Technology Tales

WordPress.com and user registration

Technical considerations regarding the discussion aspect of blogging

When making a start in the world of blogging, there are so many things to consider that you almost need a trial run first to learn the lingo. In fact, getting up to speed by using a service like that offered by Blogger or WordPress.com seems a very sensible starting point. Even so, the business is like building a house in that you only really know what you are doing after you have done the deed and made all the mistakes. That is particularly true when you go down the self-administered blog route. For starters, it’s so easy to pick the wrong domain name or hosting provider. Selecting your blogging software is the next step, but that may not be so tricky; WordPress does a reasonable job and there’s always Movable Type, Expression Engine, Drupal (yes, really) or Habari.

That mention of blogging software brings me to something that I encountered recently: commenting functionality. I am coming around to the idea that this is probably something that needs to be considered up front because of the nature of blogging. After all, anyone who reads The Blog Herald regularly should be familiar with the idea of blogging conversations and that means that the technology to make it happen should be easy for visitors to use and easy for bloggers to administer. However, the two can collide. For one thing, there are a myriad of choices available to the blogger and the blight of comment spam is ever pervasive and growing.

When it comes to comment spam, it is best to realise that there are two sources of responses to a blog post: visitor comments or trackbacks (pingbacks?) from other blogs. I reckon that the latter is probably the channel where most of the detritus travels and various anti-spam solutions are on offer to curb its spread. Names from the WordPress world like Akismet, Spam Karma, Simple Trackback Validation and Bad Behaviour come to mind. The former can also be used, particularly when the unscrupulous make use of low-cost labour in low-cost countries, and that’s when the thorny questions of user registration and CAPTCHA‘s arise. There is something to be said for not going to extremes with these and just sticking with less onerous rules and filtering on the server side.

I must admit to having staggering into forcing visitors to register prior to adding a comment and then making them log in thereafter. I think that it’s for security reasons, but WordPress creates a password and then sends it to the person who is registering rather than displaying on a web page. That can create another problem: what happens if the email fails to arrive? In the last week, this has happened with a visitor to my hillwalking blog and there could be a number of reasons for the non-arrival of the relevant email. One is ironic: being an automated email, it gets stuck in the spam filters of the recipient’s mailbox and so never gets to them. It could also be a bug with WordPress itself (I have raised a ticket and I am awaiting what Automattic might have to say to it) or a consequence of some setting made by a hosting provider. All of that makes it hard to track down the cause of the issue but it kicks off other thoughts as to its resolution. One is to remove the needed for registration and logging in the first place, but there are third-party services that may help too. The former has turned out to be the case for this blog and it seems to be performing well enough so it is an acceptable option.

When it comes to using third-party comment handling systems, what needs to be considered is how well they work with your blog. For instance, I gave Disqus a quick whirl and soon realised that I needed to update the themes for my WordPress blogs if I were to use it on an ongoing basis. Otherwise, it worked fine but I was left wondering if it would have been better to have brought it in when I started a blog rather than part way through and with comments made using the existing WordPress functionality. There’s also Intense Debate and I am almost certain that there are more like it but I’ll be sticking with what WordPress offers for now. The theme for my hillwalking blog has been modified to allow prospective commenters to get in touch with me if they are having problems. That is only an interim approach while I consider what the way forward will be.

Getting custom Python imports to work in Visual Studio Code

While I continue to use Spyder as my preferred Python code editor, I also tried out Visual Studio Code. Handily, this Integrated Development Environment also has facilities for working with R and Julia code as well as MarkDown text editing and adding the required extensions is enough for these applications; it helps that there is an unofficial Grammarly extension for content creation.

My Python code development makes use of the Pylance extension and it works a little differently from Spyder when it comes to including files using import statements. Spyder will look into the folder where the base script is located but the default behaviour of Pylance is that it looks in the root path of your workspace. This meant that any code that ran successfully in Spyder failed in Visual Studio Code.

The way around this was to add the required location using the python.analysis.extraPaths setting for the workspace. That meant opening Settings by navigating to File > Preferences > Settings in the menu system and entering python.analysis.extraPaths into the search box. That took me to the section that I needed and I then clicked on Add Item before entering the required path and clicking on the OK button. That was enough to fix the problem and all worked as it should after that.

Using multi-line commenting in Perl to inactivate blocks of code during testing

Recently, I needed to inactivate blocks of code in a Perl script while doing some testing. This is something that I often do in other computing languages so I sought the same in Perl. To do that, I need to use the POD methodology. This meant enclosing the code as follows.

=start

<< Code to be inactivated by inclusion in a comment >>

=cut

The =start line could use any word after the equality sign but it seems that =cut is needed to close the multi-line comment. If this was actual programming documentation, then the comment block should include some meaningful text for use with perldoc but that was not a concern here since the commenting statements would be removed afterwards anyway and it is good practice not to leave commented code in a production script or program to avoid any later confusion.

In my case, this facility allowed me to isolate the code that I needed to alter and test before putting everything back as needed. It also saved time since I did not need to individually comment out every executable line because multiple lines could be inactivated at a time.

SAS Data Step Hash Objects and Memory

Using hash objects in SAS data step code offers some great advantages from the speed point of view; having a set of data in memory rather than on disk makes things much faster. However, that means that you need to keep more of an eye on the amount of memory that’s being used. The first thing is to work out how much memory is available and it’s not necessarily the total amount installed on the system or, for that matter, the amount of memory per processor on a multi-processor system. What you really need is the number, in bytes, that is stored in the XMRLMEM system option and here’s a piece of code that’ll do just that:

data _null_;
mem=getoption('xmrlmem');
put mem;
run;

The XMRLMEM is itself an option that you can only declare in the system call that starts SAS up in the first place and there are advantages to keeping it under control, particularly on large multi-user servers. However, if your hash objects start to exceed what is available, here’s the sort of thing that you can expect to see:

ERROR: Hash object added 49136 items when memory failure occurred.
FATAL: Insufficient memory to execute data step program. Aborted during the EXECUTION phase.
NOTE: The SAS System stopped processing this step because of insufficient memory.
NOTE: SAS set option OBS=0 and will continue to check statements. This may cause NOTE: No observations in data set.

Those messages are a cue for you to learn to keep those hash objects and to only ever make them as large as your memory settings will allow. Another thing to note is that hash objects are best retained for rather fixed data volumes instead of ones that could outgrow their limits. There’s a certain amount of common sense in operation here but it may be that promoters of hash objects don’t mention their limitations as much as they should. If you want to find out more, SAS have a useful paper on their website and the their Knowledge Base has more on the error messages that you can get.

Selecting SAS code in the Program Editor on UNIX

Here’s a possible bugbear with programming using the SAS Display Manager in UNIX, selecting sections of code and running them. In the installations that I have encountered, the mouse selection is not retained so the code selection cannot be run. There is a fix for this and it is not the most obvious. Going to the Preferences dialogue box (Tools > Options > Preferences… from the menu bar) and selecting the Editing tab brings up the screen below:

Ensuring that "Automatically store selection" is switched off, as shown above, will allow one to select and submit sections of code from a SAS program like what is normal practice with Windows SAS. It isn’t an obvious solution but it does the trick for me.

Another way to look through WordPress code

At times in the past, I have complained about there not being sufficient documentation of the actual code used in WordPress itself. True, there is the venerable Codex but that can be incomplete and any extra help is always useful. Peter Westwood (a.k.a westi) has generated documentation from the code itself and put it up on the web for all to peruse. While we are on the subject of information on the more advanced aspects of WordPress, blogs by Mark Jaquith and Andrew Ozz are also worth a look. As the cliché goes, every little helps…

New domain name

I have registered the domain technologytales.com for this blog yesterday and have since got the DNS configuration completed. I used Easily.co.uk for the registration; they also host my other domain name and have done so since I first registered it. Easily allowed me to transfer to the WordPress.com namespace servers and $10 secured the rest of the setting up and $10 every year at renewal time with keep things in place. There is more about doing all of this on the WordPress FAQ.

Learning about Oracle

Installing VMware Player 4.04 on Linux Mint 13

Curiosity about the Release Preview of Windows 8 saw me running into bother when trying to see what it’s like in a VirtualBox VM. While doing some investigations on the web, I saw VMware Player being suggested as an alternative. Before discovering VirtualBox, I did have a licence for VMware Workstation and was interested in seeing what Player would have to offer. The, it was limited to running virtual machines that were created using Workstation. Now, it can create and manage them itself and without any need to pay for the tool either. Registration on VMware’s website is a must for downloading it though but that’s no monetary cost.

One I had downloaded Player from the website, I needed to install it on my machine. There are Linux and Windows versions and it was the former that I needed and there are 32-bit and 64-bit variants so you need to know what your system is running. With the file downloaded, you need to set it as executable and the following command should do the trick once you are in the right directory:

chmod +x VMware-Player-4.0.4-744019.i386.bundle

Then, it needs execution as a superuser. With sudo access for my user account, it was a matter of issuing the following command and working through the installation screens to instate the Player software on the system:

sudo ./VMware-Player-4.0.4-744019.i386.bundle

Those screens proved easy for me to follow so life would have been good if that were all that was needed to get Player working on my PC. Having Linux Mint 13 means that the kernel is of the 3,2 stock and that means using a patch to finish off the Player installation because the required VMware kernel modules seem to silently fail to compile during the installation process. This only manifests itself when you attempt to start Player afterwards to find a module installation screen appear. That wouldn’t be an issue of itself were it not for the compilation failure of the vmnet module and subsequent inability to start VMware services on the machine. There is a prompt to peer into the log file for the operation and that is a little uninformative for the non-specialist.

Rummaging around the web brought me to the requisite patch and it will work for Player 4.0.3 and Workstation 8.0.2 by default. Doing some tweaking allowed me to make it work for Player 4.04 too. My first step was to extract the contents of the tarball to /tmp where I could edit patch-modules_3.2.0.sh. Line 8 was changed to the following:

plreqver=4.0.4

With the amendment saved, it was time to execute the shell script as a superuser having made it executable before hand. This can be accomplished using the following command:

chmod +x patch-modules_3.2.0.sh && sudo ./patch-modules_3.2.0.sh

With that completed successfully, VMware Player ran as it should. An installation of Windows 8 into a new VM ran very smoothly and I was impressed with performance and responsiveness of the operating system within a Player VM. There are a few caveats though. First, it doesn’t run at all well with VMware Tools so it’s best to leave them uninstalled and it doesn’t seem to need them either; it was possible to set the resolution to the same as my screen and use the CTRL+ALT+ENTER shortcut to drop in and out of full screen mode anyway. Second, the unattended Windows installation wasn’t the way forward for setting up the VM but it was no big deal to have that experiment thwarted. The feature remains an interesting one though.

With Windows 8 running so well in Player, I was reminded of the sluggish nature of my Windows 7 VM and an issue with a Fedora 17 one too. The result was that I migrated the Windows 7 VM from VirtualBox to VMware and all is so much more responsive. Getting it there took not a little tinkering so that’s a story for another entry. On the basis of my experiences so far, I reckon that VMware Player will remain useful to me for a little while yet. Resolving the installation difficulty was worth that extra effort.