What is wrong with UUIDs and GUIDs

Introduction

Universally Unique Identifiers (UUIDs) otherwise known as Globally Unique Identifiers (GUIDs) are 128-bit numbers that are often used to identify information. In its canonical representation, a UUID looks like this: 2205cf3e-139c-4abc-be2d-e29b692934b0.

The Wikipedia entry for Universally Unique Identifier (⬀) says that they are for practical purposes unique and that while the probability that a UUID will be duplicated is not zero, it is so close to zero as to be negligible. Wikipedia then does the math and shows that if 103 trillion UUIDs are generated, the chance of duplication among them is one in a billion.

Despite the infinitesimally small chances of receiving a duplicate UUID, there exist programmers out there who are afraid of this actually happening, and who will not hesitate to suspect duplicate UUIDs as being responsible for an observed malfunction rather than first look for a bug in their code. Clearly, these folks do not understand the meaning of infinitesimally small chance, so let me try to explain it:

Infinitessimally small chance means practically impossible to happen, and the practically part is only mentioned for scientific correctness: practically, you can disregard the word practically and consider it as simply impossible to happen.

Great. Now, let me tell you why I hate UUIDs.

6 videos from TechSummit Amsterdam 2017 (Jun 1st)

A couple of weeks ago some of us went to the TechSummit conference organized by LeaseWeb.  Here is a list of the talks that I attended, along with a short description for each.

The first presentation was “Shaving my head made me a better programmer” by Alex Qin, which was about what it is like to be a woman, and specifically a programmer, in the U.S. tech industry.  (And in the University before that.)  She talked about the inequality, the sexism, and the harassment.   She mentioned that she once gave a talk in a really big conference about accessibility in the U.S., and afterwards she was asked “How do I talk to women at bars?”  The head-shaving part refers to how changing her appearance resulted in being taken more seriously.  It was quite an interesting talk, though I suspect that in Amsterdam, she was to a large extent preaching to the choir.

 

My notes on the Fielding Dissertation (REST)

These are my notes on Roy T. Fielding's famous Ph.D. dissertation "Architectural Styles and the Design of Network-based Software Architecture"

What follows are excerpts from the dissertation, with my notes usually in parentheses.

Roy Thomas Fielding is: chief Scientist in some tech company; Chairman, Apache Software Foundation; Visiting Scholar, W3C @ MIT CS Lab; etc; Publications, Honors, Awards, Fellowships etc. Involved in the authoring of the Internet standards for the Hypertext Transfer Protocol (HTTP) and Uniform Resource Identifiers (URI).

Abstract:

"The World Wide Web has succeeded in large part because its software architecture has been designed to meet the needs of an Internet-scale distributed hypermedia system."

(He makes it sound as if it was designed this way on purpose.)

"In order to identify [...] aspects of the Web that needed improvement and avoid undesirable modifications, a model for the modern Web architecture was needed to guide its design, definition, and deployment."

(So, he admits the need to build a model after the fact.)

"An architectural style is a named, coordinated set of architectural constraints."