0.10.0.jar

Then the application needs to be configured with the proper SQS url, for example:



2. Embedded mode

This mode is perfect for integrating the ElasticMQ into the application running on the developer’s station or run it during the integration tests.

First step is to setup the ElasticMQ server. We use Play 2.4 and Guice as the dependency injection framework.
In order to start the ElasticMQ when the application starts I simply extend Guice AbstractModule:

import com.google.inject.AbstractModule
class StartupModule extends AbstractModule {
   override def configure() = {

The launcher itself starts the ElasticMQ server:

val config = ConfigFactory.load()
val server = new ElasticMQServer(new ElasticMQServerConfig(config))
val shutdown = server.start()

Having the ElasticMQ server running that way and changing only the SQS queue url in application properties we can run the infrastructure depending on the SQS locally without need to communicate with the SQS cloud service.