I mentioned in the article on SaaS offering of ITIL, that the cloud computing or as SaaS matures, more infrastructure software components would be made available in the cloud. For example on demand Message Queuing (MQ) service.
In house MQ software has played an important role in the enterprise application integration world for over a decade. However in the integration of services in the Web 2.0 world, the traditional message queuing model has some limitations such as:
1. Lack of accessing MQ over HTTP(S) protocol straight out of box. In order to accomplish this, service providers had to build HTTP(S) Adapters over MQ.
2. Scalability issues arise, when integrating over HTTP(S,) because of a lack of MQ platform agnostic and proven implementation of HTTP(S) Adapters.
3. Additional costs to cover licensing and server provisioning when service demand increases.
4. Troubleshooting requires a deep understanding of the MQ product. Obviously highly skilled MQ admin personnel don’t come cheap.
5. Full life cycle management of MQ environment has a cost associated to it and is directly proportional to the number of integrations and the number of messages processed.
6. Web 2.0 companies are interested in focusing on their core offering as opposed to managing integration infrastructure and challenges associated with it.
The above limitations make sense to use MQ service on demand. Some examples of such service providers are:
1. Amazon Simple Queue Service (SQS)
2. Gnip
3. OnlineMQ
SQS is a basic queuing service provided by Amazon in EC2 cloud computing platform. One of the advantages of SQS is in guaranteed availability of messages when dropped on the SQS queues. Second, if your service is hosted on EC2 then using SQS is cost saving because intra EC2 data communication is free of charge. However publish and subscribe style of messaging is not yet offered. Neither does it offer guaranteed once and only once of message delivery. One has to programmatically control that the same message is not delivered multiple times.
Gnip (see our coverage here) has a success story on offloading traffic from high volume web sites such as Digg, Twitter among others. Gnip uses Amazon’s SQS and wraps the access to it based on SEDA; probably this is the reason why they can handle high message volume. Gnip provides more than a traditional MQ, for example they also provide services such as message transformation and routing. You can use Gnip if you are integrating with any of the sender or receiver from the list of supported consumers/producers of Gnip. Any custom integration or integration between your application components would find Gnip limited.
OnlineMQ is a new service and still in beta. However they seem to be providing a comprehensive MQ service. OnlineMQ provides an intuitive GUI based admin tool and supports both styles of messaging i.e. PTP and Pub/Sub models. You can enable or disable a queue for read only or write only.
From the above solutions none of them is an ideal MQ solution for all situations. However choosing Amazon’s SQS provides you with the flexibility of building the functionality that you need over it.
If you liked this article, then you may find the below mentioned cloud computing and SaaS articles interesting: