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Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for 2018

Micro SD Cards for Development Boards – Classes, Tools, Benchmarks, Reliability, and Tips & Tricks

Posted by jpluimers on 2018/11/09

Last year I bumped into a great article about the state of the art on [WayBackMicro SD Cards for Development Boards – Classes, Tools, Benchmarks, Reliability, and Tips & Tricks.

I wonder what has changed by now.

Some references from the above article:

–jeroen

Via: [WayBack] Informations about (micro) SD cards specifically geared towards their use in development boards such as the +Raspberry Pi+Samsung Electronics and +SanD… – Jean-Luc Aufranc – Google+

Posted in Flash-memory, Power User, SD/miniSD/microSD/MMC, Storage | Leave a Comment »

Load testing a web server on Windows using the ApacheBench benchmark tool from Apache

Posted by jpluimers on 2018/11/08

Based on:

  1. Download the most recent x64 Apache binaries for Windows from [WayBackApache VC15 binaries and modules download (at the time of writing: https://www.apachelounge.com/download/VC15/binaries/httpd-2.4.34-win64-VC15.zip )
  2. Extract recursively to D:\bin
  3. Run the UltrawareController locally
  4. Run D:\bin\httpd-2.4.34-win64-VC15\Apache24\bin\ab.exe -n 1000 -c 10 http://localhost:8000/foo

This will run the ab Apache benchmark tool with 1000 connections using 10 threads all doing the same http GET request at http://localhost:8000/foo

If you want to test TLS (https) connections, then you need to use the abs tool in the same directory as the ab tool supports http-only (when you still try, you get the message SSL not compiled in; no https support as explained in [WayBack] Add https support to Apache Bench on Windows – Stack Overflow).

Download location via [WayBack] windows – Is there any link to download ab Apache benchmark – Stack Overflow:

There are many more command-line parameters documented at [WayBack] ab – Apache HTTP server benchmarking tool – Apache HTTP Server Version 2.4, this is the summary:

Synopsis

ab [ -A auth-username:password ] [ -b windowsize ] [ -B local-address ] [ -c concurrency ] [ -Ccookie-name=value ] [ -d ] [ -e csv-file ] [ -f protocol ] [ -g gnuplot-file ] [ -h ] [ -Hcustom-header ] [ -i ] [ -k ] [ -l ] [ -m HTTP-method ] [ -n requests ] [ -p POST-file ] [ -Pproxy-auth-username:password ] [ -q ] [ -r ] [ -s timeout ] [ -S ] [ -t timelimit ] [ -Tcontent-type ] [ -u PUT-file ] [ -v verbosity] [ -V ] [ -w ] [ -x <table>-attributes ] [ -Xproxy[:port] ] [ -y <tr>-attributes ] [ -z <td>-attributes ] [ -Z ciphersuite ] [http[s]://]hostname[:port]/path

Via: [WayBack] apache – ab load testing – Stack Overflow

jeroen

Posted in Communications Development, Development, HTML, HTTP, Internet protocol suite, Software Development, Web Development | Leave a Comment »

Relay Switch Circuit and Relay Switching Circuit

Posted by jpluimers on 2018/11/08

Via yesterdays post on a bench power supply fabricated from an ATX power supply, I found this very interesting set of relay switching circuits:

Electronics Tutorial about the Relay Switch Circuit and relay switching circuits used to control a variety of loads in circuit switching applications

[WayBackRelay Switch Circuit and Relay Switching Circuit

The images below are from that site. Note the BC337 and BC109 have different voltage/power specs. See [WayBackBC337/BC109 datasheet & application note – Datasheet Archive.

–jeroen

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Posted in Development, Hardware Development | Leave a Comment »

Build Lambda Expressions Dynamically – CodeProject

Posted by jpluimers on 2018/11/08

On my research list: [WayBackBuild Lambda Expressions Dynamically – CodeProject

GitHub Source: dbelmont/ExpressionBuilder

–jeroen

Posted in .NET, Development, Software Development | Leave a Comment »

Reminder to self: make a start for an XSD that validates Delphi dproj files

Posted by jpluimers on 2018/11/07

Below are a few interesting things from this thread [WayBack] Any idea why Delphi (At least since Seattle) does this to Dproj filesand… – Tommi Prami – Google+.

It’s likely that the WordPress system deleted parts between angle brackets because it thinks it’s invalid HTML and WordPress is PHP.

Anyhow: maybe by now I’ve found time for creating an XSD for .dproj files in addition to the one I mentioned yesterday for the .groupproj files: Validating a nested XML element with an empty namespace using XSD – Stack Overflow.

Oh and in the mean time for various Delphi versions, there is a (binary, because it uses some commercially licensed parts) [WayBackDproj changed or not changed? Normalize it! | The Art of Delphi Programming.

Files and directories I need to research:

In the mean time, QualityPortal indicates that:

Achim Kalwa:
That is a long living bug: https://quality.embarcadero.com/browse/RSP-11308
Still exists in Berlin Update 2.

Jeroen Wiert Pluimers
For more than a decade, the IDE rewriting dproj files in different order/indentation/spacing, properties appearing/disappearing in DFM files and writing DFM files despite no changes have driven me even more nuts than I was.

Walter Prins
+Jeroen Wiert Pluimers Yes. Given that .dproj is XML I’ve been almost annoyed enough to look at making some kind of pre-checkin script to force sort things to try and avoid the issue. Almost… Edit: Ah, just checked that RSP, which references this: https://github.com/joshkel/RadCli Seems someone has already done it.

Lübbe Onken
Did you try tidy_proj +Walter Prins? For me it fails with a “Unicode Encode Error” when I try to write an output file. In my case this is caused by German umlauts in the excluded bpl section descriptions. Changing the umlauts to something low-ascii allows tidy_proj to finish.

Walter Prins
+Lübbe Onken No, but I have just done so. Unicode bites again. To fix that error, change line 125 from:

print(proj.toxml())

to:

print(proj.toxml().encode(‘utf-8’))

Note: This will likely not display correctly if you allow the output to go to the console but will ensure it is correct if redirected back to file.

Edit: Ha, I was about to go report this issue ad suggest this fix, but I see you’ve already suggested essentially the same fix. ;)

Jeroen Wiert Pluimers’s profile photo
Jeroen Wiert Pluimers
+Walter Prins interesting tool! Do you know of a tool that can downgrade .dproj files so you can use them with older Delphi versions? (the opposite of what the IDE does)?

Or someone that has written more than my XSD on .dproj files? My one is so small that’s hardly a real attempt. https://wiert.me/2013/08/31/delphi-first-try-on-an-xsd-for-groupproj-files/

Walter Prins
+Jeroen Wiert Pluimers No, but interesting idea. I suppose you’re probably aware that the JEDI JCL/JVCL takes a somewhat similar (ish) related approach, in that it generates project and package files that are compatible with every desired version of Delphi from minimalist (XML) template files. Every so often I think it might be worth looking whether one can re-use the code from there easily but haven’t gotten around to it. Always something else to do first. :/

Jeroen Wiert Pluimers
+Walter Prins no I didn’t. Where should I start reading on that minimalist template approach?

Walter Prins
+Jeroen Wiert Pluimers Sorry I see I missed out the word installer in my comment: It’s the Jedi JCL/JVCL installers that uses xml templates etc.

But the point stands: I guess it should be (perhaps) possible to reuse its infrastructure for ones own projects, though as I say I keep meaning to look into this but haven’t really done so.

(BTW I’m assuming you are familiar with the JCL/JVCL and in in particular their installers that bootstrap from source code? If not then perhaps my comments may not be that useful?)

Anyway, not sure if or where there’s particular documentation about this (kind of doubt it), but if you have the JCL/JVCL installed somewhere, then first of all have a look at the “xml” folders e.g. “<jclroot>\jcl\packages\xmls” and “<jvclroot>\jvcl\packages\xml”.

These files appear to define projects and packages in a seemingly abstract/somewhat minimal way using XML. This seemingly is then used to automatically produce .dproj and .dpk files which are placed in e.g. “<jclroot>\jcl\packages\dXX” and “<jvclroot>\jvcl\packages\dXX” where dXX corresponds to a folder for each of the supported Delphi versions and compiled/used during installation.

Having just looked into this briefly a bit further as a result of this conversation: Key units here (in the case of JVCL) seems to be “<jvclroot>\devtools\PackagesGenerator\PackageGenerator.pas”, “<jvclroot>\install\JVCLInstall\PackageUtils.pas” and “<jvclroot>\devtools\common\PackageInformation.pas” (used predictably by <jvclroot>\JVCLInstall.dproj)

(Additionally, having looked at this a bit more closely, it also appears that the JCL does not actually replace all or even most of its .dproj and .dpk files after all, but ships version specific .dproj and .dpk files in most cases, though the JVCL does appear to mostly do so. )

Edit: The JCL also has this interesting sounding unit “jclroot>\source\windows\JclMsBuild.pas” which appears to be an MSBuild project file parser…

–jeroen

Posted in Conference Topics, Conferences, Continuous Integration, Delphi, Development, Event, msbuild, Software Development, XML, XML/XSD, XSD | Leave a Comment »

Babelmark 2 online Markdown checker

Posted by jpluimers on 2018/11/07

Some markdown tools have their own page online allowing you to experiment with their rendering; [WayBack] markdown-it demo is one of them.

I was looking for a page showing the renderings of many engines in order to improve my markdown writing skills.

I found the [WayBackbabelmark2 online markdown checker, which works great.

  • It runs the markdown through various processors showing either the log with HTML produced, or a view of the rendered output.
  • It has one limitation: 1000 characters of markdown text so the markdown rendering servers will not get overloaded.

Documentation is at [WayBack] Babelmark 2 – FAQ.

In addition, this is also very useful: [WayBack] markdownlint demo Demo for [WayBack] GitHub – DavidAnson/markdownlint: A Node.js style checker and lint tool for Markdown/CommonMark files.

Note that the Visual Studio Code markdownlint support, uses the above markdownlint, which is a different one than the Ruby based [WayBack] GitHub – markdownlint/markdownlint: Markdown lint tool.

Both are far easier to use than [WayBack] GitHub – michelf/mdtest: Test suite for Markdown implementations.

Via

–jeroen

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Posted in Development, Lightweight markup language, MarkDown, Software Development | Leave a Comment »

How to Setup Chroot SFTP in Linux (Allow Only SFTP, not SSH)

Posted by jpluimers on 2018/11/07

I need to script this one day: [WayBackHow to Setup Chroot SFTP in Linux (Allow Only SFTP, not SSH)

–jeroen

Posted in *nix, Awk, bash, Communications Development, Development, Internet protocol suite, Power User, Scripting, Software Development, SSH, TCP | Leave a Comment »

Delphi: updating a (potentially non-existing) item in a generic TDictionary: use ExtractPair. Except in Delphi 2010/XE.

Posted by jpluimers on 2018/11/06

“Documented” in Delphi 2010, [Archive.is] Generics.Collections.TDictionary.ExtractPair – RAD Studio VCL Reference, and functioning bug-free since Delphi XE2, but still hardly documented, [Archive.is] System.Generics.Collections.TDictionary.ExtractPair – XE2 API Documentation is the easiest way to get a value out of a dictionary and updating it, even if it does not exist.

ExtractPair extracts the TPair<TKey, TValue> if it exists (and removes it from the dictionary) or returns a Default initialised one if not. Though Default is still not documented, you can find an example at [WayBack] How to properly free records that contain various types in Delphi at once? – Stack Overflow.

Example code for ExtractPair:

  FEceptionDictionary := TDictionary<TExceptionKey, Integer>.Create();

...

var
  ExceptionCountPair: TPair<TExceptionKey,Integer>;
begin
  TMonitor.Enter(FEceptionDictionary);
  try
    ExceptionCountPair := FEceptionDictionary.ExtractPair(ExceptObj.ClassType); // extracts and removed from dictionary!
    FEceptionDictionary.Add(ExceptionCountPair.Key, ExceptionCountPair.Value + 1); // use Value as count
  finally
    TMonitor.Exit(FEceptionDictionary);
  end;
end;

In Delphi 2010 and XE it was buggy (see [WayBack] QualityCentral 80947: TDictionary.ExtractPair Fails and creates memory leak via [WayBack] generics – Delphi TPair Exception – Stack Overflow), but since then it works fine, and now is properly documented:

[WayBack] System.Generics.Collections.TDictionary.ExtractPair – RAD Studio API Documentation

Returns the TPair<TKey,TValue> pair with the specified Key and [WayBackremoves the returned pair from a dictionary.

If the dictionary does not contain the specified Key, the returned pair contains a default TValue.

–jeroen

Posted in Delphi, Development, Software Development | 5 Comments »

Validating a nested XML element with an empty namespace using XSD – Stack Overflow

Posted by jpluimers on 2018/11/06

In a quest for making Delphi Group Project XML files (with extension .groupproj) validate with XSD, I had to find out about [WayBackValidating a nested XML element with an empty namespace using XSD – Stack Overflow.

I needed the XSD so I could import it in Delphi in order to write a good .groupproj file generator.

They are here:

And some more background posts are here:

–jeren

Posted in Delphi, Development, Software Development, XML, XML/XSD, XSD | 1 Comment »

Some Computerphile videos starring Professor Brian Kernighan

Posted by jpluimers on 2018/11/06

Most you probably know [WayBackProfessor Brian Kernighan or the YouTube channel Computerphile (sister channel of Numberphile).

He stars in about half a dozen of their videos giving a nice insight in his contributions to the field and how well he can explain things.

Full videos are below; these are the titles:

BTW: If you like those youtube channels, check out [WayBackBrady Haran – Video Journalist who produces similar channels as well.

–jeroen

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Posted in *nix, Awk, C, Development, Power User, Scripting, Software Development | Leave a Comment »