The New York Times ran an article last Friday about the struggles people have had using all those vaccination-appointment web sites. The biggest complaint? The sites “crash” because they have too much traffic. I’ve worked at a company that runs scaled-up web technology. We have a customer with a vast seasonal rush, with millions of users active at any time… Read more →
Category: Programming
Testing web apps that require https, like WebRTC and getUserMedia
You’re developing a web app on localhost. It uses one of the many Web APIs that require your page to come from an https origin (or from localhost). getUserMedia(), WebRTC, and the Web Authentication API are examples. The hard way Now you want to show it to a friend. Now what? Do you have to do all this? Register a… Read more →
Firefox has limited ability to handle H.264
The Firefox browser’s WebRTC and MediaRecorder functionality can handle H.264 (Advanced Video Codec) coding and decoding, but only with H.264’s constrained baseline profile. Other, higher, profiles just don’t work. And in Firefox’s WebRTC implementation (v87) attempts to use higher profiles fail more-or-less silently. Firefox works around all the patent issues with H.264 by using an automatically downloaded plugin called “OpenH264… Read more →
The WebRTC standard has landed. At last!
The WebRTC (browser-to-browser realtime conferencing) standard landed as a W3C recommendation version 1.0 on 26-January-2021. Thanks everybody who worked on it! Maybe there’s a future without adapter.js ! Read more →
Web Beacon API
There’s a sweet little function in web browsers called the Web Beacon API. It’s a simplified version of the XHR or Fetch API that does a fire-and-forget POST operation to a server. It’s nice for a few reasons. First, browser Javascript (front-end Javascript) can use it without any need to process results coming back. Just call navigator.sendBeacon(). If your page… Read more →
Javascript exception tracebacks
Working with browser Javascript on mobile devices, I found myself needing to report exceptions back to a server. (It’s hard to see the browser console log on a mobile device without connecting it to a desktop machine). Here’s what I did to make a suitable object that can be serialized. To use this you’ll need stacktrace.js loaded in your web… Read more →
Find peak cases
Back in the Database Programming section of this series, we created the view named us_counties_new, showing the daily new case load. Recall that we first computed the seven-day running average of the total case loads in the us_counties_avg7 view, then used those numbers for the daily case loads. Having the daily case loads available lets us do some interesting analysis.… Read more →
Database programming
In the last section, we populated our us_counties table and used it for some queries. Now it’s time to create some views of the data. With views we’ll be able to do more interesting things without retyping huge queries. We can use views as a foundation for more analysis. The first view we need is the one to give us… Read more →
Getting started with the data
The Times’s data is here. https://raw.githubusercontent.com/nytimes/covid-19-data/master/us-counties.csv If you’re using a browser, open the context menu (right-click) on that link and use the Save Link As … operation to put it into a file on your system. We’ll use it later to load the database. Use your database interface program to log in to your database server, and figure out which… Read more →
Explore pandemic data with SQL
The New York Times newspaper publishes, every day, a file showing COVID-19 cases and fatalities for each county in the USA. They put their file on github here for anyone to use. So, let’s use it. Let’s download it and learn a few things about using SQL to explore data as we dig into it. Their file is called us-counties.csv.… Read more →
