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Application DistributionIn order to avoid congested portions of the Internet, many companies are deploying content distribution networks. These networks consist of edge servers deployed at several ISP (Internet Service Provider) access locations and network exchange points to improve the response time of an Internet site by offloading the delivery of bandwidth-intensive objects, such as images and video clips. We are working on an intelligent Internet infrastructure that improves the performance and scalability of distributed applications by moving the bulk of their computation to servers located at the edge of the network. Within this framework, applications are logically split into two components, one that can be executed at an edge server close to the user, while the other executes on a traditional application server (see figure). Figure 1. Application offload environment The expected benefits of application offload include better scalability, higher availability, and improved response time from a centrally managed solution. The nodes constituting the distribution network are designed to be as self-configuring, self-managing, self-diagnosing, and self-healing as possible so as to ensure easy management and operational convenience. Some of the challenges in application offload include keeping consistency among the enterprise data hosted by the offloaded applications; sharing session state among edge and origin application servers; distribution, configuration, and management; developing programming models consistent with current industry standards such as J2EE; and application security. Our work in this area involves research into general frameworks that
can be used to support distributed applications, as well as prototyping
the ideas for specific application instances. Offloading a PortalPortal servers, such as IBM WebSphere Portal Server, allow users to access content and applications from a single access point. With their personalized portal, users can create persistent, customized views of applications and content chosen from the set of applications and content by the portal administrators. Since the portal server pages are personalized and often include dynamic content, there is a significant amount of computation required for page assembly making it an excellent candidate for application offload. We are currently developing a prototype of a distributed version of
the IBM WebSphere Portal Server to take advantage of the performance and
scalability benefits. This work will provide lessons for designing a general
framework. Offloading an Enterprise DirectoryA common e-Workplace tool is the electronic employee directory. For such an application, the employee data is often stored in a central LDAP directory, and there is a separate web-based application providing the interface to the directory (see Figure 2). Figure 2. Directory application environment While the centralized directory is convenient to manage, the performance for clients accessing the directory from remote sites can be poor due to the characteristics of the network connecting the remote sites. For example, transcontinental network connections suffer from a long delay. IBM's internal employee directory application, called BluePages, serves over 300,000 employees in six continents. We are currently developing an offloaded version of the BluePages application with an architecture as shown in Figure 3. Figure 3. Directory offload architecture We intend to analyze the performance of this offloaded version of BluePages
in the laboratory, and later deploy it as a production system for further
performance studies. Resources
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