In our last newsletter we suggested that the industry is entering a new era of mainframe computing. In that newsletter we began the process of looking at the end user devices of the original mainframe era and compared and contrasted them to the end user devices of the emerging era of mainframe computing. We will continue that process in this newsletter.
As discussed in the last newsletter, in the original era of mainframe computing that was based in part on the IBM 3270 terminal, users were generally presented with forms to fill out. The user moved about the form with arrow, tab, and backtab keys, filling in and correcting the various fields. When finished, the user pressed the Enter key.
Led in part by the deployment of what was originally called the Citrix Presentation Server and is now called XenApp, most IT organizations have at least partially adopted a thin client approach to computing. In this context, a thin client, like the old 3270 terminal, is a program that relies on another computer, typically a server, in order to function. The thin client could reside on a low-end computer terminal, which concentrates solely on providing a graphical user interface to the end-user, or it could reside on a fully functional PC. In either case, today’s thin client functions a lot like the old IBM 3270.
The use of thin client computing is about to get a major boost due to the adoption of virtual desktop solutions. To date, desktop virtualization has not been as popular as server virtualization. However, our research indicates that within the next year, that the number of IT organizations that have not implemented desktop virtualization will be cut in half.
There are two fundamental forms of desktop virtualization. They are client-side virtualization and server-side virtualization. Client-side virtualization is based on a model in which applications are streamed on-demand from central servers to client devices over a LAN or a WAN. On the client-side, streamed applications are isolated from the rest of the client system by an abstraction layer inserted between the application and the local operating system. In some cases, this abstraction layer could function as a client hypervisor isolating streamed applications from local applications on the same platform.
Client side application streaming creates some significant WAN performance problems. For example, the code for streamed applications is typically transferred via a distributed file system protocol, such as CIFS, which is well known to be a chatty protocol. Hence, in order effectively support application streaming, IT organizations need to be able to optimize the performance of protocols such as CIFS, MAPI, HTTP, and TCP. In addition, IT organizations need to implement other techniques that reduce the bandwidth requirements of application streaming.
Because applications are streamed to a user’s device and then function there, the user’s device cannot be as thin as it can be in the case of server side virtualization. In our next newsletter we will discuss server side virtualization. That newsletter will examine the impact that server side virtualization has on the WAN and it will answer the question: how thin can you get?