SEDA is an acronym for staged event-driven architecture, and decomposes a complex, event-driven application into a set of stages connected by queues. This design avoids the high overhead associated with thread-based concurrency models, and decouples event and thread scheduling from application logic. By performing admission control on each event queue, the service can be well-conditioned to load, preventing resources from being overcommitted when demand exceeds service capacity. SEDA employs dynamic control to automatically tune runtime parameters (such as the scheduling parameters of each stage), as well as to manage load, for example, by performing adaptive load shedding. Decomposing services into a set of stages also enables modularity and code reuse, as well as the development of debugging tools for complex event-driven applications. Their current prototype of a SEDA-based services platform is called Sandstorm. Sandstorm is implemented entirely in Java and uses the NBIO package to provide nonblocking I/O support. Support for the JDK 1.4 java.nio package is included as well. This has been added to World Wide Web Reference Subject Tracer™ Information Blog.
posted by Marcus Zillman |
4:43 AM
