The following text is copyright 1997 by Network World, permission is hearby given for reproduction, as long as attribution is given and this notice is included.

Illusionary advantages

Imagine if you will, that you have two ways to implement your application. With one design your application appears to the user to be faster than if the second design is used. But the other design produces a reduced load on the infrastructure it runs over. Which would you choose?

One way is better for the community but at the cost of having a product that may not seem ''as good'' as the competition's product. The other way your immediate goal of making the product look better is satisfied but in the long run the system overloads may dampen the overall market.

This is the same type of conflict that Garrett Hardin explored in his 1968 Sciencearticle , The Tragedy of the Commons.,. ( - thanks AltaVista) In this article Hardin describes a type of problem that ''has no technical solution.''

These are problems in which there is a balance of costs and benefits in a course of action. The benefit of the action is wholly gained by the individual and the costs are shared by all. This produces an inbalance that makes it hard for the common good to be considered fairly.

This conflict was brought to mind by reports about the performance improvements in the new version of the HTTP (web) protocol. HTTP 1.1 defines a process in which a web client can establish single, long lived, communications session with a web server. This is known as a ''persistent session.'' The session lasts until all the individual files that make up a Web page have been transferred from the server to the client. In previous generations of HTTP separate short-lived sessions had to be created for each element. Using the single session it can take far less time to download the page and the load on the server and the network infrastructure are considerably less.

But using a single persistent session may not appear to be faster. Some current browsers open a number of sessions in parallel to retrieve the elements. This can look better because the whole page grows at the same time rather than from top to bottom. This produces an illusion of an advantage. The page takes longer to download but seems to be appearing quicker.

There are many other instances of this conflict in the networking world. For example, or a number of years there have been stories that one or another workstation vendor changed the Ethernet backoff algorithm to ensure that their device could access the Ethernet at a higher priority, at the expense of other devices on the same net.

This technology is designed with the overall user community in mind. The only solution is for customers to find out what path their vendors have chosen and for the customers to insist that any advantages are real for the whole user community not just an individual.

disclaimer: While no sheep graze on the Harvard common that is more for sanitary rather than resource exhaustion reasons and the above meanderings are my own.