WebSphere Application Server: a foundation for on demand computing

IBM Systems Journal,  July, 2004  by E.N. Herness,  R.H. High, Jr.,  J.R. McGee

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There is little doubt about the importance of e-business on demand *. (1) The information technology industry has come to a juncture with the next major step being one toward greater productivity--in terms of improving both the productivity of information systems specialists and, more importantly, the productivity of businesses that depend on information technology for conducting their business. This next step forward will be enabled by e-business on demand * through more efficient utilization of computing facilities by sharing resources among many lines of business, and by interconnecting those facilities into a computing grid that will enable access to more computing capacity on demand. This potential is then extended through e-business on demand by allowing lines of business to be interconnected as a seamless flow of information and business processing and by providing concrete definitions of customer business processes so that customers can adjust those processes rapidly as business conditions change.

The role of WebSphere * Application Server (2-6) in enabling on demand computing is significant in two ways. First, it is a container for application components whose very programming model design enables a high degree of virtualization. This is achieved in the underlying information system by separating the presentation and business logic of the application from the infrastructure hosting that logic. (7) Second, the application server is a resource manager--it manages application components as resources, and manages them in the context of the computing and information resources they depend on, including the execution environment, data systems, connections, transactions, security contexts, RAS (reliability, availability, and serviceability), messaging systems, and other application components. Both of these properties form a critical backdrop to enabling on demand computing.

WebSphere Application Server supports four major models of application design: multitiered distributed business computing, Web-based computing, integrated enterprise computing, and service-oriented computing. All of these design models focus on separating the application logic from the underlying infrastructure; that is, the physical topology and explicit access to the information system is distinct from the programming model for the application. Use of underlying resources within the information system is abstracted in the programming model by high-level interfaces and logical resource references and by encouraging service processing through declarative policies in the components. The appearance of control is given but in a way that can be mapped to physical resources by the application containers in WebSphere Application Server based on its management algorithms. Exploiting the component models defined in the WebSphere Application Server programming model makes programmers more productive, but it also enables the application to be managed by WebSphere Application Server. The application components can be located within the topology as needed on the basis of the resources required by the application, as measured by the availability and capacity of the underlying computing facilities, and on the basis of the relative requirements of the application as compared to other applications in use by the enterprise.

WebSphere Application Server provides support for deploying the application, managing the resource requirements for the application, ensuring the availability, isolation, and protection of the application from other applications and their resource requirements, and monitoring and securing the application. In the following sections we will survey various aspects of WebSphere Application Server and how it enables computing for e-business on demand. Included is a discussion of how applications are managed and deployed, how the application server is monitored to determine how efficiently it is using resources and how this affects workload management, bow applications can be profiled to enable the application server to serve its resource dependencies more efficiently, the infrastructure technology the application server uses to ensure high availability and failover, how this capability extends out to the edge of the network, and finally the role the application server plays in the area of grid computing.

Other aspects of WebSphere Application Server and much of the WebSphere platform, including approaches to obtaining maximum scalability from WebSphere Application Server, (8) how to improve performance by caching, (9) information integration, (10) portals, (11) business process choreography, (12) disconnected and rich clients, (13) and connectors and adapters (14) are discussed at length throughout this issue of the IBM Systems Journal.

Application models for e-business

One major characteristic of an on demand e-business is that it is dynamic. It changes at the rate and pace of demand--demand for business services, demand for information, and demand for computing capacity. An application will survive in this sort of environment only if it is designed for change. There are many application design patterns, (15) including the principles of structured and object-oriented programming, that describe techniques for achieving high degrees of reuse and component sharing.