Grid-Enabled SOA for Scalability

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Grid-Enabled SOA for Scalability

10/26/2007

By Kurt Mackie

The use of data-grid technology in service-oriented architectures (SOAs) was the subject of a keynote address at the first annual IT Architect Regional Conference in San Diego, which took place last week. Dave Chappell, Oracle's VP and chief technologist for SOA, spoke on the topic of "Next Generation Grid Enabled SOA" at the IASA event.

Chappell described the sort of problems that happen when processing large amounts of XML data and trying to ensure reliability and scalability in an SOA.

Oracle's model for grid-enabled SOA stems from technology that the company acquired about seven or eight months ago when it acquired Tangosol. Oracle now offers this technology for mission-critical applications, typically involving extreme transaction processing, through its Coherence product line.

What Is a SOA Grid?
The SOA grid concept is based on the data grid concept, Chappell said. A data grid is a set of cooperating software nodes that know how to work together to manage the ownership of instance data for any given Java object or .NET object that you have in your application.

Applications use familiar data structures, such as a Java hash map or a .NET collection, and then put data into that collection, and that's basically handed off to the grid. Then, the grid automatically elects a primary owner and a backup owner for that piece of instance data for that given application. And it does all of that in memory, so there's no dispersed systems required. This is how the system achieves high availability, Chappell explained.

The nodes on the grid are aware of each other. They are constantly in communication with each other about what instances of data they are owning and the health status, so that if the primary owner of something goes down, the other grid knows automatically to detect that and reelect a new primary and backup owner for that piece of instance data. And that can happen in the middle of updating a transaction.

SOA Solutions, SOA Problems
Chappell explained that much of the technologies associated with SOA have been worked out, but a set of problems still exists. While people speak of SOA as a means for reducing cost and complexity, those aren't the biggest reasons to implement an SOA. Achieving business agility is far more important, and SOA enables it.

"By building flexible business processes, we're able to take advantage of these new services that we are building and recombine them in ways that are better suited to meet the needs of business--and allow IT to better react to the requests for changes that are coming from the business at ever-increasing rates," he said.

A few noteworthy technologies and concepts have helped enable SOAs, including:

The use of business process orchestration tools, such as Business Process Execution Language (BPEL) engines;
Basic SOA patterns for building composite apps that are constructed from service functionalities; and
Loose coupling and modularity.

However, in the process of using these technologies--and by choosing to use XML as the means for exchanging data between apps and services--the size of the data that is being shipped around has been inflated by a factor of five, Chappell said.