Distributed Computing Fallacies Explained: "Transport Cost is Zero "

On to Distributed Computing Fallacy number 7--"Transport cost is zero". There are a couple of ways you can interpret this statement, both of which are false assumptions.

One way is that going from the application level to the transport level is free. This is a fallacy since we have to do marshaling (serialize information into bits) to get data unto the wire, which takes both computer resources and adds to the latency. Interpreting the statement this way emphasizes the "Latency is Zero" fallacy by reminding us that there are additional costs (both in time and resources).

The second way to interpret the statement is that the costs (as in cash money) for setting and running the network are free. This is also far from being true. There are costs--costs for buying the routers, costs for securing the network, costs for leasing the bandwidth for internet connections, and costs for operating and maintaining the network running. Someone, somewhere will have to pick the tab and pay these costs.

Imagine you have successfully built Dilbert's Google-killer search engine (maybe using latest Web 2.0 bells-and-whistles on the UI) but you will fail if you neglect to take into account the costs that are needed to keep your service up, running, and responsive (E3 Lines, datacenters with switches, SANs etc.). The takeaway is that even in situations you think the other fallacies are not relevant to your situation because you rely on existing solutions ("yeah, we'll just deploy Cisco's HSRP protocol and get rid of the network reliability problem") you may still be bounded by the costs of the solution and you'd need to solve your problems using more cost-effective solutions.

Posted by Arnon Rotem-Gal-Oz at 07:47 AM  Permalink