Archive for the ‘Technology’ Category


I decided today that I would take a look at a long-standing yet still active project, the bulk of which is in Java and running quite well under the latest v17 (LTS). In particular I wanted to know how much of the library of dependencies was compiled with earlier versions of Java. The result makes for some interesting reading.

My strategy was to extract the classes from every Jar and examine the version ID in the preamble bytes. I would then weight the discovered versions by the size of the class files (in uncompressed bytes), because counting files or lines of code is so unreliable.

From a total sample of about 5Gb of Java class bytes, only half of one [click title to read more…]

Sitting with elephants

It has been a long time since I dropped an article onto the public side of the fence. Assuming this will one will also be public, that makes a total of two for this year! It’s fair to say that I’ve not been active in public for a while.

In similar vein, I posted only 30 times on Twitter this year, but the chaos that started around April made me pause my account at the end of October, and then in November I deleted the app and have removed its embedding from my site. Mid-November I joined a local Mastodon instance, popped a few shillings in its pot for the upkeep, and am rather liking what I’ve seen so far. [click title to read more…]

A decade later

Every now and then I have to pull out all the stops and migrate legacy systems to the latest-and-greatest, leaping over several intervening versions of programming languages and platforms. Recently I have been migrating systems that have been stable for a decade or more but need to be upgraded in order to avoid their underlying systems going completely out of support. There are several technologies involved, but three of them are “old friends” and while I am looking at the migration process I am also astounded by the many positive changes that have occurred in the past decade. While most of the changes don’t have much effect on process, some of them are quite significant. Some changes are minor, but [click title to read more…]

Dragged by the roots

This one had me scratching my head for a while today. A client and an ex-client both contacted me with strange HTTP connectivity issues, which manifest as errors occurring on one server while the exact same code is working elsewhere. The logs revealed that a HTTPS connection was being rejected because the connection to the external site could not be validated. The problem was that the root certificates were out of date, and the external site was using Let’s Encrypt SSL certificates, which as of this month (October 2021) has a new compatibility restriction meaning their certs can only be validated by a client if the client trusts the ISRG Root X1 certificate. That restriction prevents functionality on iPhones running [click title to read more…]

Bare bones bleeding edge cluster


Audience: SysAdmin, DevOps, Un*x coders

Sometimes, just for exercise, I go nuts. This time I figured my exercise would be to create a Hello World micro-services demo by building a bare bones cluster on the bleeding edge Rocky 8.4 operating system. I say “bleeding edge” but in fact I would just be using recent stable versions of several technologies, rather than the actual bleeding edges.

You can read about my chosen technologies elsewhere, along with all manner of explanations, charts, diagrams and occasionally some sample configurations or lines of code. For this document I stick to command lines and raw configurations, with the aim of providing something that you can copy/paste verbatim and achieve the same result. If you [click title to read more…]