Change Of IP Address last night, Downtime

I take the unusual approach of hosting my site and Blog, on my private PC at home, acting as a Web-server. It’s the computer I name ‘Phoenix’. Because of that, the visibility of my site is only as good, as the presence of my LAN on the Internet.

At the same time, my connection to the Internet is ‘only’ a domestic DSL, which achieves speeds of up to 50Gbps. This means that my ISP, is capable of changing the IP address at any time, with which my LAN is connected to the WAN. This is a right which they have, and is referred to as conventional ‘DHCP’.

Last night, my ISP did change the IP address, with which my LAN connects to the Internet. And what this means to my readers is, that from about 2h47 until about 3h17 this morning, local time, my Blog was also off-line.

I should also note that this minor interruption to my service took place at a time, when most domestic users don’t use the Internet, but during which many customers are sleeping. Therefore, this would also have been an ideal time by conventional standards, for my ISP to carry out any maintenance they had to carry out.

But nevertheless, I apologize to any readers for the fact that during this brief interval in time, they would not have been able to access my site.



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Just Created a Working Instance of TinyMCE

One of the more-interesting features of JavaScript in years gone by, was the in-browser HTML editor named ‘TinyMCE’. What this scriptlet does, is run on the browser, and allow people to edit the contents of a <textarea>, in WYSIWYG style, for submission to an arbitrary Web-application.

For me, this piece of JavaScript has little use. Other Web-applications of mine, already give me HTML editing which is rich enough, not to depend on TinyMCE. But there has been a facet of this scriptlet, which has irked beginning-users and Web-designers so far, which is that by default, it offers no ‘Save’ Menu-entry. The reason it does not is twofold:

  1. TinyMCE is meant to be integrated into some more-complex Web-page, where its input is also given a defined purpose, and
  2. By itself, this scriptlet just runs on the browser, from where it has no privilege to store its edited contents anywhere, neither on the server, nor on the client-machine running the browser.

And so some people have wondered, how they could exploit this amazing technology, just to save the edited HTML locally, to the hard-drive of the computer running the browser. And there are many possible ways to solve that problem, out of which I’ve just implemented one:

It’s possible to add a ‘Submit’ button, which sends the edited content to the server, which can in turn display it as a Web-page, that the user can save to his hard drive, using the “Save Page As…” Menu-command belonging to his browser. I cannot think of a solution that would be easier. However, if somebody wanted to use this mechanism, then next, he’d also need to open the .HTML-File saved to his hard-drive, and edit out the parts of it, that make it a Web-page, thus editing the saved HTML-File down to just the part that displays between the <body>…</body> tags.


(Update 2018/08/13 : )

Because this example of JavaScript sends the text to my server, which echos it back to the browser, I suppose that in theory I could reprogram my CGI-script, to keep a complete record of all the text-fragments submitted. But in practice, I see no point in doing so, and therefore also keep no record of what has been typed.

In addition, because I’ve suggested the URL as an ‘httpS://’ URL, a Secure Socket Layer gets used, so that No user will need to worry about the communication itself, to and from my server, being monitored by any third party.



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About how I won’t be doing any ‘ASL’ computing soon.

There exists an Open-Source code library named ‘ASL’, which stands for “Advanced Simulation Library“. Its purpose is to allow application-designers who don’t have to be deep experts at writing C++ code, to perform fluid simulations, but with the volume-based simulations running on the GPU of the computer, instead of on the CPU. This can also lead people to say, that ‘ASL’ is hardware-accelerated.

Last night I figured, that ‘ASL’ should run nicely on the Debian / Stretch computer I name ‘Plato’, because that computer has a GeForce GTX460 graphics card, which was considered state-of-the-art in 2011. But unfortunately for me, ‘ASL’ will only run its simulations correctly, if the GPU delivers ‘OpenCL’, version 1.2 or greater. The GeForce 460 graphics card is only capable of OpenCL 1.1, and is therefore no longer state-of-the-art by far.

Last night, I worked until exhausted, trying various solutions, in hopes that maybe the library had not been compiled correctly – I custom-compiled it, after finding out that the simulations were not running correctly. I also looked in to the possibility, that maybe I had just not been executing the sample experiments correctly. But alas, the problem was my ‘weak’ graphics card, that is nevertheless OpenGL 4 -capable.

As an alternative to using ‘ASL’, Linux users can use the Open-Source program-set called ‘Elmer‘. They run on the CPU.

Further, there is an associated GUI-application called ‘ParaView‘, the purpose of which is to take as input, volume-based geometries and arbitrary values – i.e., fluid states – and to render those with some amount of graphics finesse. I.e., ‘ParaView’ can be used to post-process the simulations that were created with ‘ASL’ or with ‘Elmer’, into a presentable visual. The version of ‘ParaView’ that installs from the package-manager under Debian / Stretch, ‘5.1.x’ , works fine. But for a while last night, I did not know whether problems that I was running in to were actually due to ‘ASL’ or to ‘ParaView’ misbehaving. And so what I also did, was to custom-compile ‘ParaView’, to version 5.5.2 . And if one does this, then the next problem one has, is that ParaView v5.5.2 requires VTK v7, while under Debian / Stretch, all we have is VTK v6.3 . And so on my platform, version 5.5.2 of ParaView encounters problems, in addition to ‘ASL’ encountering problems. And so for a while I had difficulty, identifying what the root causes of these bugs were.

Finally, the development branch, custom-compiled version of ‘Elmer’ and package-manager-installed ‘ParaView’ v5.1.x will serve me fine.



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Power failure tonight, downtime.

This evening, Montreal experienced a forecast, severe thunderstorm. But what could not be forecast with certainty, was whether the power would fail, in my exact neighborhood. In fact, it did.

I take the somewhat unusual approach, of hosting my Web-site, and therefore also this blog, on my PC at home. The availability of this blog can therefore not be any better, than the availability of my PC, to the Internet. Therefore, this site and blog were briefly offline, from about 19h00 until 20h00. I apologize for any inconvenience to my readers.



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