Scheduling for the internet

While trying to figure out the best way to synchronise scheduled event start times across different users in different time zones, I managed to work my way around in a bit of a circle yesterday.

I have an app that allows users to schedule events and obviously specify start times. In my initial hacking I was specifying those start times and storing them in the database as strings (not even validated as dates, really just a place holder to mock up the site). So yesterday I thought I would tackle this to make it more functional.

I added a date picker widget and a time picker widget and fixed things so that only dates and times could be specified which I then stored in my database.

But wait, I thought, how do i know what timezone the user intends. After all, when i publish this event to other users I will want to give the start time in their timezone. Hmm... So I started my research on timezones.

I started out trying to put a timezone picker on my event scheduler page which would default to the current timezone of the clients browser. This actually isn't so simple.

A major complication is that I don't really want the timezone, I actually want the locale of which the timezone is only a feature. The other feature is daylight savings time (DST). There are only so many time zones (which is quite manageable) but there are lots of variations in the treatment of DST (not so manageable). Unfortunately for me I need to consider DST if I am to know what real time an event organiser is actually aiming for (they will always be working in local time I presume and would not care to specify start times in UTC).

Here are a few of the interesting libraries that I looked at to get get a handle on this.

• On the client to detect and select a timezone
• Josh Fraser provided the best hope for something simple with his client timezone and DST detection algorithm in Javascript. But he does mention that instead folks should use...
• Jon Nylander's jsTimezoneDetect solution. This is apparently much more advanced and works off the complete list of time locales from the Olson zoneinfo database. Unfortunately this would be tricky to integrate in my web page and would provide a huge number of options for users. I've seen these before on the internet and they are annoying.
• Then on the server to get a nice unix time in my database
• node-time looked interesting
• moment.js seemed to talk the talk but on further analysis I wasn't sure if it knew about DST or if I would have to tell it
• timezone-js may have been the most promising

But then came my small eureka moment... Why am I doing all this work? Well, pretty much because my client side controls give me strings and not date objects. However the browser does know what time locale it's in and how to present dates. So this is where I returned almost to my starting point.

I ripped out all the timezone selector stuff from my page and instead I used the client side date functions to generate a Date object there and transmit a nice simple unix time back to the server for storage. For those that don't know, unix times are the number of milliseconds since 00:00:00.000 01/01/1970 (UTC). They don't care about time locales. So now I do all the locale specific formatting and parsing in the browser. Seemed obvious after I'd done it :)

I may add a widget to my pages to let the user know which zone the times are being displayed in but I'm not sure even that is worth the effort. It would only catch a few issues with people working on devices with the wrong timezone set.

Grunt watch and the Node.js require cache revisited

Still inspired by James Shore's series "Let's Code: Test-Driven Javascript",  I've been continuing with my endeavors to get the Grunt watch stuff working flawlessly(?).

In my last post I mentioned some niggles that were remaining from my previous workaround.

• The workaround only addresses the Mongoose issue
• The workaround assumes intimate knowledge of Mongoose
• Grunt watch still explodes silently when unhandled errors are encountered in tests
• undefined references
• nonexistent requires
• etc.

The good news is that I think I have addressed all of these. In addition to that I've figured out some stuff about how to extend grunt and how to manipulate the Node.js require cache.

First off I thought I'd take a look at Mocha to see if it handled things better. After all Mocha also has a watch function.

• Mocha watch does not explode on undefined references (which is nice)
• Mocha watch does still explode on nonexistent requires (actually I didn't find this out till much later on when integrating with grunt)
• Mocha watch still failed to handle my Mongoose issue
• Unfortunately Mocha watch doesn't integrate with JSHint and actually I'd quite like to lint my code on file changes too

So despite only having a small advantage in not falling over so much I thought Mocha showed more promise than NodeUnit and as James noted it is much more active on GitHub. In fact it's under the same banner as Express and Jade which are definitely very popular and well maintained frameworks for Node.js.

Next thing was to integrate Mocha with Grunt so that i can use the Grunt watch function to both lint and run tests on file changes.

The nice thing about writing my own task to run Mocha instead of NodeUnit is that it was then quite easy to fix the issue of exploding on nonexistent requires... It just needed a try/catch around the mocha.run call. In retrospect I could probably have added this to the existing NodeUnit task but by the time I got to this point, I'd already ported all my tests to Mocha.

[A short interlude on Mocha and Should...]

James noted in his videos that Mocha is targeted as a BDD test framework and as such he is not so keen on it's verbosity. I can see what he means but, to be honest, I don't find it much of an issue and in fact quite like it, so for a while at least, I think i'll stick with it.

I also tried the should.js assert library that provides an interesting take on asserts by making them a bit more natural language like. Things like: thing.should.have.property(things).with.length(5);

On first take I thought cool and went full steam ahead in making all my asserts like this. Currently though I'm not sure I like it.

For one, I keep thinking that I should be able to write something in a natural way but find that it's not really supported - it kinda feels like I'm being teased. This will lessen I guess as I really learn the idioms.

A more annoying problem though is related to the way Javascript handles types and comparisons. I keep finding comparisons that i think should work and don't and then comparisons that I think shouldn't work and do! I think this is made worse by hiding the comparisons inside assert functions. As a result I'm starting to come to the opinion that not only is the should framework more trouble than it's worth but in fact any assert framework that hides comparison logic is not such a good idea to use in tests in Javascript. This includes very standard things like: assert.equal(object1, object2);

I may revert to just a single check function that will better reflect how comparisons would actually be written in production code. Ie: assert(conditionalCodeThatResolvesToTrueOrFalse);

[...interlude over]

So there I have it, I can now run my tests as files change and rely on the watch task to keep going no matter what happens (so far!). Just the mongoose problems to resolve then, and actually I added another.

• If a unit test beforeEach function falls over then the after functions are not run
• This means that as I open a database connection in before and close it in after, when I get such an error I then continue to get failures when files change due to not being able to open the database anymore (it's already open)
• Not as serious as the silent failures as at least the watch process keeps pinging me and I can restart it. But still a little annoying

This new issue got me thinking again about the require cache. My previous investigations here had proven fruitless but then, perhaps I had been led astray by some dubious comments on StackOverflow. Beware, this code does not work:

for (var key in Object.keys(require.cache)) {delete require.cache[key];}

So now I was thinking about the Mongoose module.

• The problem isn't that the changed module is still in cache
• The problem is that the Mongoose module is still in cache
• In fact the problem is that any modules are still in cache
• I must clear the cache completely before running my tests!
• Actually I had tried this and it didn't seem to work
• However I had tried it in my tests themselves, now I could try it in my new grunt task :)
• I had already needed to add code that dropped all my own files from cache to make things work. It made sense to drop the rest too when I come to think about it.

So i fixed the code above:

for (var key in require.cache) {delete require.cache[key];}

Tidied up my mocha task adding support for options and this is what I have in a new module...

To use this I dropped it in a grunt tasks directory and updated my grunt.js file...

Note that the call to loadTasks takes the directory name. Also note that I overrode the built in NodeUnit test task and that the options to pass into mocha are given in the mocha config property.

So that's it I no longer have to use my Mongoose workaround as the Mongoose module is cleaned up along with everything else before I run the tests :)

I hope this will save me from similar gotchas in other modules too, but I guess I'll just have to code and find out :D

Startup Weekend Amsterdam - The 5Live Crew

Had a fantastic time at Startup Weekend Amsterdam this weekend. Big up to the organisers :)

It was hard work and I think it will take a while for my girlfriend to forgive me (I found out about it and signed up Thursday with much too little discussion) but I'm so glad I did it.

It kicked of at 6pm Friday with 66 pitches! Some good, some bad, some completely indecipherable but all of them given and received in great spirit, in 60 seconds or under (with change overs I guess it would have been at least 2 hours of pitches, phew).

There was a shameless pitch to clone Kickstarter in Europe (did you know Europeans couldn't raise funds on Kickstarter?)... This actually got one of my votes.

There were a lot of pitches to provide match up services for sports enthusiasts, I counted at least 4. These were interesting to me as I know a French guy (hey, Alex, if you're reading!) who's had some success with this in Canada for ice hockey. Check out Hockey Community! Like I say interesting but i din't vote for any of them as I didn't want to encourage competition for my friend (who I think should branch out to other sports ;))

A cool sounding app called OhHeyWorld got my second vote. With one click it lets you notify friends and family when you arrive at a destination by checking in by email, facebook, twitter, etc all at once. I really liked this but it didn't get so many other votes so happily the guy pitching it ended up on our team :)

My final vote though went to a Googler who wanted to build an app on top of Google Hangouts to match coaches, music teachers, etc to people online for live lessons via video. 2 things peaked my interest. I've had this conversation before, particularly with musicians. And second it would be nice to learn something about integrating with Google Hangouts.

I didn't pitch any of my own ideas, although I kinda wish I had. Next time I will... and there will be a next time :)

So with all voting completed the pitches were narrowed down to 20. By which time the Google Hangout idea had merged with another to provide business mentoring over video conferencing, inspired by Quora (of which I'm largely unaware, but have just signed up). This is what I ended up working on with 7 other cool guys. We were 5 business guys, 2 developers and 1 designer (I think). Heavy on the business side and it showed after the first day. I'm not sure how many visions there were or how many times we pivoted (being 1 of the 2 techies I was pretty much head down coding the whole time - hoping that it was in the right direction) but at the end of the night on Saturday the cracks were starting to show. It was time for rest.

The next morning, although we were down one business guy who I think was unimpressed by the lack of focus and constant direction changing, there was definitely more commitment to get things done and to try and ship, after all we only had till 4pm.

We seemed to have a single vision now and we set about building it up and applying copy, etc. We needed a presentation and we needed some kind of validation. To be honest we already had some validation. All the pivoting the day before had come from surveying conference participants and collecting feedback. Ok, we didn't get out of the building physically but we did sell the expertise of one of our team members something like 7 times for $5 (Now he has to do some video conferences with the people who stumped up the cash). This wasn't even with conference folks, these were real people on the interwebs. We sold him through fiverr at an admittedly knock down price for his real estate know how and you may say that we only validated that people will buy gold if we sell for the price of coal. I disagree though, we validated that people are willing to pay for live interactive video sessions in which they can learn something... and they actually paid, not just promise to pay or expressed an interest.

This was our eventual proposition (I almost typed final but there may be more pivots to come) and 5Live was born. We will provide a market place to match up those with skills/knowledge to those who want to have those skills/knowledge. Sessions can be scheduled by the skilled for free and spots can be reserved by the young padowans for 5 euros/dollars or less. Then at the designated time each will click on some button and enter into a live interactive video conference through which knowledge will be imparted. The subsequent revenues will then be distributed back to the skilled.

I see it as a place where everyone is equal and sharing their wisdom with each other. Perhaps in the evening instead of watching TV. I see it as a natural progression from broadcast TV through social video like YouTube to the next wave of social knowledge sharing where you can ask your questions live. It's Etsy meets YouTube meets fiverr meets Quora (if I understand Quora correctly). This vision may not be the same as the other founders and may change once it's tested (will change!) but right now it looks like it has legs.

So at the end of the weekend what did we have?

Third place!! Yay :)

We were pushed out by a very worthy non-profit, charity/donation app called Easygiving who took first place for allowing people to easily manage and adjust monthly charity plans and donation distribution. And a service for helping you transfer your apps between mobile phone platforms when you switch to Android and can't find that app you loved so much on your iPhone (or vice versa) called Aloha. Kudos to them :)

But we still believe in our thing! And to prove it here are the slides, a video and a link so you can see more (if the link is dead then it probably means we changed the name and hit the big time - you should have been here last week ;))

• Slides
• 5Live site (minimum viable product?)