we study a profit-maximizing firm selling two substitutable products in a price and time sensitive market. The products differ only in their prices and delivery times. We assume that there are dedicated capacities for each product and that there is a standard industry delivery time for the regular (slower) product. The objective of the firm is to determine the delivery time of the express (faster) product and appropriately price the two products, taking into consideration the impact of delivery time reduction on capacity requirements and costs. We develop a model that integrates pricing and delivery time decisions with capacity requirements and costs, and study scenarios where the firm is constrained in capacity for none, one, or both product(s). We showhowpr oduct differentiation decisions are influenced by capacity costs, and howthe firm should adapt its differentiation strategy in response to a change in its operating dynamics. We first identify a market characteristic that governs the optimal pricing structure. We then showthat the degree of product differentiation depends on both the absolute, as well as the relative values of the capacity costs. Provided that the capacity cost differential remains the same, higher capacity costs induce less time differentiation and less price differentiation. An increase in capacity cost differential increases price differentiation, but decreases time differentiation. The optimal prices depend, in addition to the above, on the market characteristic. We find that prices can actually decrease when the firm incurs capacity-related costs. We also explore the impact of substitutability on product differentiation, and illustrate our results in a numerical study.

By sharing and hosting personal Web content in a peer-to-peer (P2P) fashion, we may increase the bandwidth of retrieval and improve the reliability of retrieval. The cost is that the Web content has to be replicated to and stored in the peers, consuming valuable network bandwidth and peer storage space. In this work, we develop two technologies, namely hierarchical content organization with unequal weight assignment and erasure coding, to reduce the amount of content to be distributed, yet still maintain the retrieval speed up and reliability. Significant improvement over the ordinary Web server is demonstrated.

Today, more and more people rely on the wealth of information available on the World WideWeb, and thus, increased exposure on the web may yield significant financial gains for organizations.Often, search engines are the entryways to the web. That is why some people try tomislead search engines, so that their pages rank high in search results, and thus, capture userattention.Hence, just as with emails, we can talk about attempts of spamming the content of theweb. The outcome is that the quality of search results decreases. For instance, for the query“kaiser pharmacy,” the top 10 results returned by a major search engine (on March 12, 2004)contained 7 pages that had nothing to do with pharmacies related to the Kaiser Permanentehealth delivery system. The top result page actually directed the user to sites of questionablevalue, selling “cheap” diet drugs and “discount” male potency products. Some other resultstried to lure users with pharmacy job offers, or take them to senior citizen humor pages.To provide quality services, it is critical for search engines to address web spam. Searchengines currently fight spam with a variety of often manual techniques, but as far as we know,they still lack a fully effective set of tools for combating it. We believe that the first step incombating spam is understanding it, that is, analyzing the techniques the spammers use tomislead search engines. A proper understanding of spamming can then guide the developmentof appropriate countermeasures.1To that end, in this paper we organize web spamming techniques into a taxonomy that canprovide a framework for combating spam. There have been brief discussions of spam in thescientific literature [4]. One can also find details for several specific techniques on the web itself(e.g., [9]). Nevertheless, we believe that this paper offers the first comprehensive taxonomy ofall important spamming techniques known to date. To build our taxonomy, we worked closelywith experts at one of the major search engine companies, relying on their experience, whileat the same time investigating numerous spam instances on our own.Some readers might question the wisdom of revealing spamming secrets, concerned thatthis might encourage additional spamming. We assure readers that nothing in this paper issecret to the spammers; it is only most of the web users who are unfamiliar with the techniquespresented here. We believe that by publicizing these spamming techniques we will encourageresearchers to develop appropriate countermeasures.

It is imperative for a competitive e-business outsourcing service provider to manage the execution of itsservice level agreement (SLA) contracts in business terms (e.g., minimizing financial penalties for service-level violations, maximizing service-level measurement based customer satisfaction metrics, etc.). In order to do that, the provider must possess a generic means of capturing and managing the SLA contract data (e.g., quality measurement data sources, service-level evaluation rules, etc.) as well as the relationships between them and internal service-level management (SLM) data (e.g., resource management data, system configuration data, etc.). This paper presents the design rationale of a generic SLA semantic model (including a set of semantic elements and relationships) based on an in-depth analysis of nine real ebusiness outsourcing SLA contracts/templates comprising over 100 servicelevel guarantees and intents. Our development experience with a state-of-the-art SLA contract execution manager (named SAM) suggests the semantic model is practical and useful.

As Web-based transactions become an essential element of everyday corporate and commerce activity, it becomes increasingly important for the performance of Web application services to be predictable and adequate even in the presence of wildly fluctuation input loads. In this work we propose a general implementation framework to provide quality of service (QoS) guarantee for cluster-based Web application services, such as E-commerce or directory service, that is largely independent of the Web application and the hardware/software platform used in the cluster. This paper describes the design, implementation, and evaluation of a Web request distribution system called Gage, which is able to guarantee a service subscriber a predefined number of generic Web requests serviced per second regardless of the total input loads at run time. Gage is one of the first, if not the first systems that can support QoS guarantee which involves multiple system resources, i.e., CPU, disk, and network. The fully operational Gage prototype shows that the proposed architecture can indeed provide a guaranteed level of service for specific classes of Web accesses according to their QoS requirements in the presence of excessive input loads. In addition, empirical measure-ment on the Gage prototype demonstrates that the additional performance overhead associated with Gage?s QoS guarantee support for Web service is merely 3.06%.

ReplicatingWeb documents at a worldwide scale can help reduce user-perceived latency and wide-area network traffic. This paper presents the design of Globule, a platform that automates all aspects of such replication: server-to-server peering negotiation, creation and destruction of replicas, selection of the most appropriate replication strategies on a per-document basis, consistency management and transparent redirection of clients to replicas. Globule is initially directed to support standard Web documents. However, it can also be applied to stream-oriented documents. To facilitate the transition from a non-replicated server to a replicated one, we designed Globule as a module for the Apache Web server. Therefore, converting Web documents should require no more than compiling a new module into Apache and editing a configuration file.