document: Lock-free consistency control for web 2.0 applications Online collaboration and sharing is the central theme of many web-based services that create the so-called Web 2.0 phenomena . Using the Internet as a computing platform , many Web 2.0 applications set up mirror sites to provide large-scale availability and to achieve load balance . However , in the age of Web 2.0 , where every user is also a writer and publisher , the deployment of mirror sites makes consistency maintenance a Web scale problem . Traditional concurrency control methods ( e.g. two phase lock , serialization , etc. ) are not up to the task for several reasons . First , large network latency between mirror sites will make two phase locking a throughput bottleneck . Second , locking will block a large portion of concurrent operations , which makes it impossible to provide large-scale availability . On the other hand , most Web 2.0 operations do not need strict serializability - it is not the intention of a user who is correcting a typo in a shared document to block another who is adding a comment , as long as consistency can still be achieved . Thus , in order to enable maximal online collaboration and sharing , we need a lock-free mechanism that can maintain consistency among mirror sites on the Web . In this paper , we propose a flexible and efficient method to achieve consistency maintenance in the Web 2.0 world . Our experiments show its good performance improvement compared with existing methods based on distributed lock .
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