Simon Willison's Weblog: events

Storing times for human events

2024-11-27T20:45:25+00:00

I've worked on various event websites in the past, and one of the unintuitively difficult problems that inevitably comes up is the best way to store the time that an event is happening. Based on that past experience, here's my current recommendation.

This is the expanded version of a comment I posted on lobste.rs a few days ago, which ended up attracting a bunch of attention on Twitter.

The problem

An event happens on a date, at a time. The precise details of that time are very important: if you tell people to show up to your event at 7pm and it turns out they should have arrived at 6pm they'll miss an hour of the event!

Some of the worst bugs an events website can have are the ones that result in human beings traveling to a place at a time and finding that the event they came for is not happening at the time they expected.

So how do you store the time of an event?

The "best practice" that isn't

Any time you talk to database engineers about dates and times you're likely to get the same advice: store everything in UTC. Dates and times are complicated enough that the only unambiguous way to store them is in UTC - no daylight savings or timezones to worry about, it records the exact moment since the dawn of the universe at which the event will take place.

Then, when you display those times to users, you can convert them to that user's current timezone - neatly available these days using the Intl.DateTimeFormat().resolvedOptions().timeZone browser API.

There's a variant of this advice which you're more likely to hear from the PostgreSQL faithful: use TIMESTAMP WITH TIME ZONE or its convenient alias timestamptz. This stores the exact value in UTC and sounds like it might store the timezone too... but it doesn't! All that's stored is that UTC value, converted from whatever timezone was active or specified when the value was inserted.

In either case, we are losing critical information about when that event is going to happen.

Things that can go wrong

What's wrong with calculating the exact UTC time the event is starting and storing only that?

The problem is that we are losing crucial details about the event creator's original intent.

If I arrange an evening meetup for next year on December 3rd at 6pm, I mean 6pm local time, by whatever definition of local time is active on that particular date.

There are a number of ways this time can end up misinterpreted:

User error: the user created the event with an incorrect timezone
User error: the user created the event in the wrong location, and later needs to fix it
International timezone shenanigans: the location in which the event is happening changes its timezone rules at some point between the event being created and the event taking place

User error

By far the most common issue here is user error with respect to how the event was initially created.

Maybe you asked the user to select the timezone as part of the event creation process. This is not a particularly great question: most users don't particularly care about timezones, or may not understand and respect them to the same extent as professional software developers.

If they pick the wrong timezone we risk showing the wrong time to anyone else who views their event later on.

My bigger concern is around location. Imagine a user creates their event in Springfield, Massachusetts... and then a few days later comes back and corrects the location to Springfield, Illinois.

That means the event is happening in a different timezone. If the user fails to update the time of the event to match the new location, we're going to end up with an incorrect time stored in our database.

International timezone shenanigans

One of my favourite niche corners of the internet is the tz@iana.org mailing list. This is where the maintainers of the incredible open source tz database hang out and keep track of global changes to timezone rules.

It's easy to underestimate how much work this is, and how weird these rule changes can be. Here's a recent email proposing a brand new timezone: Antarctica/Concordia:

Goodmorning. I'm writing here to propose a new time zone for an all-year open Antarctic base. The base is a French–Italian research facility that was built 3,233 m (10,607 ft) above sea level at a location called Dome C on the Antarctic Plateau, Antarctica. https://en.wikipedia.org/wiki/Concordia_Station

The timezone is UTC+8 without DST.

That's a pretty easy one. Here's a much more complicated example from March 2023: Lebanon DST change internally disputed:

Lebanon is going through many internal disputes surrounding the latest decision to delay DST. Many institutions are refusing to comply with the change and are going to adopt regular DST on Sunday Mar 26th. Those institutions include but are not limited to:

News agencies

Religious organizations

Schools, universities, etc...

The refusal is mainly centered the legality of that decision and, obviously, the technical chaos it will create because of its short notice. Moreover, as some of the below articles mention, this is also causing sectarian strife.

Lebanon ended up with more than one timezone active at the same time, depending on which institution you were talking to!

It's surprisingly common for countries to make decisions about DST with very little notice. Turkey and Russia and Chile and Morocco are four more examples of countries that can often cause short-term chaos for software developers in this way.

If you've stored your event start times using UTC this is a big problem: the new DST rules mean that an already-existing event that starts at 6pm may now start at 5pm or 7pm local time, according to the UTC time you've stored in your database.

Microsoft Exchange and the DST update of 2007

Via fanf on Lobsters I heard about a fascinating example of this problem in action. In 2005 the Bush administration passed the Energy Policy Act of 2005, one part of which updated the rules for when DST would start across most of the USA.

This resulted in a bug where Microsoft Exchange and Outlook would display appointment times incorrectly! From Exchange Server and Daylight Saving Time (DST) 2007:

After installing the DST updates, all old recurring and single instance appointments that occur during the delta period between the DST 2007 rules and the previous DST rules will be one hour later. These appointments will need to be updated so that they will display correctly in Outlook and Outlook Web Access, and for CDO based applications.

Microsoft released a special "Exchange Calendar Update Tool" executable for people to run to fix all of those upcoming calendar events.

My recommendation: store the user's intent time and the location/timezone

My strong recommendation here is that the most important thing to record is the original user's intent. If they said the event is happening at 6pm, store that! Make sure that when they go to edit their event later they see the same editable time that they entered when they first created it.

In addition to that, try to get the most accurate possible indication of the timezone in which that event is occurring.

For most events I would argue that the best version of this is the exact location of the venue itself.

Users may find timezones confusing, but they hopefully understand the importance of helping their attendees know where exactly the event is taking place.

If you have the venue location you can almost certainly derive the timezone from it. I say almost because, as with anything involving time, there are going to be edge-cases - most critically for venues that are exactly on the line that divides one timezone from another.

I haven't sat down to design my ideal UI for this, but I can imagine something which makes it abundantly clear to the user exactly where and when the event is taking place at that crucial local scale.

Now that we've precisely captured the user's intent and the event location (and through it the exact timezone) we can denormalize: figure out the UTC time of that event and store that as well.

This UTC version can be used for all sorts of purposes: sorting events by time, figuring out what's happening now/next, displaying the event to other users with its time converted to their local timezone.

But when the user goes to edit their event, we can show them exactly what they told us originally. When the user edits the location of their event we can maintain that original time, potentially confirming with the user if they want to modify that time based on the new location.

And if some legislature somewhere on earth makes a surprising change to their DST rules, we can identify all of the events that are affected by that change and update that denormalized UTC time accordingly.

Timezone UIs suck, generally

As an aside, here's my least favorite time-related UI on the modern internet, from Google Calendar:

There isn't even a search option! Good luck finding America/New_York in there, assuming you knew that's what you were looking for in the first place.

Tags: databases, events, time, timezones

Quoting Jeremy Keith

2024-09-17T18:15:52+00:00

Something that I confirmed that other conference organisers are also experiencing is last-minute ticket sales. This is something that happened with UX London this year. For most of the year, ticket sales were trickling along. Then in the last few weeks before the event we sold more tickets than we had sold in the six months previously. […]

When I was in Ireland I had a chat with a friend of mine who works at the Everyman Theatre in Cork. They’re experiencing something similar. So maybe it’s not related to the tech industry specifically.

— Jeremy Keith

Tags: conferences, events, jeremy-keith

NumFOCUS DISCOVER Cookbook: Minimal Measures

2024-05-19T18:24:21+00:00

NumFOCUS DISCOVER Cookbook: Minimal Measures

NumFOCUS publish a guide "for organizers of conferences and events to support and encourage diversity and inclusion at those events."

It includes this useful collection of the easiest and most impactful measures that events can put in place, covering topics such as accessibility, speaker selection, catering and provision of gender-neutral restrooms.

Tags: events, diversity

What are good event venues to have a 100 person weekend hackathon in San Francisco?

2014-02-24T18:54:00+00:00

My answer to What are good event venues to have a 100 person weekend hackathon in San Francisco? on Quora

As a general rule, tech companies in San Francisco are very supportive of hackathons and keen to host events. Eventbrite have hosted this kind of event in their office in the past, and I'm certain there are a bunch of other companies with decent spaces that would be worth approaching. Does the hackathon have a specific topic? I suggest approaching companies related to that topic as a starting point.

Tags: events, san-francisco, quora, hackathons

Why was LinkedIn Events shut down? Why isn't there now a social network for business events?

2014-01-13T12:50:00+00:00

My answer to Why was LinkedIn Events shut down? Why isn't there now a social network for business events? on Quora

Our site Lanyrd offers LinkedIn signin and works as a social network for business and professional events. You can read more about our LinkedIn integration here: Use Lanyrd and LinkedIn to get more out of professional events and conferences

Tags: business, events, linkedin, networking, social-media, social-networks, quora

Calendars: When posting a facebook event page for an event that is repeated on two dates, should you use one page or two? (The events are games that are identical and should not have overlapping players)

2014-01-07T14:43:00+00:00

My answer to Calendars: When posting a facebook event page for an event that is repeated on two dates, should you use one page or two? (The events are games that are identical and should not have overlapping players) on Quora

I would use separate pages. The most valuable part of a Facebook event page is being able to see who is going to that event (and hence which of your friends will be there). If there are two events on two separate days you want to be able to maintain two separate lists of attendees.

Tags: calendars, events, facebook, games, startups, quora

How do I network with speakers at events?

2013-12-06T11:31:00+00:00

My answer to How do I network with speakers at events? on Quora

I've spoken at loads of conferences, and I can tell you that speakers WANT you to approach them. They're definitely interested in talking to you - that's one of the main reasons they speak.

Good speakers will hang around for the rest of the conference, and head to the after-party / bar afterwards. The initial rush of people after their talk almost always subsides within 20 minutes, so you should be able to talk to them later on without needing to queue.

There are a few exceptions: VCs might not be too keen on having everyone at an event pitching their startup - but generally you should expect that most speakers would be happy to talk to you.

Tags: events, networking, quora

Can Meetup be used to organize virtual events?

2013-11-26T18:05:00+00:00

My answer to Can Meetup be used to organize virtual events? on Quora

I don't think so. From http://help.meetup.com/customer/...

"Meetup is not a place for groups that ... Don’t meet face-to-face, such as a webinar, teleseminar, or conference call"

Tags: events, quora, meetup

Can I promote an online/virtual/ webinar event through Meetup?

2013-10-30T18:20:00+00:00

My answer to Can I promote an online/virtual/ webinar event through Meetup? on Quora

No. That's specifically mentioned as something Meetup should not be used for in their community guidelines: Meetup's Community Guidelines

"Meetup is not a place for groups that... Don’t meet face-to-face, such as a webinar, teleseminar, or conference call"

Tags: events, quora, meetup

Will it ever be possible to know all the variables involving a specific chaotic event, like the lottery numbers?

2013-10-29T16:08:00+00:00

My answer to Will it ever be possible to know all the variables involving a specific chaotic event, like the lottery numbers? on Quora

IANAP (I Am Not A Physicist) but my understanding of Heisenberg's uncertainty principle is that it is impossible to know both the exact position and the exact momentum of a particle at the same time. So no.

Tags: events, quora

Which event gave you a real happiness?

2013-10-28T12:07:00+00:00

My answer to Which event gave you a real happiness? on Quora

The Maker Faire in California, and the Mini Maker Faire in Brighton, UK. The enthusiasm for making things for the sake of making things is delightful and infectious.

Tags: events, quora

Who would like to help set up a Wordpress site that is event focused?

2013-10-23T13:38:00+00:00

My answer to Who would like to help set up a Wordpress site that is event focused? on Quora

Eventbrite (my employer) recently worked with WordPress.com to provide an integration between the two services which you may find relevant - it makes it very easy to set up a WordPress.com hosted site which ties in to the Eventbrite API to promote and enable ticket sales: WordPress.com Integrations for Eventbrite

Tags: events, web-development, wordpress, quora

What are some creative way-finding methods for events? Besides the usual signs.

2013-10-15T09:16:00+00:00

My answer to What are some creative way-finding methods for events? Besides the usual signs. on Quora

Add a venue map to the inside of the conference badge.

Why the inside? Because the badge should have the attendee's name on both sides, in case it flips over.

Adding a summary of the schedule to the badge (essentially turning the badge in to a little booklet) is a good idea too.

dConstruct in Brighton is a good example of an event with a well designed booklet badge - though as it is single track there's no need for a venue map.

(For a UX conference though if suggest that doing a really good job with the signs would be more appropriate than inventing a new, stylish but potentially less usable alternative to them).

Tags: events, quora

Other than CL, Yelp and Eventbrite, what are some good online event calendars to post to?

2013-09-18T17:53:00+00:00

My answer to Other than CL, Yelp and Eventbrite, what are some good online event calendars to post to? on Quora

Make sure you are listed on http://lanyrd.com/ - and don't forget to add you event's speakers and tag it with the relevant topics (e.g. http://lanyrd.com/topics/social-... )

Tags: conferences, events, quora

Event Planning: What are some useful books and resources on professional events and conference planning?

2013-09-18T16:39:00+00:00

My answer to Event Planning: What are some useful books and resources on professional events and conference planning? on Quora

http://www.quirksmode.org/coh/ is fantastic. It focuses on running small tech conferences, but there's plenty of advice in there that applies to all sizes of event.

Tags: conferences, events, quora

Event Planning: What can I do to protect myself from a keynote speaker not showing up?

2013-09-15T17:33:00+00:00

My answer to Event Planning: What can I do to protect myself from a keynote speaker not showing up? on Quora

My hunch is that if a keynote speaker doesn't show up it won't be for financial reasons - and they wouldn't expect their fee to be paid. Much more likely it would be a family emergency or unexpected travel problem.

Have you investigated event insurance?

Tags: events, quora

Events (leisure): What are the best places in San Francisco for organizing a small meetup?

2013-08-08T17:20:00+00:00

My answer to Events (leisure): What are the best places in San Francisco for organizing a small meetup? on Quora

If it's a technical event, there are dozens of tech companies with excellent facilities who might be convinced to host the event for free.

Tags: events, san-francisco, quora, meetup, sanfranciscobayarea

What are the most exciting sporting events in the world?

2013-08-04T14:26:00+00:00

My answer to What are the most exciting sporting events in the world? on Quora

That's easy... The Mongolian Golden Eagle Hunting Festival, held every October.

What do they hunt? Wolves!

http://m.travel.cnn.com/ireport/...

Tags: events, quora, sports

Events (leisure): How do you organize a conferencce?

2013-07-31T14:44:00+00:00

My answer to Events (leisure): How do you organize a conferencce? on Quora

Read http://www.quirksmode.org/coh/ - and good luck!

Tags: conferences, events, quora

How can I successfully organize a conference?

2013-07-29T11:59:00+00:00

My answer to How can I successfully organize a conference? on Quora

PPK's conference organisers handbook is crammed with useful advice on running this kind of event: http://www.quirksmode.org/coh/

Tags: business, conferences, events, quora, conference

Events (leisure): What platforms based on sharing/creating users' future plans with friends have been successful?

2013-07-21T12:35:00+00:00

My answer to Events (leisure): What platforms based on sharing/creating users' future plans with friends have been successful? on Quora

The founder of Plancast wrote an extensive post mortem discussing the challenges involved here:

http://www.techcrunch.com/2012/0...

A key challenge is that people don't tend to announce their plans more than a few days in advance, which means that the information they share has a very short shelf life during which it is useful.

We've managed to avoid that particular trap at http://lanyrd.com/ because people (in particular speakers) announce their participation in a conference months in advance - unlike social or entertainment events.

Tags: events, social-networks, quora, foursquare, plancast

What do you offer to a high-profile speaker when inviting him to an event?

2013-06-24T14:12:00+00:00

My answer to What do you offer to a high-profile speaker when inviting him to an event? on Quora

Unless they live locally it's almost rude not to offer flights and accommodation - they will certainly expect it.

If you want to make a really good impression, have someone pick them up at the airport and take them to their hotel. It can be a black car, but it's also a nice gesture if the event organiser does it personally.

For massive bonus points: provide them with a preloaded data SIM card (maybe even in a device that does tethering which they can borrow for the trip). Speakers from abroad will appreciate this enormously.

Have a speakers dinner at a good restaurant.

Don't be surprised if high profile speakers expect a speakers fee.

Tags: events, quora

What is the best conference welcome video you've ever seen?

2013-06-11T11:35:00+00:00

My answer to What is the best conference welcome video you've ever seen? on Quora

Webstock always have awesome opening titles. Here's their 2013 one: Webstock '13 opening - it's worth hunting around for previous years as well.

Tags: conferences, events, quora

What tech conferences will be taking place in Seattle the summer of 2013?

2013-06-03T18:00:00+00:00

My answer to What tech conferences will be taking place in Seattle the summer of 2013? on Quora

We have a list of upcoming (mostly tech) professional events and conferences in Seattle here: Conferences in Seattle | Conferences & Events | Lanyrd

You can subscribe to iCal or RSS feeds of that page to stay up to date with new events.

Tags: conferences, events, software-engineering, technology, quora, conference

What are some personalized ways to search for an event?

2013-06-01T14:23:00+00:00

My answer to What are some personalized ways to search for an event? on Quora

For conferences and professional events, try out our service http://lanyrd.com/ - if you sign in with Twitter (or LinkedIn) we'll show you events the people you are connected to are speaking at or attending, and we can make further recommendations based on your interest graph if you let us know which topics you are interested in.

Tags: conferences, events, quora

What should tech conferences, events and planners do to add diversity?

2013-06-01T10:17:00+00:00

My answer to What should tech conferences, events and planners do to add diversity? on Quora

JSConf did something very clever that helped them get 25% female speakers last year: Beating the Odds - How We got 25% Women Speakers for JSConf EU 2012

Their trick was to run an anonymous call for proposals, and then have a separate team go out and actively encourage people from under-represented groups to submit talks, and coach them to help them put together a great submission.

Read their article: it was a really successful strategy.

Tags: call-for-proposals, conferences, events, technology, quora, conference, diversity

What are the best web solutions available for coordinating people you send out for events?

2013-05-01T14:46:00+00:00

My answer to What are the best web solutions available for coordinating people you send out for events? on Quora

We recently released a product that solves exactly this problem. Lanyrd Pro is designed to help companies that promote themselves through attending, speaking at and sponsoring events co-ordinate their event strategy internally and promote it externally.

A key feature of the product is a private events calendar which pulls together information about what your team are already doing, and allows you to collect relevant events and annotate them with private notes and labels. Here's a screenshot:

We can provide a detailed breakdown of events your team have attended or spoken at in the past, highlight events with open calls for proposals, show you slides and videos from your team's presentations and help you plan your upcoming event strategy.

Our tools can also suggest events your team may want to attend based on your previous activity (and our huge database of professional events and conferences around the world).

The other half of the product is a branded, public page for communicating your event involvement to the outside world. Companies using the product for this include GitHub, Facebook Developers and Heroku. Here's a screenshot of one of our public-facing team pages:

You can find out more about our Pro product on our blog or in this presentation on SlideShare.

Tags: events, quora

What are some cool and cost-effective things to do for and at a wedding reception?

2013-05-01T10:04:00+00:00

My answer to What are some cool and cost-effective things to do for and at a wedding reception? on Quora

Lawn games! Croquet, pétanque, coits and the like. Cheap, fun, easy for people to pick up, won't ruin any suits and (at least for a UK wedding) traditional without being overly cheesey.

Tags: events, quora, weddings

How do conferences make money?

2013-02-27T11:16:00+00:00

My answer to How do conferences make money? on Quora

Ticket sales and sponsorships.

Tags: conferences, events, startups, quora, eventbrite

What are Startup Friendly Event Venues in Berlin?

2013-02-22T10:33:00+00:00

My answer to What are Startup Friendly Event Venues in Berlin? on Quora

We have a list of conference event venues in Berlin here (it's a semi-unreleased feature, so I'd love to get your feedback on if it helps solve your problem): Venues in Berlin | Lanyrd

At the moment we don't record things like the maximum capacity of a venue, but we DO show you other events that have run there in the past. You should be able to find a good venue for your event by keeping an eye out for venues that have hosted similar sized events, then researching those venues directly yourself.

Tags: events, quora