Fighting with computers

Computers are not always friendly.

Wednesday, December 24, 2008


For a new assignment for my students I decided to show them they could build a simple P2P software. So I prepared a simple P2P protocol specification and a sample implementation. The whole system was design with the idea that students might run several peers on a single computer (for testing purposes). Effort was put on making it simple to understand and to implement (and to test), there are many improvements possible that will boost performance but those were rejected in favor a simple system.

I did search on the net for a simplistic P2P but I did not find that so I wrote this. I like to hear from other simple P2P protocols you may know.

Sunday, December 14, 2008

Three cool tools from Google

Like many of you I do have a hard time trying to keep up with all the new services offered by Google. I've been testing a few of them recently and I've found them quite useful:
  • Google Analytics is yet another service that will inform you about who, when and where you're site is getting visits from.
  • Google Sites enables you to create a website just yourself of with a few collaborators of your choice. No HTML knowledge seems needed. Up to 100MB of free storage is provided too.
  • Google Trends allows you to know whether a certain search term is becoming more or less popular lately by know how many searches are using it over time.
None of these services is really new but now that I've come to use them I can recommend them. Given they are all free services I cannot complain about the price.

Tuesday, December 09, 2008

Better batteries for arduino wireless sensors

It was pointed out in a previous post that CR2032 batteries won't be happy with 60mA peak consumptions (ie: battery voltage will drop causing the sensor to stop working very soon). I've been looking for a better choice while still small and light. A tip from a colleague seems to be a very good choice: ER1450 from this catalog.

Wednesday, December 03, 2008

Pay-per-bid auctions

Like many of you, I'm familiar with auction sites like eBay that allow you to bid on a certain item following the model of an auction: Winner is the user that makes the highest bid. Item price is just that winning bid.

eBay makes money charging a fee for each transaction. (I know there are many details, happy and unhappy sellers and bidders but that is another story).

What surprises me is that several companies are advertising their sites as auctions with a certain twist. Apparently they offer a real bargain, where "winning bidders" may save more than 90% of the retail price of a brand-new item.

I prefer not to include any link to these companies, but they all share a common feature: While they use the word auction they are not really meaning that. The fine print details explains (to the attentive reader only) that you have to pay to make a bid and that only your bid can become a winning bid by chance (without you having all the information at all times). Instead of the item price to go up because of your bid, it may even go down. These companies make money not on the final sale price of an item but on the many bidders that won't make it (in fact, all but one lucky bidder will get the product). It's actually a lottery in disguise: The more tickets you buy, the higher the chances of winning the bid. The problem is that, like lottery, buying many tickets may become expensive, even much more than the real cost of the item. After all, how do you think they can give away a very expensive car for just one dollar?

I've come to the term of pay-per-bid as what I thought it was a thoughtful term, Google shown it is not a new term at all. Of course these auction sites will avoid that term at all times because it explains it all. They want customers to be fooled by the amazingly low prices winning bidders are getting. Given the way they work, these companies may give away products and still make a profit.

Greedy bidders don't realize they've been outsmarted by a dubious business model. Apparently it is a legal business in my country and, for the happy winning bidders, it is a great way of buying things cheaply.