Oracle Coherence: Coherence within the Oracle Ecosystem

If you look at Oracle marketing material, you will find out that Coherence is a member of the Oracle Fusion Middleware product suite. However, if you dig a bit deeper, you will find out that it is not just another product in the suite, but a foundation for some of the high-profile initiatives that have been announced by Oracle, such as Oracle WebLogic Application Grid and Complex Event Processing.

Coherence is also the underpinning of the "SOA grid"—a next-generation SOA platform that David Chappell, vice president and chief technologist for SOA at Oracle, wrote about for The SOA Magazine [SOAGrid1&2].

I believe that over the next few years, we will see Coherence being used more and more as an enabling technology within various Oracle products, because it provides an excellent foundation for fast, scalable, and highly-available solutions.

Coherence usage scenarios

There are many possible uses for Coherence, some more conventional than the others.

It is commonly used as a mechanism to off-load expensive, difficult-to-scale backend systems, such as databases and mainframes. By fronting these systems with Coherence, you can significantly improve performance and reduce the cost of data access.

Another common usage scenario is eXtreme Transaction Processing (XTP). Because of the way Coherence partitions data across the cluster, you can easily achieve throughput of several thousand transactions per second. What's even better is that you can scale the system to support an increasing load by simply adding new nodes to the cluster. As it stores all the data in memory and allows you to process it in-place and in parallel, Coherence can also be used as a computational grid. In one such application, a customer was able to reduce the time it took to perform risk calculation from eighteen hours to twenty minutes.

Coherence is also a great integration platform. It allows you to load data from multiple data sources (including databases, mainframes, web services, ERP, CRM, DMS, or any other enterprise system), providing a uniform data access interface to client applications at the same time.

Finally, it is an excellent foundation for applications using the Event Driven Architecture, and can be easily integrated with messaging, ESB, and Complex Event Processing (CEP) systems.

That said, for the remainder of the book I will use the "conventional" web application architecture described earlier, to illustrate Coherence features—primarily because most developers are already familiar with it and also because it will make the text much easier to follow.