Internet Application Serving: Just ask "Why?"

by William Henning
Editor, CPUReview
Copyright November 14, 1999
ALL RIGHTS RESERVED

Introduction

Last week I wrote an article for AboutLinux.com on "$oftware Rental"; it generated a surprising amount of feedback.

Most of the feedback agreed with my position (that such software rental is neither desirable nor long term tenable) however several individuals felt that I misunderstood thin client computing; and was unjustly ignoring WinTerminals, JavaStations and other means of server-centric application deployment.

The fact of the matter is that I am not ignorant of thin clients; I have used Citrix clients, X terminals, VNC, PC Anywhere, OS2You, telnet and ssh sessions.

I did not cover such solutions as I do not believe that they are a viable solution over wide area networks for the number of users a large ISP (hereafter referred to as Acme ISP) would have, although they may be quite suitable for some intranet based applications or for a limited number of remote users.

I am quite willing to listen to credible accounts of such large internet deployments; I like to think that I admit it when I am wrong - but everything I've seen to date suggests that I am not wrong .

Why do I not believe that they are suitable for mass deployment for general use over the Internet?

1. Latency
2. Bandwidth
3. Reliability
4. Security
5. Server Resource Requirements
6. Does not satisfy a need
7. Not good for 3D games
8. Poor performance

I will address each of the points above separately; then I'll wrap up this article with a conclusion.

1. Latency

All thin clients require relatively fast, low-latency connections between the client and the server; unfortunately the current Internet network infrastructure is often not up to the task.

One of the simplest forms of remote application execution is a remote text mode terminal session (3270, telnet, ssh etc.).

A simple terminal session sends only ASCII characters and cursor control codes. This should be simple should it not? After all, when you are typing you are not likely to be sending more than two or three characters per second!

Unfortunately the echo back from the remote servers often lags several characters behind; not because the connections are not fast enough, but because sometimes the packets cannot be routed for a short time.

An X windows or Citrix connection would also experience the same occasional lags; it can be quite frustrating to be typing ahead...

Now imagine a large Acme ISP with a few thousand simultaneous users... you can bet users will encounter latency issues.

NEXT: Bandwidth

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