Kev’s Blog – Page 83 – Kev's Development Toolbox

February 19, 2020February 19, 2020

Why does the C programming language (and other C-like languages) have pre and post operators?

This is an interesting question that has a common answer that turns out to be a myth/historically incorrect.

TLDR; the definitive answer to this question comes from Dennis Ritchie himself, developer of the C language in his article “The Development of the C Language” – http://www.bell-labs.com/usr/dmr/www/chist.html

“Thompson went a step further by inventing the ++ and — operators, which increment or decrement; their prefix or postfix position determines whether the alteration occurs before or after noting the value of the operand. They were not in the earliest versions of B, but appeared along the way. People often guess that they were created to use the auto-increment and auto-decrement address modes provided by the DEC PDP-11 on which C and Unix first became popular. This is historically impossible, since there was no PDP-11 when B was developed. The PDP-7, however, did have a few `auto-increment’ memory cells, with the property that an indirect memory reference through them incremented the cell. This feature probably suggested such operators to Thompson; the generalization to make them both prefix and postfix was his own. Indeed, the auto-increment cells were not used directly in implementation of the operators, and a stronger motivation for the innovation was probably his observation that the translation of ++x was smaller than that of x=x+1.
From http://www.bell-labs.com/usr/dmr/www/chist.html

The common answer which turns out to be incorrect is (paraphrasing) “C has pre and post operators because C was developed on the PDP-11 and this machine had pre and post CPU instructions, the implementation of ++ and — in C used these machine instructions”.

The explanation from Ritchie that corrects this misconception:

“People often guess that they were created to use the auto-increment and auto-decrement address modes provided by the DEC PDP-11 on which C and Unix first became popular. This is historically impossible, since there was no PDP-11 when B was developed”
From: http://www.bell-labs.com/usr/dmr/www/chist.html

An interesting piece of computing history.

February 11, 2020February 11, 2020

What happened to the proliferation of Java web frameworks from the early 2000s?

Back in the early 2000s if you were a Java developer working on building web apps, chances are you were using Apache Struts. It was the de facto, go-to web framework of it’s time, pretty much used everywhere by everyone (it was even noticeable online for it’s pattern of using ‘*.do’ URLs for its Actions). However, it wasn’t the only framework in town. Around early to mid 2000s there was an explosion of Java based web frameworks being developed, for a while it seems like it was the-thing-to-do to build your own web framework because after all, you know better than all the other guys right?

Joking aside, other major frameworks that appeared, some of the other big names were Wicket, Cocoon, Tapestry, Webwork (Webwork and Struts merged to form Struts 2), GWT and Vaadin. In the Java EE space the standard web framework became JSF but never really gained traction over any of the others. The one that stayed the course and probably the only one still in serious usage would be Spring Web MVC.

The funny thing about all this churn that occurred is that it feels like it’s all happening again, but now in the Javascript space. Sure, once we realized we could could offload some of this backend rendering of the UI to the frontend and after Google had shown the way with GMail showing us how the user experience of a single page app is far better than the traditional request/response of web apps we had become used to, it was inevitable that serverside based Java web frameworks would fall out of favor and get replaced by Javascript clientside frameworks. Was it inevitable that the industry would go through the same learning pains once again though? I’m not sure, but it happened.

At one point jQuery was the de facto JavaScript framework, much like Struts was in the Java space back in it’s time. Then came the flood: backbone, ember, Dojo, Knockout seemed to to be the main players, eventually settling down to ‘the big 3’ that we have today, Angular, React and Vue.

So what happened to all the Java web frameworks? Spring Web MVC is still around and still in use. With the change in technologies and a shift in focus from backend web frameworks to frontend, the backend web frameworks became less relevant. Could this shift happen again? Sure, when the next big things comes along.

Moral of the story: tech changes quick in software development. Keep an eye out for whats coming next, because what’s hot today can quickly become irrelevant tomorrow.

Additional reading: if you’re interested to read more about Java web frameworks, Zeroturnaround’s Rebel Labs used to do a survey on framework usage, and you can see their findings from their relatively recent reports, from 2014, 2015 and 2017:

https://www.jrebel.com/blog/java-tools-and-technologies-landscape-2014#Web%20Frameworks

https://www.jrebel.com/blog/java-web-framework-usage-stats

https://www.jrebel.com/blog/java-web-frameworks-index

January 25, 2020January 25, 2020

Replacing a failed CD-ROM in a Sun Ultra 60

The CD-ROM drive in the Sun Ultra 60 that I recently picked up from ebay lasted long enough to get an initial install of Solaris 10 installed, and then the tray refused to stay closed. I picked up a replacement used DVD drive from www.anysystem.com

It came with free plastic ducks. Yay!

One thing I’ve noticed is that used retro computer gear is often shipped with far more care and with better packing than new gear – good job on the packing anysystem.com:

Here’s a side view of what the Sun Service Manual for the Sun Ultra 60 calls the ‘Removable Media Assembly’, or RMA:

Here’s the front view before removing the face plate:

The front plate is removed by squeezing the left and right sides then it pops off. Remove the screws seen here on the front left and right:

… and then the whole RMA section slides out:

Undo the 2 screws on the left and right of the CD-ROM drive, remove the cables at the back and then slide it out of the assembly. Here’s the CD drive out, and the new DVD drive inserted:

RMA pushed back into place and front plate re-attached. Done!