HTTP response codes

I found this activity diagram, in this page, strolling around the internet and i found it very interesting. It shows what happens from the momment the server gets the request from the client and how he decides what response code to send to the client. You must have...

Nested Sets vs Adjucency Matrix

I have been using trees as structures to store data, such as categories in a forum. In most cases what happens is that you create a node, for instance a category, that may or may not have a parent. This is called an adjucency matrix, because what you do is, in each...