Services on Demand Architecture

Enterprise architects are faced with a wide and often confusing variety of deployment options for configuring corporate applications that are accessed not only by employees but also by customers and business partners. These applications can include legacy mainframe, traditional client-server, Web-based, and other applications. The challenge is to create a unified framework where all these different software technologies can be easily managed, deployed, and universally accessible. Conceptually, all these applications can be considered as services. When a user needs a service, it should be immediately available on demand. A Services on Demand architecture consists of a framework of completely integrated technologies that empowers enterprise architects to develop, manage, integrate, and deploy any application within an open standards-based set of protocols that can be accessed by any Web client running on any device such as PC desktops, laptops, PDAs, or cell phones.

Sun ONE is a set of products that uses an open standards-based software architecture. Sun ONE is designed for implementing and deploying Web-based applications, also known as Services on Demand.

The tiers are usually segregated based on functionality and security. The front tier usually performs some form or presentation functionality. The Application tier usually performs the business logic, and the Data tier maintains persistent storage of data. In actual practice, the tiers are usually less distinct because of optimizations for security or performance. In addition, designs will vary due to optimizations for performance, availability, and security. These directly impact the network architecture.

The Sun ONE architecture spans the Web, Application, and Data tiers. However, the focus is on the Application tier. Sun ONE provides a common framework where all these components can be developed, implemented, and deployed, being assured of tested and proven integration capabilities.

FIGURE 2-1 illustrates the main components of a typical multi-tier architecture for deploying Web-based applications. Note the firewall component is not included in this illustration to simplify the focus of this discussion.

Figure 2-1. Main Components of Multi-Tier Architecture