DIMACS TR: 2003-15

Towards an Efficient Cluster-based E-Commerce Server

Authors: Victoria Ungureanu, Michael Katehakis, Benjamin Melamed


Cluster-based server architecture combines combines good performance and low cost, and is commonly used for applications involving high volume traffic of requests. Essentially, a cluster-based server consists of a front-end dispatcher and several back-end servers. The dispatcher receives incoming requests, and then assigns them to back-end servers, which are responsible with request processing. The many benefits of cluster-based servers make them a good choice for e-commerce applications as well. However, applying this type of architecture to e-commerce applications is hindered by the fact that an e-commerce cluster has the additional task of validating requests, i.e. it has to verify that requests comply with contract terms. The problem is further complicated by the fact that contract terms may be expressed in terms of dynamic, mutable state. The problem we are addressing in this paper is how can e-commerce requests be assigned for processing so that load can be balanced among back-end servers and validation of requests can be done in a efficient manner.

To deal with this problem we propose that each stateful contracts is a-priori assigned to a back-end server, called the base of this contract, which is responsible for maintaining its state. The dispatcher assigns requests in the following manner. A request governed by a stateless contracts is assigned to the least loaded server. A requests governed by a stateful contract is assigned to its base whenever the base is not overloaded. If the base is heavily loaded, the dispatcher assigns the request to the least loaded server. Only, in the last case the back-end server needs to contact the base to retrieve the state. To enable a back-end server to detect when the state is needed, we propose a contract formulation that explicitly states the contract type.

Paper Available at: ftp://dimacs.rutgers.edu/pub/dimacs/TechnicalReports/TechReports/2003/2003-15.ps.gz

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