The idea of ‘eventual consistency’ was an Ah-Ha! moment in the history of e-commerce. With it, Amazon.com was able to throw away the traditional play book of transaction processing. But ‘eventual consistency’ is not a blank check. It requires developers – some of them, anyway – to make a large new conceptual leap.
The notion arose from our recent SearchSOA.com conversation on SimpleDB with Christopher M. Moyer, vice president of technology at Newstex LLC, who spoke with us on the topic of the Amazon cloud. The topic was no coincidence – Moyer is the author of Building Applications on the Cloud (Addison-Wesley, 2012), a book that neatly describes many basic patterns of cloud computing based on concrete examples.
”SimpleDB is one of the hardest databases to comprehend,” Moyer said. ”Everyone is used to the idea that, if they write a record to the DB, it will be there. ‘’
But the standard approach of SimpleDB is that marvel: eventual consistency, which is great but unfamiliar to a large legion of developers.
It is a difficult topic for developers to understand and work with in their systems, he told us.
Amazon, like other cloud pioneers, has seen a way toward supporting the familiar, but this too needs special attention.
”They have worked to address [the gap] with a ‘consistent mode,’ but you should be aware that it can affect your performance and stability,” Moyer said.
”Simple is not always simple,” the SearchSOA.com editor said.