Here is how Server-based Computing works (“Understanding Thin Client-Server Computing” by Joel Kanter):
All applications and data are deployed, managed and supported on the server. In addition, 100% of the application executes at the server. The application logic is separated from the user interface at the server and transported to the client. This separation means that only screen updates, mouse clicks and keystrokes travel the network.Thus, applications consume just a fraction of the normal network bandwidth usually required. Because applications require fewer resources, they can be extended from one location across any type of connection to any time of client with exceptional performance.
An article in Information Week (June 12, 2000) elaborates on the benefits of Server-based computing:
Maybe the mainframe guys got it right after all. Sure, they didn’t have a cool and intuitive graphical desktop like the PCs that are sprinkled throughout the enterprise, but they did come up with an architecture that provided the benefits of centralized management, a relatively low cost of ownership, and a resource that was clearly made for conducting business.
Visualize a centralized architecture combined with the power of the graphical interface and a simple desktop or even handheld user device. Think about simplifying the desktop, migrating complexity into a centralized controlled environment and minimizing weak links in the enterprise. Here’s what Gartner Group, Tolly Group, and Zona Research tell us server-based computing:
Empowers companies to reclaim 57% to 80% of costs associated with enterprise desktop computing.
Decreases staffing requirements by enabling administrators to manage 500-plus users, primarily through the concentration of up to 200 users per application server.
Reduces liability at the desktop and creates a zero-desktop-administration situation.
Introduces time-to-value benefits for deployments and software version control.
Improves performance of centralized enterprise apps, particularly those delivered over WAN and low-bandwidth connections.
Provides gateway connectivity for supporting heterogeneous systems on the back end while fostering a thin-client device on the desktop.
Provides the company with an architecture well-suited for long-term expansion, and flexibility without extensive system changes.
A more recent article by Andrej Volchkov in IT Pro (March-April 2002) weighs the pros and cons of server-based computing:
The principle advantages [of server-based computing] are reduced maintenance and support for client terminals, a standardized corporate client terminal and centralized resources management. All of these in turn make it easier to support increased employee mobility and the deployment of heavy client-server applications at remote locations or subsidiaries because of less bandwidth usage.
Server-based computing has disadvantages also; among the most important are that the terminal server represents a single point of failure. It is also not very suitable for deploying small business applications requiring local country or language support. Applications (particularly graphic-intensive ones) can also experience performance problems or become unavailable because of network problems, heavy printing demands, and large file transfers over low-bandwidth connections.
Even as we consider the benefits of server-based computing, we cannot overlook the downside the central server can be a single point of failure. Though technology has become increasingly reliable, it may become necessary to deploy a bank of servers which are load-balanced, rather than a single server. In addition, storage can be separated from the server through the use of a NAS (network-attached storage) or SAN (storage area network). It depends on the end user segment one is addressing and how much the customer is willing to spend. In fact, the most inexpensive solution could consist of using software-RAID on a single desktop computer which is used as a server, and using diskless desktops with limited processing power.
Tomorrow: Citrixs Solutions