Developing for a worst-case scenario

A common practice is to design for the happy path, a scenario where everything works correctly and according to plan. These scenarios tend to paint an overly optimistic picture of the real world. When the happy path meets real-world problems, the charade is over and the app must undergo serious revision or a rewrite.

This is bad for a number of reasons. Obviously, rewriting an app is costly. One of the tenets of good software development is to fail quickly and rapidly. If you finish your app, only to find that it doesn't work as advertised, you've failed far too late. Even if you don't have to rewrite the app, bolting on fixes to address fundamental problems with the underlying architecture can cause bugs that tend to linger until the inevitable rewrite.

The alternative is to start by designing for a worst-case scenario. Worst-case scenarios are more representative of the real world so apps are more likely to behave as you expect. These scenarios tend to be harder to solve but result in a robust solution that covers more edge cases. As a worst-case scenario is a superset of the happy path, you get two solutions for the price of one.

This strategy can be employed in many other areas, such as security, responsive web design, accessibility, and performance. The approach is simple. Pick one or more worst-case scenarios that impact your app the most and build with these scenarios in mind. A worst-case scenario is an excellent constraint. The more constraints you add, the easier it is to design a great solution.

So, what is an offline user experience? We can boil down the principles from Susan's list in the previous section to form a concise definition:

An offline user experience bridges the gap between online and offline contexts by providing equivalent functionality and content to the extent that technology and the laws of physics will allow.

To design this experience, it's vital to understand the pain and frustration that people encounter every day. There are a million ways to build an offline-first experience, but the correct solution is formed by the needs of your audience. The story in the previous section was one example but you can find an infinite number of scenarios. Once you know who you're developing for and their pain points, devising a solution is much simpler.

Let's go through a few more offline scenarios to get you going. Once you start thinking about who your audience is, write scenarios such as these to describe how the offline experience impacts them. Talk to people. Observe them in the real world. Do research to see what others have found. These are all the things that can help you build a more accurate picture of your target audience.

Going on an off-the-grid vacation

Once a year, Carl disappears into the wilderness for a two-week trek along the Pacific Crest Trail in the Western United States. He does this to get away from technology. However, sometimes, due to the nature of his job, he has to respond to an important e-mail or take the occasional phone call.

There is no cellular coverage out in the pines. To connect, Carl has to leave the forests behind and hitch a ride to the nearest hotel. After a hot shower and some real food, he powers up his Android and endures shoddy hotel Wi-Fi for the evening. It's an inconvenience but a compromise that Carl is willing to accept.

Living in a third-world country

Marsha owns an old Nokia phone with an i9 keypad. She has access to a slow GPRS network, which often goes down. As modern websites are so bandwidth-intensive, her phone so slow, and online connectivity so tenuous, she turns off images and media when she browses.

In the next town, the mobile network is slightly better but it's a five-mile walk. When Marsha needs to e-mail photos, she composes draft e-mails and queues them on her phone. Once a week, she treks into town to deliver milk from their small herd of cattle. During this time, she is able to send those e-mails. It's a slow and frustrating experience but she can't do much about it.

Commuting on public transportation

Elizabeth travels on a bus for an hour each way on her daily commute. The bus doesn't have Wi-Fi and encounters several dead zones on the route. She is a dedicated bibliophile, so these routes are a great opportunity to feed her reading addiction. As she reads 1-3 books a week, she often runs out of reading material.

When this happens on the bus, she can't usually do anything about it. Her life is so busy that she mostly doesn't have time to think about downloading new books before her commute. Maybe she'll bring a paperback along next time for something to do.

Working on a Wi-Fi only device

Shawon is 14. On his last birthday, his parents bought him an iPod touch. He wanted an iPhone for the coolness factor, but, oh well. It's fine. It doesn't have GPS or a mobile plan but most of the time, it's as good as a real iPhone.

Like most kids, he relies on his parents for transportation and accompanies them on their errands. As he has a Wi-Fi only device, he often goes somewhere new, only to have to figure out what the Wi-Fi password is—if the place even has Wi-Fi. There aren't many Wi-Fi networks without passwords these days.

When he can't find the password, he has to stay contented with the games and music that are on his device. However, most of his games require an Internet connection, which is odd, particularly for games with a single-player mode.

Sharing files between mobile devices

Francine likes her world where file sharing is so easy and seamless. In 2005, you used USB drives. In 2015, you share files wirelessly, with technology and services such as Dropbox, Google Drive, and Airdrop. Unfortunately, when her Internet connection dies, she's transported back to 2005.

Just last week, her editor asked for an update to an outline that she wrote. Traveling at the time, she didn't have easy access to Wi-Fi. She made the changes on her laptop but couldn't transfer the file to her phone in order to be e-mailed. After struggling with this for several minutes, her Airbnb host replied with instructions to connect to the network. Crisis averted.

Streaming a high-definition video from YouTube

Brian streams online videos, a lot. Most of this streaming is over his phone. His mobile provider is kind of horrible, so he has to deal with dodgy Internet connectivity. Most of the time, YouTube is very good about decreasing the quality of the videos to compensate for bad network conditions, but it isn't always enough.

He wishes there was a way to get a transcription of the video or just wait for the entire thing to download before playing it. YouTube won't download an entire video when it's paused. Unfortunately, these features don't exist. Instead, Brian bookmarks the videos to watch at home.

Online shopping with your phone

Jasmine is not an organized person. She likes taking care of things in the moment, as they come to mind. As a busy professional, she doesn't have the mental resources to memorize lists and doesn't want to be tied to a to-do app or sheet of paper.

Shopping is one example. Throughout her day, she does a mental inventory as she moves about. When she spots an item in short supply, she grabs her phone and places an order with her Amazon app. When she's connected to the Internet, this works great. When she's not, it frustrates her that she can't take care of things. If only Amazon provided a better add-to-cart experience for people who want to buy things while offline.

Getting work done at a conference

Conferences are notorious for their abysmal Wi-Fi. Raphael is attending Whole Design, along with 1,500 other attendees. It's a three-day, single-track conference. On day two, with four hours to go, he is ready to be done fighting for bandwidth. He hasn't gotten much done beyond seeing some great talks. Even his cell phone, normally reliable, doesn't work here at all.

Every couple of hours, the attendees get a 30-minute break. Raphael uses these opportunities to sprint outside the venue. Here, he can get a solid 3G connection. This is enough to check his e-mail and chats and generally check in with his world. At least, it should be. His apps behave as though there's a binary switch between no bandwidth at all and enough to stream an HD video. A third option would be nice.