tryGit: it’s the teach, not the tech.

I picked up a link to a free online course from a recent Linux Voice podcast. I tried the course and wasn’t really impressed with it. The interface is nice, with an embedded virtual terminal to let you practice typing in the commands but the pedagogy is pretty weak. There’s nothing in the presentation that indicates that the designers understand how to construct understanding: all this lovely bit of code is doing is rehearsing a list of commands (and there’s even a click-once shortcut if you can’t be bothered actually typing). It’s more of a checklist than a course. It would be easy to turn it into a really effective bit of online learning with the addition of some better structure and graphics, and maybe a little assessment for learning. A shame, really, as it is clearly a loss leader to sell the Code School itself: I am in the market for some good quality online learning in their area, but I’m not likely to look any further at their catalogue.

ownCloud installation on Centos 7

For some time, I’ve wanted to have a calendaring tool independent of Google Calendar, which has become a central tool to my productivity and a source of concern as to how much data profiling results from it.

This afternoon, I installed the open source ownCloud file storage, calendar and contacts suite on my Centos VPS. It was a straightforward exercise:

  • Create a subdomain on the server and switch it to use PHP 5.6. Add /dev/urandom to open_basedir in php settings.
  • Make a data folder behind the web root, chowned to the web user.
  • Create a MySQL database for the ownCloud service.
  • In the web root folder, get the software:

curl -O https://download.owncloud.org/community/owncloud-10.0.3.tar.bz2

  • Check the MD5 hash, chown and extract. Copy the extracted files into the root folder (be careful to include dotfiles, e.g. cp owncloud/* . and cp owncloud/.* .)
  • Visit the domain to configure the installation.

What this server now provides is an independent calendar service, contacts, and secure file storage, at no additional cost and under my own secure control.

Migrating from AudioBoom

I’ve been podcasting using Audioboo (now Audioboom) since 2011 and supported the service by paying for a podcaster subscription for much of that time. Audioboom introduced a new pricing structure that I can’t sustain so I need to migrate to a new solution.
Using my LAMP server, which has bandwidth capacity for my podcasts, I set up a new subdomain on http://podcast.cullaloe.net and installed podcastgenerator 2.6. I uploaded a selection of episodes over FTP and used the import function in the admin interface (I had to change the timestamp using touch -t yymmddhhmm.ss filename.mp3 for each episode to get them into the right time order) finally editing in the description for each show.
For the most part, my episodes had embedded images in the mp3 file, but where they did not, I thought about having to edit the ID3 tags. I read about a method for avoiding this which includes posting an image (say, 300×300) for each track within the long description field in the admin interface of the new software, but this doesn’t seem to work. There’s a command line way to pull an image into an .mp3 file which sometimes works as an alternative:
ffmpeg -i input.mp3 -i cover.png -map 0:0 -map 1:0 -c copy -id3v2_version 3 -metadata:s:v title="Album cover" -metadata:s:v comment="Cover (Front)" out.mp3
If that doesn’t work, you can just drop an appropriate jpg/png in the images folder of the same name as the episode audio file.
The iTunes podcast feed was easily updated by visiting https://podcastsconnect.apple.com/  and pointing to the new feed. Note that podcast artwork must now be between 1400 x 1400 and 3000 x 3000 pixels, JPG or PNG, in RGB color space, and hosted on a server that allows HTTP head requests. The iTunes podcast updated overnight without any difficulty.
Finally, I emailed audioboom to request they apply a 301 or iTunes <itunes:new-feed-url/> redirect to the old feed (pointing to the new one).

Global Search for Moodle on Centos

My students are using a Moodle VLE to access resources and teaching materials and it became evident that some kind of global search function would help them find things quickly, especially later in the programme when they come to write their assignments.

I’m running Moodle on a CentOS 7.3 virtual private server with Plesk Onyx. The server hosts several other sites running WordPress, bespoke PHP and some other bits and pieces including the usual mail services. Some of the containers require the OS-standard PHP5.4 but a recent upgrade to Moodle 3.3 required me to switch the container to PHP 7.0.

Installing Global Search was a little tricky because of the multiple PHP versions running on the server, but I eventually figured it out to these key steps:

Install the Solr Server

$ cd /opt
$ wget http://apache.mirrors.nublue.co.uk/lucene/solr/6.6.0/solr-6.6.0.tgz
$ tar zxvf solr-6.6.0.tgz
$ cp solr-6.6.0/bin/install_solr_service.sh .
$ rm -rf solr-6.6.0
$ ./install_solr_service.sh solr-6.6.0.tgz
$ chkconfig solr on
$ su - solr -c "/opt/solr/bin/solr create_core -c moodle"

You should be able to visit http://your-domain.tld:8983 to verify the Solr server is running OK.

Secure the Solr Server

By default, Solr is open to the world. You might want to secure it by adding this at the end of /opt/solr/server/etc/webdefault.xml:

  <security-constraint>
   <web-resource-collection>
       <web-resource-name>Solr Administration</web-resource-name>
       <url-pattern>/*</url-pattern>
   </web-resource-collection>
   <auth-constraint>
       <role-name>solr-admin</role-name>
   </auth-constraint>
  </security-constraint>

  <login-config>
   <auth-method>BASIC</auth-method>
   <realm-name>Solr Administration</realm-name>
  </login-config>

Create a file in the same directory called realm.properties containing your chosen authentication details (matching the role above) in a single line:

admin: password, solr-admin

Finally, add this just before the last line in jetty.xml in the same directory:

<Call name="addBean">
 <Arg>
  <New class="org.eclipse.jetty.security.HashLoginService">
    <Set name="name">Solr Administration</Set>
    <Set name="config"><SystemProperty name="jetty.home" default="."/>/etc/realm.properties</Set>
    <Set name="refreshInterval">0</Set>
  </New>
 </Arg>
</Call>

Install the PHP Solr Extension

$ rpm -Uvh https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
$ rpm -Uvh https://mirror.webtatic.com/yum/el7/webtatic-release.rpm
$ yum install libxml2-devel pcre-devel libcurl-devel php70w-devel php70w-pear

You’ll need to build the extension using the right versions of phpize and php-config for your version of PHP, in my case, 7.0:

$ cd /opt
$ curl -O https://pecl.php.net/get/solr-2.4.0.tgz
$ tar zxvf solr-2.4.0.tgz
$ cd solr-2.4.0/
$ ../plesk/php/7.0/bin/phpize
$ ./configure --with-php-config=/opt/plesk/php/7.0/bin/php-config
$ make
$ make install
$ cp /opt/solr-2.4.0/modules/solr.so /opt/plesk/php/7.0/lib64/php/modules/
$ sudo service httpd restart

Visit the Site administration / ▶︎ Plugins / ▶︎ Search / ▶︎ Manage global search page in your Moodle installation to configure, index and enable the Solr Search Engine.

I am impressed with how quickly this has been used and appreciated by the students.

get_iplayer broken, version 3.00 available

For those of us who make use of the amazing get_iplayer program to obtain clips and other resources for classroom and other conveniences, it comes as a bit of a blow to find that in the past week or two, it has stopped working. Fortunately, there is a new version of the program available that with a little effort, gets the facility working again.

From the release notes:

The BBC removed all the XML-based data sources used by get_iplayer on 2017-04-26, breaking a lot of get_iplayer functionality. That functionality has been restored, but there are changes to be aware of – get_iplayer has not survived unscathed.

Phil Lewis and the team have (once again) done a fantastic job of quickly responding to changes in the way the BBC delivers its content. Many, many thanks to all the devs and hacks involved in this release.

Finally, my advice to users is to read the release notes carefully. You may also hit issues installing the new dependencies including Mojolicious and Perl as well as the cpan perl repository. Persevere, there is lots of useful advice out there. Finally, finally, the cache updates are much slower than before, although they are now only updated weekly.

Photographer portfolios – Koken

I set up a test site for a photography journal over at http://dev.cullaloe.net/koken/. I’ve been trying a number of alternatives and hosting options: koken is php software that runs on a Linux server over a mySql database and Apache. I happen to have one of those at dev.cullaloe.net.

So far, it looks like it has really nice features, including a tight integration with Adobe Lightroom that allows you to set up a direct publishing link. Most of the images on the site are reduced-size versions of some of my “good” photos.

I have found some bugs and irritations: the admin back-end fails completely from time to time, requiring clearing of api file cache over FTP. Themes are limited but they are quite pretty, I think, with development quite straightforward.

The original developer of this programme sold out to a new owner last year, I believe, but there seems to be some investment in bug fixing and development.

So far I don’t think it’s stable enough for a main online portfolio: you should probably just buy yourself a 500px Awesome membership for that and use the portfolio feature of that site.

Learn code

codeOver fifty years ago, my father was a US Air Force signals operator: he, like any other professional in communication, had to learn the languages of communication, command and control. I still have the LP (long-playing record, what the kids call “vinyl” now, although these weren’t vinyl) record set that he listened to as he learned Morse Code.

Today’s young people live in a world of communication and it is increasingly important for them – and all users – to at least have an appreciation of the languages used by the systems that pervade our modern lives. Learning to code – and the computational thinking that goes with it – is fun and interesting as well as being intellectually good for you. It’s also potentially lucrative: coding skills are at a premium, wherever you are in the world. While there is still a need for certain people to know Morse Code, there are many other languages to know about: from the languages of data to the logic of a sick (sic) 3D immersive games experience.

I have carried a link to CodeCademy on this site for some time because they offer some excellent resources and courses for people to learn how to code. I have used some of them myself and recommend them highly. If you’re not sure where to start, there is  a visual overview of the main programming languages and possible benefits of learning each one to help you make an informed decision. You can find it here: http://wiht.link/learncodeguide.

DISCLAIMER: I am not connected with Codecademy and have received no financial or other incentive to write this post. The infographic is not Codecademy’s and includes links to other free online places where you can learn. It’s just a good idea and a good place to get started. Get on with it!

GNU PSPP on OSX Yosemite

I have a project I’m working on that requires the use of a data analysis tool like IBM’s SPSS but at about six thousand dollars per year, it’s a little out of reach. There is an open source project, fortunately, that provides all the functionality I need for a lot less.

PSPP is, according to the project website:

“…designed as a Free replacement for SPSS. That is to say, it behaves as experienced SPSS users would expect, and their system files and syntax files can be used in PSPP with little or no modification, and will produce similar results (the actual numbers should be identical). The number of variables and cases is limited only by the computer architecture.”

There are a number of ways of getting PSPP depending on your operating system: I am a Mac OSX user running 10.10.5 Yosemite so installed it using MacPorts. As this is a brand new machine I’m installing it on, I needed to install MacPorts first: download and run the install package from the download page, update and then run the install (you need super user privilege):

$ sudo port selfupdate
$ sudo port install pspp

This will give you a working PSPP from the command line. If you want to use the graphical user interface over PSPP, known as PSPPIRE, you’ll need to update your X11 DISPLAY driver by downloading and installing XQuartz which is a community produced X-window server assisted but not supported by Apple. Once you’ve installed Quartz, you’ll need to log out and in again to update the DISPLAY environment. Once this is done you can launch the GUI version of PSPP from the command line:

$ sudo psppire

This allows you to work with your SPSS data sets and command files almost without modification.

Hello, World! Nice HAT.

Hello World!
Hello World!
Hello World!

For those of you trying to get to grips with the Raspberry Pi’s Astro-Pi Sense HAT… wait, what?

The Raspberry Pi is the amazing, powerful and compact computer-on-a-board that has got children of all ages around the world coding and investigating computational thinking. For less than fifty bucks, this machine includes a fast processor, a decent amount of RAM and USB, Ethernet and HDMI interfaces that let you connect it up to a TV and keyboard and do almost anything you can do on machines twenty times the price (like write this post, for example). If, like me, you like things tidy, you can add a box to put it in and if, like me, you’re a physics teacher, you can add on a sense HAT (Hardware Attached on Top) that is exactly the same as the kit to be used by Astronaut Tim Peake on the International Space Station to conduct experiments in space using the many sensors on board the HAT.

The whole kit cost me £75 including power supply and SD card with operating system (Raspbian – a version of Debian Linux) software pre-installed.

The setting up is simple and step-by-step, I got it working as a stand-alone machine before installing the Sense HAT. I had to take a knife to the official Raspberry Pi box once the HAT was added to the Pi board – it almost fits but just needs a little adjustment near the corner of the lid to make it snap into place. There are plenty of resources on the web to help you get started but development has taken place at such a pace that some of the guides don’t quite match the installed software. The Getting Started with the Sense Hat page at raspberrypi.org is no exception. There is a simple “Hello World!” program:

from sense_hat import SenseHat
sense=SenseHat()
sense.show_message("Hello, World!")

On my Pi 3B, I got an error at this point:

Traceback (most recent call last):
 File "/home/pi/hw.py", line 1, in <module>
 from sense_hat import SenseHat
 File "/usr/lib/python3/dist-packages/sense_hat/__init__.py", line 2, in <module>
 from .sense_hat import SenseHat, SenseHat as AstroPi
 File "/usr/lib/python3/dist-packages/sense_hat/sense_hat.py", line 14, in <module>
 from PIL import Image # pillow
ImportError: No module named PIL

This was because there was a step missing from the sense-HAT installation instructions which should have read:

sudo apt-get install sense-hat
sudo pip-3.2 install pillow

The second line was omitted, leading to the above error. Once the pillow module was installed OK, running the test python script above produced the results I was looking for (see picture). There is a lot of decent documentation at pythonhosted.org that I hope to take a look at in order to get some ideas for physics teaching using the sensors in my new HAT. I’m loving the sense of really playing (and learning) with computers: those of you old enough will remember the same joy of getting a BASIC program to run properly on your BBC or ZX Spectrum. Suddenly, computers are fun again.