Catalyst IT Limited  
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21 October 2016

Kristina Hoeppner


Getting the hang of hanging out (part 2)

A couple of days ago I experienced some some difficulties using YouTube Live Events. So today, I was all prepared:

  • Had my phone with me for 2-factor auth so I could log into my account on a second computer in order to paste links into the chat;
  • Prepared a document with all the links I wanted to paste;
  • Had the Hangout on my presenter computer running well ahead of time.

Indeed, I was done with my prep so much in advance that I had heaps of time and thus wanted to pause the broadcast as it looked like it was not actually broadcasting since I couldn’t see anything on the screen. So I thought I needed to adjust the broadcast’s start time.

Hence why I stopped the broadcast and as soon as I hit the button I knew I shouldn’t have. Stopping the broadcast doesn’t pause it, but stops it and kicks off the publishing process.

Yep, I panicked. I had about 10 minutes to go to my session and nobody could actually join it. Scrambling for a solution, I quickly set up another live event, tweeted the link and also sent it out to the Google+ group.

Then I changed the title of the just ended broadcast to something along the lines of “Go to description for new link”, put the link to the new stream into the description field and also in the chat as I had no other way of letting people know where I had gone and how they could join me.

I was so relieved when people showed up in the new event. That’s when the panic subsided, and I still had about 3 minutes to spare to the start of the session.

The good news? We released Mahara 16.10 and Mahara Mobile today (though actually, we soft-launched the app on the Google Play store already yesterday to ensure that it was live for today).

19 October 2016

Kristina Hoeppner


Getting the hang of hanging out (part 1)

Living in New Zealand, far, far away from the rest of the world (except maybe Australia), means that I’m doing a lot of online conference presentations, demonstrations, and meetings. I’ve become well-versed in a multitude of online meeting and conferencing software and know what works on Linux and what doesn’t.

The latter always give me a fright as I have to start up my VM and hope for the best that it will not die on me unexpectedly. Usually, closing Thunderbird and any browsers helps free some resources in order to let Windows start up. I can only dream of a world in which every conferencing software also runs on Linux.

Lately, some providers have gotten better and make use of WebRTC technology, which only requires a browser but no fancy additional software or flash. Only when I want to do screensharing do I need to install a plugin, which is done quickly.

So for meetings of fewer than 10 people, I’m usually set and can propose a nice solution like Jitsi, which works well. In the past, my go-to option was Firefox Hello for simple meetings, but that was taken off the market.

But what to do when there may be more than 10 people wanting to attend a session? Then it gets tough very quickly. So I have been trialling Google Hangouts on Air recently after I’ve seen David Bell use them successfully. It looked easy enough, but boy, was I in for a surprise.

Finding the dashboard

At some point, my YouTube account was switched to a “Creator Studio” one and so I can do live events. Google Hangouts on Air are now YouTube Live Events and need to be scheduled in YouTube.

There is no link from the YouTube homepage to the dashboard for uploading or managing content. I’d have thought that by clicking on “My channel” that I’d get somewhere, but far from it. There is nothing in the navigation.

The best choice is to click the “Video Manager” to get to a subpage of the creator area. Or, as I just found out, click your profile icon and then click the “Creator Studio” button.

Finding the creator dashboard

Getting to the creator dashboard either via the “Video Manager” on your channel or via the button under your profile picture.

Scheduling an event

Setting up an event is pretty straight forward as it’s like filling in the information for a video upload just with the added fields for event times.

Unfortunately, I haven’t found yet where I can change the placeholder for the video that is shown in the preview of the event on social media. It seems to set it to my channel’s banner image rather than allowing me to upload an event-specific image.

So once you have your event, you are good to go and can send people the link to it. The links that you get are only for the stream. They do not allow your viewers to actually join your hangout and communicate with you in there and that’s where it gets a bit bizarre and what prompted me to write this blog post so I can refer back to it in the future.

Different links for different hangouts

There is the hangout link and the YouTube event link

Streaming vs. Hangout

There are actually two components to the YouTube Live event (formerly known as Google Hangout on Air):

  1. The Hangout from which the presenter streams;
  2. The YouTube video stream that people watch.

In order to get into the Hangout, you click the “Start Hangout on Air” button on your YouTube events page. That takes you into a Google Hangout with the added buttons for the live event. You are supposed to see how many people joined in, but the count may be a bit off at times.

In that Google Hangout, you have all the usual functionality available of chats, screensharing, effects etc. You can also invite other people to join you in there. That will allow them to use the microphone. The interesting thing is that you can simply invite them via the regular Hangout invite. You can’t give them the link to the stream as they would not find the actual hangout. And if you only give people the link to the Hangout but not the stream, nobody will be in the stream.

Finding the relevant links in the hangout

You can also get the two different links from the hangout. Just make sure you get the correct one.

The YouTube video stream page only shows the content of the Hangout that is displayed in the video area, but not the chat. The live event has its separate chat that you can’t see in the Hangout! In order to see any comments your viewers make, you need to have the streaming page open and read the comments there.

In a way, it’s nice to keep the Hangout chat private because if you have other people join you in there as co-presenters, you can use that space to chat to each other without other viewers seeing what you type. However, it’s pretty inconvenient as you have to remember to check the other chat. Dealing with separate windows during a presentation can be daunting. It would be nicer to see the online chat also in the hangout window.

Today I even just fired up another computer and had the stream show there, which taught me another thing.

Having the stream on another computer also showed me how slow the connection was. The live event was at least 5 seconds behind if not more. That is something to consider when taking questions.

The stream was also very grainy. I was on a fast connection, but the default speed was on the lowest setting nevertheless. Fortunately, once I increased the resolution on the finished video, the video did get better. I don’t know if you could increase the setting during the stream.

Last but not least, I couldn’t present in full-screen mode as the window wouldn’t be recognized. I’ll have to try again and see if it works if I screenshare my entire desktop as it would be nicer not to show the browser toolbars.

Not sharing of links

When you are not the owner of the stream, you cannot post URLs. I’m pretty sure that is to prevent trolls misusing public YouTube events to post links. However, it’s pretty inconvenient for the rest who want to hold meetings and webinars and share content. You can’t post a single link. Only I as organizer could post links. Unfortunately, I found that out only after the event as I was logged in under a different account.

Being used to many other web conferencing software, I’ve come to like the backchannel and the possibility to post additional material, which are in many cases links, so people can simply click on them. This was impossible in the YouTube live event as I was only a regular user. And even had I logged in with my creator account, which I’ll certainly do during the next session on Friday, nobody else would have been able to post a link. That is very limiting. I wish it were possible to determine whether links were allowed or not.

Editing the stream

Once the event was over today, I went back to the video, but couldn’t find any editing tools. I started being discouraged as I had hoped to simply trim the front and the back a bit from non-essential chatter and then just keep the rest of the video online rather than trimming my local recording that I had done on top of the online recording, encoding that and uploading it. Before I could get sadder, I had to do some other work, and once I came back to the recording, I suddenly had all my regular editing tools available and rejoiced. Apparently, it takes a bit until all functionality is at your disposal.

So I trimmed the video, which was not easy, but I managed. And then it did its encoding online. After some time, the shortened recording was available and I didn’t have to send out a new link to the video. 🙂

Summing up

What does that mean for the next live event with YouTube events?

  1. Click the “Creator Studio” button under my Google / YouTube profile to get to the editor dashboard easily.
  2. Invite people who should have audio privileges through the Hangout rather than giving them the YouTube Live link, which is displayed more prominently.
    • Co-presenters are invited via Hangout.
    • Viewers get the YouTube live link.
  3. Open the YouTube Live event with the event creator account in order to be able to post links in the chat on YouTube. Have both the Hangout and the YouTube Live event open so you can see the online chat of those who aren’t in the Hangout.
  4. Take into account that there is a delay until the content is shown on YouTube.
  5. Once finished, wait a bit until all editing features are available and then go into post-production.

Remembering all these things will put me into a better position for the next webinar, which is a repeat session of today’s and showcases the new features of Mahara 16.10.

Update: Learn some more about YouTube Live events from my second webinar.

14 October 2016

Jonathan Harker

Learning the contrabass trombone

Wessex Contrabass in F and Shires bass trombone, side by side.
Wessex Contrabass in F and Shires bass trombone, side by side.

I’ve recently acquired a Wessex contrabass trombone in F. It is pretty much a knock-off of the Thein Ben van Dijk model, and compared to this gold standard of contrabass trombone, this instrument is about an eighth of the price and a perfectly decent instrument. It plays really well throughout the range and the slide, valves and bell are all of high build quality, unlike the notorious Chinese-made instruments of the past.

But really, this post is just an excuse to test out a nifty music notation WordPress plugin. The shorthand it uses is ABC which is a bit quaint compared to Lilypond, but it seems to work well enough. For instance, take the first scale we might learn on a contrabass trombone:

The contrabass trombone in F only has six positions on the open slide instead of seven. Furthermore, only the first five are actually practical, unless you are Tarzan, so we can play the G on the first (D) valve in third position. While the A is also theoretically available in first position on the D valve, it is indistinct and slightly flat. Play that shit on the open slide in fourth. Good. Now, how about an excerpt from Ein Alpensinfonie by Richard Strauss:

Sounds good! Now, pop along to the NZSO performance in March 2017 to hear Shannon playing it, live in concert! In the meantime, here’s this exceprt by Berlin Philharmoniker:

11 October 2016

Kristina Hoeppner


Mahara Hui @ AUT recap

I’m playing catch-up and working my way backwards of my events. Yesterday, I wrote a bit about the NZ MoodleMoot on 5 October 2016. Just a day before that, AUT organized a local half-day Mahara Hui, Mahara Hui @ AUT 2016. Lisa Ransom and Shen Zhang from CfLAT (Centre for Learning and Teaching) were responsible for the event and did well wrangling everything and made all attendees feel welcome.

It was great to catch up with lecturers and learning technology support staff from AUT, Unitec and University of Waikato, and with a user from Nurseportfolio. We started the day out with introductions and examples of how people use Mahara.

Mahara in New Zealand tertiaries

At AUT, the CfLAT team trained about 630 students this academic year, in particular Public Policy, Tourism and Midwifery. Paramedics are also starting to use ePortfolios and can benefit from the long experience that Lisa and Shen have supporting other departments at AUT.

Linda reported that Mahara is now also being used in culinary studies in elective courses as well as degree papers. They use templates to help students get started, but then let them run with it. Portfolios are well suited for culinary students as they can showcase their work as well as document their creation progress and improve their work.

She also showcased a portfolio from a new lecturer who became a student in her area of expertise, going through a portfolio assignment with her students to see for herself how the portfolios worked and what she could and wanted to expect from her students. By going through the activity herself, she became an expert and now has a better understanding of the portfolio work.

John, an AUT practicum leader, who was new to AUT, came along to the hui and said that they were starting to use portfolios for their lesson plans and goals. Reflections are expected from the future teachers and form an important aspect. I’m sure we’ll hear more from him.

Sally from Nursing at AUT is looking at Mahara again, and the instructor could form connections directly with Unitec and Nurseportfolio, which is fantastic, because that’s what these hui are about: Connecting people.

JJ updated the group on the activities at Unitec. Medical imaging is going digital and looking into portfolios, and they also created a self-paced Moodle course on how to teach with Mahara effectively so that lecturers at Unitec can get a good overview.

Stephen from the University of Waikato gave an overview of the portfolio activities  at his university. Waikato still works with two systems, for education students becoming teachers, and the new Waikato-hosted Mahara site. Numerous faculties at Waikato now work with portfolios. If you’d like to find out more directly, you can watch recordings from the last WCELfest, in particular the presentations by Richard Edwards, Sue McCurdy and Stephen Bright. Portfolios will be used even more in the future as evidence from general papers will need to be collected in them by every student.

We also discussed a couple of ideas from a lecturer and are interested in other people’s opinion on them. One idea was to be able to share portfolios more easily in social networks and then see directly when the portfolio was updated and share those news again. The other idea was to show people who are interested in the portfolios when new content has been added. The latter is already possible to a degree with the watchlist. However, there students or lecturers still need to put specific pages on the watchlist first rather than the changes coming to them. The enhancements that Gregor is planning for the watchlist goes more in that direction.

Mahara 16.10

In a second part of the hui, I presented the new features of Mahara 16.10, and we spent a bit of time on taking a closer look at SmartEvidence.

I’m very excited that this new version will be live very soon and look forward to the feedback by users on how SmartEvidence works out for them. It’s the initial implementation. While it doesn’t contain all the bells and whistles, I think it is a great beginning to get the conversations started around use cases besides the ones we had and see how flexible it is.

Next hui and online meetings

If you want to share how you are using Mahara, you’ll have the opportunity to do so in Wellington on 27 October 2016 when we’ll have another local Mahara Hui, Mahara Hui @ Catalyst. From 5 to 7 April 2017, we are planning a bigger Mahara Hui again in Auckland. More information will be shared soon on the Mahara Hui website.

There will also be two MUGOZ online meetings on 19 and 21 October 2016 in which I’ll be presenting the new Mahara 16.10 features. You are welcome to attend either of these 1-hour sessions organized by the Australian Mahara User Group. Since the sessions are online, anybody can tune in.

22 September 2016

Catalyst Blog


Burning Samba with perf and FlameGraph

Samba implements many things, but in this case we look at Samba as an Active Directory DC.

In that role, Samba now has a quite credible implementation of the required protocols, and so is deployed in education, governments, large corporations and small businesses around the world.

One of the great things about our Samba users is the scale they are willing to push Samba to. With Samba now well established as a reliable solution, our enthusiastic users are now deploying it at larger and larger scales, and rightly expect that it continues to 'just work'.

The Samba team at Catalyst has been working to keep Samba performing to those expectations, and this blog will look at what we have achieved for the Samba 4.5 release.

It all started with two issues raised by our clients, which turned out to dovetail really well:
 - Samba replication performance with a large number of linked attributes
 - Samba runtime add/remove performance with linked attributes.

This post will examine how we addressed the first issue, in replication.

First, we worked to reproduce the situation found by the client: a domain with a large number of users, especially users in groups.  Due to the second issue especially, reproducing the situation took a long time. We pre-created such a database for re-use.

Next the replication operation was run under 'perf record'.  The linux perf/perf_events tools from the Main Page are a low overhead, sample-based profiling system. The system allows us to explore statistically, where our program time is spent.

Replicating the problem statement from the client, our domain has a larger number of group members, and these memberships are described as linked attributes in AD.  Under perf record, we ran 'samba-tool drs clone-dc-database' to emulate replication without making any
modifications to the domain.

To determine where the time is being spent, the output was then visualised with the FlameGraph tool by Brendan Gregg.

As you can see in this first image, Samba's handling of these is suboptimal in two ways:

 - A number of the processing steps are clearly being done in a tight loop (as GUID_compare() and ldb_val_equal_exact() are very fast routines when run only once.
 - The processing is done in ldb_transaction_commit, so this means it is with the database transaction lock held.  In this case no other process can make writes to the database while this processing is being undertaken.

One of the most helpful things about flame graphs is they are dynamic: they include JavaScript, and users can drill down into them, and use them as a map to investigate the source code.  We can follow from replmd_prepare_commit() down to ltdb_modify_internal(), and see the real problem:

Helpfully, described in the comment as O(n²), we need to avoid doing this processing.  In this case the solution was not a change to a better algorithm such as a merge sort, but to avoid the check entirely!

The difference this has made is quite clear as seen in the second flame graph (right). An entire tongue of flame has just vanished.  This graph also differs in that we changed the trace from being kernel-wide to just the client process, once it became clear that the CPU time is only problematic in the client.

We attacked the GUID_compare() stack next, with a simple change to apply the linked attributes earlier during the replication, so as to avoid building and so traversing a long list. Again, the results are quite dramatic.

However, there is still a problem: get_parsed_dns() is being called way too often, and it spends almost as much time cleaning up the memory allocated as doing actual work.

While this is certainly worth some attention, we left this particular line of attack, and instead focused on why the underlying routines are so expensive. This matters because while clearly overused, these routines are also used incredibly often in the rest of the codebase. We focused on why the NDR parsing of GUIDs and SIDs.  Both carried an incredibly high load for memory allocation compared to the work done, and so we added routines that perform NDR parsing without memory allocation.

We also examined why talloc calls, and particularly talloc_free() calls are so expensive, and talloc 2.1.8 contains these improvements.

After all this work, for this particular example, we can now do replication in around half the time previously taken!

19 September 2016

Catalyst Blog


Recurring Payments with Drupal Commerce and PayPal

by Andrew Boag

During the build of one our Catalyst as-a-Service offerings – CourseBank – we implemented a recurring credit card billing solution, which allows customers to fully provision a premium account.

Catalyst has been involved in a number of credit card and mobile payment solutions over the last 15 years. Best practices have changed a lot, and there are now many more payment gateways on the market.

It has always been considered a dangerous practice to retain a copy of a client's credit card details in your own application database. It makes you, the provider of the solution, potentially liable for the wholesale theft of credit card details.  In the past, it wasn't unheard of to implement recurring payments by simply storing the credit card details inside your application and firing off an API call with a payment request every month. Not something that Catalyst recommends.

These days, the initiatives in the Payment Card Industry Data Security Standard (implemented in 2004) mean that there are concrete rules systems need to comply with for the protection of card holder data. For the most part, these initiatives benefit both retailer and customer, reducing the overall risk of credit card theft and fraudulent transactions.

The safest and most usual model when integrating credit card payments into your online store is to not “see” or process the credit card details at all. Instead, integrate with an external payment gateway that processes the entire transaction in a workflow.

We suggest the following:

  1. After the customer has selected their product in your web store they click on “Proceed to Checkout” link. This takes them to the external payment gateway.
  2. At this point the customer has left the web store application. They're now located at a payment gateway (e.g. PayPal) and see the items they are purchasing again, with a total cost.
  3. The customer enters their credit card details and confirms the purchase. This may include some identity validation via their bank such as an SMS being sent to the card holder with a code that they must enter.
  4. Once payment is completed, the customer is forwarded back to the online store with a “Payment Successful” message.
  5. The customer may also receive payment notifications by email after the transaction.

Catalyst's Recurring Payment Requirements

Our CourseBank product is a traditional online service offering. Customers provide their credit card details only once during sign up. Then they are billed every month until they cancel the service.

Catalyst chose PayPal as our payment gateway partner.

Why PayPal?

Catalyst made this choice based on investigations, experimentation and experience. The PayPal service offering gave us a suitable feature set to implement recurring payments, and to integrate this with our Drupal 7 application. We use Drupal as the gateway for subscription, payment workflow and ongoing account management.

Conveniently, it is PayPal that schedules and handles the recurring payments, notifying us after each payment success or failure via a PayPal IPN message. Drupal does not trigger any payment via a monthly cron job or script.

If you are considering PayPal, you should work out whether you'll need to set up a PayPal Business account in order to accept payments for your business. These are sometimes referred to as Merchant Accounts. You will also need to make sure that you have everything in place to clear funds from your PayPal account into your bank account, and to adhere to all taxation requirements. Talk to your accountant or finance team and make sure you test things thoroughly (see 'Testing' section below). The rules for this will vary from country to country and are beyond the scope of this article.

PayPal's Instant Payment Notification (IPN) system is an excellent feature. We like it because:

  • IPNs facilitate 'reporting home' to our Drupal application about scheduled payments
  • IPN notification web service receipt was already implemented in the Drupal Commerce module. This made it easy to implement application-specific hooks based on events, e.g. restricting access to premium when a failed payment IPN was received
  • IPN notifications include all of the required success and failure payment events
  • IPN notifications have a robust retry architecture, so if our application is offline or unavailable for any period of time, notifications from PayPal don't get lost or discarded
  • PayPal's web interface allows us to easily investigate payment events. If we need to investigate a payment event, we have all the information at our fingertips.

Drupal – Commerce PayPal

The great thing about Drupal is the number of contrib modules already published for our use. This means we can concentrate our efforts on building the innovative and bespoke functionality our project needs, and not reinvent the integration wheel. The Drupal Commerce module already has integration with PayPal for payment processing, and already includes an IPN listener to catch asynchronous payment messages.

QA and Testing – This Time For Cash

We all know the value of incorporating proper Quality Assurance (QA) and testing into the build cycle of any enterprise application. This is the best way to reduce painful cleanup and issue resolution of functional bugs making their way to production.

But where automated payments are involved, the potential risks and implications around implementation bugs are considerably further reaching.

As well as all the standard functional testing and unit testing, Catalyst have some additional best practices that we have included when we are working with Payment System integrations:

  • Be aware that test payment gateways provided by providers (including PayPal) are not enough to test the end-to-end behaviour of all functionality. Of course developers and QA should make use of them, but part of the application testing needs to involve real payments in sandboxed environments. This is a little non-intuitive
  • We advise getting some pre-paid credit or debit cards for testing purposes. These can be used to trigger real transactions as part of the QA phase to trigger expected events such as insufficient funds and cancellation of transaction after the event (via phone call)
  • Involve the whole dev and infrastructure team in discussions to make sure that there is no chance that non-production environments can ever trigger real payments.


We hope you find this information useful. If you have further questions, please reach out.

NOTE: Please do not consider this article as an endorsement for PayPal above all other payment gateways. Catalyst has no commercial commitment to PayPal other than as a standard customer. There are a number of considerations around the selection of credit card payment facilities that are outside the scope of this blog.

06 September 2016

Catalyst Blog


7 Themes of Catalyst

by Don Christie

OS//OS Talk – 7 Themes of Catalyst

I gave a talk at the second Open Source Open Society conference in Wellington recently. I was asked to talk about how Catalyst had grown and evolved over the last 20 years and was allocated seven minutes for my talk. For a 20 year old company that's quite a lot to cover in a short time, especially as it is my favourite topic.

So, I decided to do this by touching on seven themes that describe our company and give an essence of who we are and what drives us. This seemed to resonate with the audience and the general thrust of the conference, so I am grateful to have had the opportunity to present.

Here are my preparation notes:

1. Catalyst

Catalyst in 2016 is in its 20th year of operation. We are a company that makes free and open source software (free software from now) work beautifully for our clients. People are good enough to pay us for this work and to develop even more free software. Catalyst employees have contributed to over 170 projects, often as a result of work carried out for our clients, with their permission.

With 250 staff and with offices in Wellington, Christchurch, Auckland, Sydney, Melbourne and Brighton (UK) we are the largest free software company in Australasia.

Recently we have built a public cloud in New Zealand, entirely based on free software and set up to compete with the likes of AWS and Azure. We will be opening our third region late in 2016. This is an achievement we are all very proud of and builds on capabilities across the company.

2. Purpose before profit

All organisations need a purpose. There really isn't much point in existing just to print money. We have a central bank to do that. It's a clear common purpose that gets us out of bed in the morning.

The free software ethos and mindset is in our bones. Our company promotes the free software mindset and way of operating in the widest possible sense.

We believe these collective values drive how we use technology and can lead to a reduction in imbalances in society.

Profit is important. Not least, because it demonstrates that our approach is a legitimate way of doing business and not a fringe activity.

3. The power of technology is asymmetric, free software can fix this

We talk a lot about the growing divide between rich and poor. But what we don't talk enough about is the gaping chasm in power between suppliers of technology platforms and consumers. In the 21st century it is impossible to participate in our communities without using technology. However, many providers of technology force us to participate in a way that most people would rather not.

They control our private information, they dictate what we are allowed to see and do and force us to adopt patterns of behaviour the aggregate flows of revenue to fewer and fewer corporations.

Not just that, but the pace of change is so fast that the technically less literate, often older people, are not able to keep up and therefore they are more and more excluded from the world that many of us take for granted.

Governments have near unfettered access to our personal lives in a way that totalitarian regimes of the past could only dream of.

Free software (especially strong copyleft licensing regimes) attempts to address this balance by placing the right to control technology and how it is used firmly back in the hands of users. The role for technologists in this regime is to help and serve our communities so that they are able to benefit from this right.

4. Sharing is a good thing

It's just like your mother used to say, sharing is good. Around the time we leave primary school we start getting brainwashed into believing the opposite. Sharing becomes “cheating” and later, stealing, a heinous criminal activity.

Software “End user licence agreements” - EULAs can literally take days to read but mostly they cover the different ways sharing is wrong and punishable.

But our society doesn't function like that. We need to share. Not only because we all “stand on the shoulders of giants” but because every day we require support and knowledge from those around us and more broadly, around the world.

Free software, creative commons and open data all recognise the importance of being able to share.

5. Permissionless innovation

Catalyst has coined the by-line “freedom to innovate” to express this concept.

Free software has created this extraordinary opportunity for innovation to take place, building on the works of others without requiring anyone's permission to do so.

To use and further develop free software you don't need:

  • Contracts
  • Lawyers
  • Heads of agreement
  • Memorandums of understanding.

Koha, the GPL licensed library management system was developed in 1999 for Horowhenua Library Trust in Levin, New Zealand. The code was released for anyone to use. The Koha development team received their first patch from a large car manufacturer in Detroit who had decided to use the software to catalogue their thousands of manuals. The took the code from the Internet repository, changed it, ran it and contributed some changes back to the core product. All without third party involvement. Now, of course, Koha is used in thousands of libraries across the globe, translated into dozens of languages and is the most feature rich Library Management System in the world. The great part, it is still free.

6. Don't be passive

Positive change is not something that happens by accident. We have to make choices and sometimes those choices are not convenient. They require us to learn or to go an extra step. But, in Catalyst's experience,making harder choices always pays off.

Adopt these changes for yourself:

Switch to Firefox as your default browser on all devices. Firefox is the only mainstream free and open source browser. It keeps the others honest. It's very good.

If you are a developer, develop for Firefox first. Your websites will be more standards compliant and more likely to work across all other browsers. If you use IE or Chrome first you are likely to run into compatibility problems.

Try Ubuntu or Linux Mint on your desktop. These are beautiful fully featured and far less confusing to users as the proprietary equivalents.

Use LibreOffice rather than MicrosoftOffice. It uses open document formats by defaults as a bonus.

If you are releasing free and open source software, chose a licence that respects and perpetuates the rights of users. The copyleft, GPL, licence family is a great start.

If you are not prepared to do any of the above...consider this, why are you here?

7. Freedom always wins in the end

It is a condition of human kind. History tells us that no matter how dark the days become we humans are always struggling for freedom.

In my shortish lifetime alone I have seen the rolling back of Communist inspired totalitarianism in Eastern Europe, the end of Apartheid in South Africa and the legalisation and legitimisation of homosexual relationships. Despite occasional setbacks, democracy is the default state for most of the world's countries. This is an issue that transcends normal party politics. As far as I can tell, all political parties have their authoritarian tendencies and most have more freedom loving wings. The latter groups need to be encouraged and supported.

Technology that has freedom baked in also wins. People forget that there were proprietary, non-free versions of the Internet – such as Compuserve. But the Internet, that was based on ideals and protocols and software that was open and free won, and keeps winning. Linux is now used on more devices than any other operating system. Free and open source software drives most new startups as well as the biggest technology companies in the world.

People like to be on the winning team and when history comes to judge you, be remembered for being on the side of freedom.

24 July 2016

Andrew Ruthven

Allow forwarding from VoiceMail to cellphones

Something I've been wanting to do with our Asterisk PBX at Catalyst for a while is to allow having callers that hit VoiceMail to be forwarded the callee's cellphone if allowed. As part of an Asterisk migration we're currently carrying out I finally decided to investigate what is involved. One of the nice things about the VoiceMail application in Asterisk is that callers can hit 0 for the operator, or * for some other purpose. I decided to use * for this purpose.

I'm going to assume a working knowledge of Asterisk dial plans, and I'm not going to try and explain how it works. Sorry.

When a caller hits * the VoiceMail application exits and looks for a rule that matches a. Now, the simple approach looks like this within our macro for handling standard extensions:

exten => a,1,Goto(pstn,027xxx,1)

(Where I have a context called pstn for placing calls out to the PSTN).

This'll work, but anyone who hits * will be forwarded to my cellphone. Not what I want. Instead we need to get the dialled extension into a place where we can perform extension matching on it. So instead we'll have this (the extension is passed into macro-stdexten as the first variable - ARG1):

exten => a,1,Goto(vmfwd,${ARG1},1)

Then we can create a new context called vmfwd with extension matching (my extension is 7231):

exten => 7231,1,Goto(pstn,027xxx,1)

I actually have a bit more in there to do some logging and set the caller ID to something our SIP provider will accept, but you get the gist of it. All I need to do is to arrange for a rule per extension that is allowed to have their VoiceMail callers be forwarded to voicemail. Fortunately I have that part automated.

The only catch is for extensions that aren't allowed to be forwarded to a cellphone. If someone calling their VoiceMail hits * their call will be hung up and I get nasty log messages about no rule for them. How do we handle them? Well, we send them back to VoiceMail. In the vmfwd context we add a rule like this:

exten => _XXXX,1,VoiceMail(${EXTEN}@sip,${voicemail_option})
  same => n,Hangup

So any extension that isn't otherwise matched hits this rule. We use ${voicemail_option} so that we can use the same mode as was used previously.

Easy! Naturally this approach won't work for other people trying to do this, but given I couldn't find write ups on how to do this, I thought it be might be useful to others.

Here's my macro-stdexten and vmfwd in full:

exten => s,1,Progress()
exten => s,n,Dial(${ARG2},20)
exten => s,n,Goto(s-${DIALSTATUS},1)
exten => s-NOANSWER,1,Answer
exten => s-NOANSWER,n,Wait(1)
exten => s-NOANSWER,n,Set(voicemail_option=u)
exten => s-NOANSWER,n,Voicemail(${ARG1}@sip,u)
exten => s-NOANSWER,n,Hangup
exten => s-BUSY,1,Answer
exten => s-BUSY,n,Wait(1)
exten => s-BUSY,n,Set(voicemail_option=b)
exten => s-BUSY,n,Voicemail(${ARG1}@sip,b)
exten => s-BUSY,n,Hangup
exten => _s-.,1,Goto(s-NOANSWER,1)
exten => a,1,Goto(vmfwd,${ARG1},1)
exten => o,1,Macro(operator)


exten => _XXXX,1,VoiceMail(${EXTEN}@sip,${voicemail_option})
  same => n,Hangup

#include extensions-vmfwd-auto.conf

And I then build extensions-vmfwd-auto.conf from a script that is used to generate configuration files for defining accounts, other dial plan rule entries and phone provisioning files.

With thanks to John Kiniston for the suggestion about the wildcard entry in vmfwd.

16 July 2016

Jonathan Harker

British Museum

After a quick squizz in the Liberty and Schott Music shops, we ended up spending the rest of the day in the British Museum. The Rosetta Stone is the first thing you are presented with in the Egypt halls, yet we didn’t see it because it was surrounded by people which we mistook for simply a group of tourists. We wandered around admiring huge granite Babylonian lions, Assyrian friezes, marble chunks of the Parthenon and the Mausoleum of Halicarnassus, vaguely wondering where it was. Luckily there was a guided tour at 5pm that led us right to it. There was also red figure Greek pottery, bits of a marae, bronze age jewellery, coins from the Thames, cuneiform tablets, mediæval clocks and mechanisms, and Roman mosaics. So much history!

14 July 2016

Jonathan Harker

Salisbury Cathedral

Today we went to Andover to visit a special music shop, and then on to Salisbury Cathedral, via a quick rubber-neck at Stonehenge off the A303. We arrived in time for Evensong to hear the Leighton Magdalen service. The cathedral is huge, nearly 800 years old and beautiful, and the history of its construction inspired Follett’s novel, Pillars of the Earth. The Magna Carta document (or at least, one of the surviving four) hangs out the back on display in the 13th century chapter house, behind the cloister.

Salisbury Cathedral. Salisbury Cathedral cloister and cedars Rebekah was here!

Then we went to a nearby pub, called The Chapter House, for tea, then back to London.

02 December 2014

Andrew Ruthven

LCA2015 - Debian Miniconf & nz2015 Debian mini-DebConf

nz2015 mini-DebConf

Already attending Come a couple of days earlier and attend the mini-DebConf too! There will be a day of talks with a strong focus on the Debian project and a bug squashing day.

Debian Miniconf

After 5 years, the Debian Miniconf is back! Run as part of 2015, this event will attract speakers talking on topics that suit the broader audience attending LCA. The Debian Miniconf has been one of the largest miniconfs in the history of

For more information about both these events which I'm organising, head over to:!

25 August 2014

Dan Marsden

SCORM hot topics.

As a follow up from the GSOC post I thought it might be useful to mention a few things happening with SCORM at the moment.

There are currently approx 71 open issues related to SCORM in the Moodle tracker at the moment, of those 38 are classed as bugs/issues I should fix in stable branches at some point, 33 are issues that are really feature/improvement requests.

Issues about to be fixed and under development
MDL-46639 – External AICC packages not working correctly.
MDL-44548 – SCORM Repository auto-update not working.

Issues that are  high in my list of things to look at and I hope to look at sometime soon.
MDL-46961 – SCORM player not launching in Firefox when new window being used.
MDL-46782 – Re-entry of a scorm not using suspend_data or resuming itself should allow returning to the first sco that is not complete.
MDL-45949 – The TOC Tree isn’t quite working as it should after our conversion to YUI3 – it isn’t expanding/collapsing in a logical manner – could be a bit of work here to make this work in the right way.

Issues recently fixed in stable releases.
MDL-46940 – new window option not working when preview mode disabled.
MDL-46236 – Start new attempt option ignored if new window used.
MDL-45726 – incorrect handling of review mode.

New improvements you might not have noticed in 2.8 (not released yet)
MDL-35870 -Performance improvements to SCORM
MDL-37401 -SCORM auto-commit – allows Moodle to save data periodically even if the SCORM doesn’t call “commit”

New improvements you might not have noticed in 2.7:
MDL-28261 -Check for live internet connectivity while using SCORM – warns user if SCORM is unable to communicate with the LMS.
MDL-41476 – The SCORM spec defines a small amount of data that can be stored when using SCORM 1.2 packages, we have added a setting that allows you to disable this restriction within Moodle to allow larger amounts of data to be stored (you may need to modify your SCORM package to send more data to make this work.)

Thanks to Ian Wild, Martin Holden, Tony O’Neill, Peter Bowen, André Mendes, Matteo Scaramuccia, Ray Morris, Vignesh, Hansen Ler, Faisal Kaleem and many other people who have helped report/test and suggest fixes related to SCORM recently including the Moodle HQ Integration team (Eloy, Sam, Marina, Dan, Damyon, Rajesh) who have all been on the receiving end of reviewing some SCORM patches recently!

GSOC 2014 update

Another year of GSOC has just finished and Vignesh has done a great job helping us to improve a number of areas of SCORM!
I’m really glad to finally have some changes made to the JavaScript datamodel files as part of MDL-35870 – I’m hoping this will improve the performance of the SCORM player as the JavaScript can now be cached properly by the users browser rather than dynamically generating it using PHP.

Vignesh has made a number of general bug fixes to the SCORM code and has also tidied up the code in the 2.8 branch so that it now complies with Moodle’s coding guidelines.

These changes have involved almost every single file in the SCORM module and significant architectural changes have been made. We’ve done our best to avoid regresssions (thanks Ray for testing SCORM 2004) but due to the large number of changes (and the fact that we only have 1 behat test for SCORM) It would be really great if people could test the 2.8 branch with their SCORM content before release so we can pick up any other regressions that may have occurred.

Thanks heaps to Vignesh for his hard work on SCORM during GSOC – and kudos to Google for running a great program and providing the funding to help it happen!

10 July 2014

Andrew Ruthven

Cloud - in New Zealand!

I've spent a reasonable chunk of the past year working on a project we launched last month, Catalyst Cloud! It is using OpenStack with Ceph as the object store. It has taken a lot of work, and it is now very exciting seeing the level of interest there we're receiving about this new service!

The great part of this is that we can now offer private cloud services to our customers which provides all the flexibility that we've come to expect with the "cloud", but hosted in New Zealand by a New Zealand owned company so no concerns about jurisdiction of your data! Not only are we able to offer private cloud services on our OpenStack cluster(s), but we can also deploy OpenStack onto our customers own hardware using our ProdStack solution (I get to look directly at the Dashboard shown on that page, which is pretty cool).

Next up is deploying another OpenStack cluster in our new data centre (which is another project I'm working on). In the near future we also hope to start using Open Compute Project hardware for our clusters.

Dan Marsden

Goodbye Turnitin…

Time to say goodbye to the “Dan Marsden Turnitin plugin”… well almost!

Turnitin have done a pretty good job of developing a new plugin to replace the code that I have been working on since Moodle 1.5!

The new version of their plugin contains 3 components:

  1. A module (called turnitintool2) which contains the majority of the code for connecting to their new API and is a self-contained activity like their old “turnitintool” plugin
  2. A replacement plugin for mine (plagiarism_turnitin) which allows you to use plagiarism features within the existing Moodle Assignment, Workshop and forum modules.
  3. A new Moodle block that works with both the above plugins.

The Plugins database entry has been updated to replace my old code with the latest version from Turnitin, we have a number of clients at Catalyst using the new plugin and the migration has mostly gone ok so far – there are a few minor differences between my plugin and the new version from Turnitin so I encourage everyone to test the upgrade to the new version before running it on their production sites.

I’m encouraging most of our clients to update to the new plugin at the end of this year but I will continue to provide basic support for my version running on all Moodle versions up to Moodle 2.7 and my code continues to be available from my github repository here:

Thanks to everyone who has helped in the past with the plugin I wrote – hopefully this new version from Turnitin will meet everyone’s needs!

31 October 2012

Chris Cormack

Signoff statistics for October 2012

Here are the signoff statistics for bugs in October 2012
  • Kyle M Hall- 24
  • Owen Leonard- 18
  • Chris Cormack- 15
  • Nicole C. Engard- 10
  • Mirko Tietgen- 9
  • Marc Véron- 6
  • Frédéric Demians- 5
  • Jared Camins-Esakov- 5
  • Magnus Enger- 4
  • Jonathan Druart- 4
  • M. de Rooy- 3
  • Melia Meggs- 3
  • wajasu- 2
  • Paul Poulain- 2
  • Fridolyn SOMERS- 2
  • Tomás Cohen Arazi- 2
  • Matthias Meusburger- 1
  • Katrin Fischer- 1
  • Julian Maurice- 1
  • Koha Team Lyon 3- 1
  • Mason James- 1
  • Elliott Davis- 1
  • mathieu saby- 1
  • Robin Sheat- 1

16 October 2012

Chris Cormack

Unsung heroes of Koha 26 – The Ada Lovelace Day Edition

Darla Grediagin

Darla has been using Koha from 2006, for the Bering Strait School District in Alaska. This is pretty neat in itself, what is cooler is that as far as I know, they have never had a ‘Support Contract’. Doing things either by themselves or with the help of IT personnel as needed. One of Darla’s first blogposts that I read was about her struggles trying to install Debian on an Emac. I totally respect anyone who is trying to reclaim hardware from the darkside 🙂

Darla has presented on Koha at conferences, and maintains a blog that has useful information, including sections of what she would do differently. As well as some nice feel good bits like this, from April 2007

I know I had an entry titled this before, but I do love OSS programs.   Yesterday I mentioned that I would look at Pines because I like the tool it has to merge MARC records.  Today a Koha developer emailed me to let me know that he is working on this for Koha and it should be available soon.  I can’t imagine getting that kind of service from a vendor.

Hopefully she will be able to make it Kohacon13 in Reno, NV. It would be great to put a face to the email address 🙂

10 October 2012

Chris Cormack

New Release team for Koha 3.12

Last night on IRC the Koha Community elected a new release team, for the 3.12 release. Once again it is a nicely mixed team, there are 16 people involved, from  8 different countries (India, New Zealand, USA, Norway, Germany, France, Netherlands, Switzerland) and four of the 12 roles are filled by women.

The release team will be working super hard to bring you the best release of Koha yet, and you can help:

  • Reporting bugs
  • Testing bug fixes
  • Writing up enhancement requests
  • Using Koha
  • Sending cookies
  • Inventing time travel
  • Killing MARC
  • Winning the lottery and donating the proceeds to the trust to use for Koha work.

24 July 2012

Pass the Source

Google Recruiting

So, Google are recruiting again. From the open source community, obviously. It’s where to find all the good developers.

Here’s the suggestion I made on how they can really get in front of FOSS developers:

Hi [name]

Just a quick note to thank you for getting in touch of so many our
Catalyst IT staff, both here and in Australia, with job offers. It comes
across as a real compliment to our company that the folks that work here
are considered worthy of Google’s attention.

One thing about most of our staff is that they *love* open source. Can I
suggest, therefore, that one of the best ways for Google to demonstrate
its commitment to FOSS and FOSS developers this year would be to be a
sponsor of the NZ Open Source Awards. These have been very successful at
celebrating and recognising the achievements of FOSS developers,
projects and users. This year there is even an “Open Science” category.

Google has been a past sponsor of the event and it would be good to see
you commit to it again.

For more information see:

Many thanks

09 July 2012

Andrew Caudwell

Inventing On Principle Applied to Shader Editing

Recently I have been playing around with GLSL Sanbox (github), a what-you-see-is-what-you-get shader editor that runs in any WebGL capable browser (such as Firefox, Chrome and Safari). It gives you a transparent editor pane in the foreground and the resulting compiled fragment shader rendered behind it. Code is recompiled dynamically as the code changes. The latest version even has syntax and error highlighting, even bracket matching.

There have been a few other Webgl based shader editors like this in the past such as Shader Toy by Iñigo Quílez (aka IQ of Demo Scene group RGBA) and his more recent (though I believe unpublished) editor used in his fascinating live coding videos.

Finished compositions are published to a gallery with the source code attached, and can be ‘forked’ to create additional works. Generally the author will leave their twitter account name in the source code.

I have been trying to get to grips with some more advanced raycasting concepts, and being able to code something up in sandbox and see the effect of every change is immensely useful.

Below are a bunch of my GLSL sandbox creations (batman symbol added by @emackey):



GLSL Sandbox is just the latest example of the merit of software development tools that provide immediate feedback, and highlights the major advantages of scripting languages have over heavy compiled languages with long build and linking times that make experimentation costly and tedious. Inventing on Principle, a presentation by Bret Victor, is a great introduction to this topic.

I would really like a save draft button that saves shaders locally so I have some place to save things that are a work in progress, I might have to look at how I can add this.

Update: Fixed links to point at

05 June 2012

Pass the Source

Wellington City Council Verbal Submission

I made the following submission on the Council’s Draft Long Term Plan. Some of this related to FLOSS. This was a 3 minute slot with 2 minutes for questions from the councillors.


I have been a Wellington inhabitant for 22 years and am a business owner. We employ about 140 staff in Wellington, with offices in Christchurch, Sydney, Brisbane and the UK. I am also co-chair of NZRise which represents NZ owned IT businesses.

I have 3 Points to make in 3 minutes.

1. The Long Term plan lacks vision and is a plan for stagnation and erosion

It focuses on selling assets, such as community halls and council operations and postponing investments. On reducing public services such as libraries and museums and increasing user costs. This will not create a city where “talent wants to live”. With this plan who would have thought the citizens of the city had elected a Green Mayor?

Money speaks louder than words. Both borrowing levels and proposed rate increases are minimal and show a lack of investment in the city, its inhabitants and our future.

My company is about to open an office in Auckland. A manager was recently surveying staff about team allocation and noted, as an aside, that between 10 and 20 Wellington staff would move to Auckland given the opportunity. We are not simply competing with Australia for hearts and minds, we are competing with Auckland whose plans for investment are much higher than our own.

2. Show faith in local companies

The best way to encourage economic growth is to show faith in the talent that actually lives here and pays your rates. This means making sure the council staff have a strong direction and mandate to procure locally. In particular the procurement process needs to be overhauled to make sure it does not exclude SME’s (our backbone) from bidding for work (see this NZCS story). It needs to be streamlined, transparent and efficient.

A way of achieving local company participation in this is through disaggregation – the breaking up large-scale initiatives into smaller, more manageable components. For the following reasons:

  • It improves project success rates, which helps the public sector be more effective.
  • It reduces project cost, which benefits the taxpayers.
  • It invites small business, which stimulates the economy.

3. Smart cities are open source cities

Use open source software as the default.

It has been clear for a long time that open source software is the most cost effective way to deliver IT services. It works for Amazon, Facebook, Red Hat and Google and just about every major Silicon Valley success since the advent of the internet. Open source drives the internet and these companies because it has an infinitely scalable licensing and model – free. Studies, such as the one I have here from the London School of Economics, show the cost effectiveness and innovation that comes with open source.

It pains me to hear about proposals to save money by reducing libraries hours and increasing fees, when the amount of money being saved is less than the annual software licence fees our libraries pay, when world beating free alternatives exist.

This has to change, looking round the globe it is the visionary and successful local councils that are mandating the use of FLOSS, from Munich to Vancouver to Raleigh NC to Paris to San Francisco.

As well as saving money, open source brings a state of mind. That is:

  • Willingness to share and collaborate
  • Willingness to receive information
  • The right attitude to be innovative, creative, and try new things

Thank you. There should now be 2 minutes left for questions.

05 January 2012

Pass the Source

The Real Tablet Wars

tl;dr formally known as Executive Summary, Openness + Good Taste Wins

Gosh, it’s been a while. But this site is not dead. Just been distracted by and twitter.

I was going to write about Apple, again. A result of unexpected and unwelcome exposure to an iPad over the Christmas Holidays. But then I read Jethro Carr’s excellent post where he describes trying to build the Android OS from Google’s open source code base. He quite mercilessly exposes the lack of “open” in some key areas of that platform.

It is more useful to look at the topic as an issue of “open” vs “closed” where iPad is one example of the latter. But, increasingly, Android platforms are beginning to display similar inane closed attributes – to the disadvantage of users.

Part of my summer break was spent helping out at the premier junior sailing regatta in the world, this year held in Napier, NZ. Catalyst, as a sponsor, has built and is hosting the official website.

I had expected to swan around, sunbathing, drinking cocktails and soaking up some atmosphere. Instead a last minute request for a new “live” blogging section had me blundering around Joomla and all sorts of other technology with which I am happily unfamiliar. Days and nightmares of iPads, Windows, wireless hotspots and offshore GSM coverage.

The plan was simple, the specialist blogger, himself a world renown sailor, would take his tablet device out on the water on the spectator boat. From there he would watch and blog starts, racing, finishes and anguished reactions from parents (if there is one thing that unites races and nationalities, it is parental anguish over sporting achievement).

We had a problem in that the web browser on the tablet didn’t work with the web based text editor used in the Joomla CMS. That had me scurrying around for a replacement to the tinyMCE plugin, just the most common browser based editing tool. But a quick scan around various forums showed me that the alternative editors were not a solution and that the real issue was a bug with the client browser.

“No problem”, I thought. “Let’s install Firefox, I know that works”.

But no, Firefox is not available to iPad users  and Apple likes to “protect” its users by only tightly controlling whose applications are allowed to run on the tablet. Ok, what about Chrome? Same deal. You *have* to use Apple’s own buggy browser, it’s for your own good.

Someone suggested that the iPad’s operating system we were using needed upgrading and the new version might have a fixed browser. No, we couldn’t do that because we didn’t have Apple’s music playing software, iTunes, on a PC. Fortunately Vodafone were also a sponsor and not only did they download an upgrade they had iTunes handy. Only problem, the upgrade wiped all the apps that our blogger and his family had previously bought and installed.

Er, and the upgrade failed to fix the problem. One day gone.

So a laptop was press ganged into action, which, in the end was a blessing because other trials later showed that typing blogs fast, on an ocean swell, is very hard without a real keyboard. All those people pushing tablets at schools, keep in mind it is good to have our children *write* stuff, often.

The point of this post is not really to bag Apple, but to bag the mentality that stops people using their own devices in ways that help them through the day. I only wanted to try a different browser to Safari, not an unusual thing to do. Someone else might want to try out a useful little application a friend has written for them, but that wouldn’t be allowed.

But the worst aspect of this is that because of Apple’s success in creating well designed gadgets other companies have decided that “closed” is also the correct approach to take with their products. This is crazy. It was an open platform, Linux Kernel with Android, that allowed them to compete with Apple in the first place and there is no doubt that when given a choice, choice is what people want – assuming “taste” requirements are met.

Other things being equal*, who is going to chose a platform where the company that sold you a neat little gadget controls all the things you do on it? But there is a strong trend by manufacturers such as Samsung, and even Linux distributions, such asUbuntu, to start placing restrictions on their clients and users. To decide for all of us how we should behave and operate *our* equipment.

The explosive success of the personal computer was that it was *personal*. It was your own productivity, life enhancing device. And the explosive success of DOS and Windows was that, with some notable exceptions, Microsoft didn’t try and stop users installing third party applications. The dance monkey boy video is funny, but the truth is that Microsoft did want “developers, developers, developers, developers” using its platforms because, at the time, it knew it didn’t know everything.

Apple, Android handset manufacturers and even Canonical (Ubuntu) are falling into the trap of not knowing that there is stuff they don’t know and they will probably never know. Similar charges are now being made about Facebook and Twitter. The really useful devices and software will be coming from companies and individuals who realise that whilst most of what we all do is the same as what everyone else does, it is the stuff that we do differently that makes us unique and that we need to control and manage for ourselves. Allow us do that, with taste, and you’ll be a winner.

PS I should also say “thanks” fellow sponsors Chris Devine and Devine Computing for just making stuff work.

* I know all is not equal. Apple’s competitive advantage it “has taste” but not in its restrictions.

18 May 2011

Andrew Caudwell

Show Your True Colours

This last week saw the release of fairly significant update to Gource – replacing the out dated, 3DFX-era rendering code, with something a bit more modern, utilizing more recent OpenGL features like GLSL pixel shaders and VBOs.

A lot of the improvements are under the hood, but the first thing you’ll probably notice is the elimination of banding artifacts in Bloom, the illuminated fog Gource places around directories. This effect is pretty tough on the ‘colour space’ of so called Truecolor, the maximum colour depth on consumer monitors and display devices, which provides 256 different shades of grey to play with.

When you render a gradient across the screen, there are 3 or 4 times more pixels than there are shades of each colour, producing visible ‘bands’ of the same shade. If multiple gradients like this get blended together, as happens with bloom, you simply run out of ‘in between’ colours and the issue becomes more exaggerated, as seen below (contrast adjusted for emphasis):


Those aren’t compression artifacts you’re seeing!

Gource now uses colour diffusion to combat this problem. Instead of sampling the exact gradient of bloom for the distance of a pixel from the centre of a directory, we take a fuzzy sample in that vicinity instead. When zoomed in, you can see the picture is now slightly noisy, but the banding is completely eliminated. Viewed at the intended resolution, you can’t really see the trickery going on – in fact the effect even seems somewhat more natural, a bit closer to how light bouncing off particles of mist would actually behave.


The other improvement is speed – everything is now drawn with VBOs, large batches of objects geometry passed to the GPU in as few shipments as possible, eliminating CPU and IO bottle necks. Shadows cast by files and users are now done in a second pass on GPU using the same geometry as used for the lit pass – making them really cheap compared to before when we effectively wore the cost of having to draw the whole scene twice.

Text is now drawn in single pass, including shadows, using some fragment shader magic (take two samples of the font texture, offset by 1-by-1 pixels, blend appropriately). Given the ridiculous amount of file, user and directory names Gource draws at once with some projects (Linux Kernel Git import commit, I’m looking at you), doing half as much work there makes a big difference.

06 October 2010

Andrew Caudwell

New Zealand Open Source Awards

I discovered today that Gource is a finalist in the Contributor category for the NZOSA awards. Exciting stuff! A full list of nominations is here.

I’m currently taking a working holiday to make some progress on a short film presentation of Gource for the Onward!.

Update: here’s the video presented at Onward!:

Craig Anslow presented the video on my behalf (thanks again Craig!), and we did a short Q/A over Skype afterwards. The music in the video is Aksjomat przemijania (Axiom of going by) by Dieter Werner. I suggest checking out his other work!

14 August 2009

Piers Harding

Auth SAML 2.0 for Mahara

Following on from the SAML 2.0 work that I've done recently for Moodle, I thought it was useful to do the same for the Mahara ePortfolio service, while I was in the same space. Details of the first release can be found here, with tested version for both trunk, and 1.1_STABLE.

02 August 2009

Piers Harding

Moodle and SAML 2.0 Web SSO

Of late I have been doing a lot of SSO integration work for the NZ Ministry of Education, and during this time I came across an excellent project FEIDE. One of the off shoots of this has been the development of a high quality PHP library for SAML 2.0 Web SSO - SimpleSAMLPHP.

For Moodle integration, Erlend Strømsvik of Ny Media AS, developed an authentication plugin, which I've made a number of changes to around configuration options, and Moodle session integration. This has now been documented and added to Moodle Contrib to give it better visibility to the Moodle community at large. Documentation is here and the contrib entry is here.

27 June 2009

Piers Harding

Perl sapnwrfc 0.30

I doing some work for a client recently, I got the opportunity to do some major performance work on sapnwrfc for Perl. The net result is that a number of memory leaks, mainly of Perl values not going out of scope properly, have been fixed.

Additionally, I've had some time to put together a proper cookbook style set of examples in the sapnwrfc-cookbook. These examples, while specifically for Perl, are almost identical for sapnwrfc for Python, Ruby, and PHP too.