Horseshoes, hand grenades, and building mobile applications

The difference between location and proximity: knowing you’re in the restaurant vs knowing what table you’re sitting at.

As the old proverb goes, “close only counts in horseshoes and hand grenades.” It doesn’t quite apply when building mobile applications, however. Smaller screens and the resistance to extensive keyboard input define the input and output constraints of mobile apps, but there is something more fundamental that a mobile application can do. At its best, an application that knows where you are will augment reality to help you navigate and interact with the physical world. These applications are sometimes described as “location” applications and sometimes described as “proximity” applications. Many people are guilty of using the words interchangeably — myself included. In response to my post on iBeacon basics, Alasdair Allan called me out on Twitter:

His comment was spot-on. In this post, I’ll define (and be very precise about) the difference, the importance of which leads directly to the level of interest in proximity — and informs the excitement levels around technologies like iBeacons.

If you ask somebody for a location, you’ll likely get an answer based on varying distance scales: continent, country, time zone, state, province, city, or neighborhood. For the purpose of this post, location is a mid-scale answer to the question “where am I?” Initially, the answer to that question came from technologies like cell tower mapping or GPS, and the location was roughly equivalent to a street address. First-generation location applications can help you drive or walk to a building, find nearby events or restaurants, or check in for your visit. These are all powerful tools, and it is hard to remember that when I first moved to Silicon Valley, I found an apartment by getting a daily list faxed to me and looking up addresses on paper maps. Location is an important bit of context for searches. If I am standing on the street in San Francisco, I probably don’t want to learn about restaurants in Manhattan (or even San Jose).

Another way of looking at the answer to the question “where am I?” is that when you are talking to people not in the same building, the answer is likely to be the building or business you are in. If I’m meeting a co-worker for lunch, he cares about my location in terms of the restaurant, but he doesn’t need any additional information.

The next scale down from what I’ve called location is proximity, which is an even tighter description of where you are, and is a subset of location. Location would be the statement, “I am at B&H Photo in New York City.” Proximity would be the statement “I am standing near Canon digital SLRs.” Another way to think about the difference is that when emergency responders are coming to help you, they get to your location using motorized vehicles, but they can’t help you until they can get close enough to touch you.

Proximity services are based on a different set of technologies than location services. Rather than being large outdoor systems like cell networks or satellites, proximity is based on shorter-range technologies like Wi-Fi or Bluetooth Low Energy (the Bluetooth-based iBeacon, for instance). An important technical difference between the two classes of technology is that proximity technologies can be used indoors to provide the same types of services as large outdoor systems but on a smaller scale.

One of the most common proximity services described is mobile advertisements. When a device gets close to a display, a coupon can be pushed to the display. The basic capability of popping up relevant content has many additional applications. Museum guide apps can use proximity to draw visitors to major attractions and offer more information than signs can. Likewise, tickets can automatically be displayed for validation, whether as you approach an airport gate or a train conductor approaches you.

More fundamentally, though, is that proximity brings customers into business processes, and the efficiency can benefit everybody. In a recent discussion I had with David Helms of Radius Networks, he gave the example of a quick-service restaurant chain. Typically, such a restaurant will have counters with long lines, and there are multiple waiting steps in the typical dining experience: first stand in line, then wait for food to be prepared, then find a table. Alternatively, technology today allows customers to order by smartphone, perhaps even on the way to the restaurant. Proximity comes into play when the phone enters the restaurant. Rather than place the order directly with the kitchen when the customer finishes, the order can be held until the customer arrives; the act of walking in the door automatically initiates the order preparation process. In Helms’ example, if each table also has a proximity sensor, the restaurant can even be notified precisely where to deliver the freshly prepared meal.

Location and proximity are raw capabilities that provide important context for mobile application developers. As I continue writing about what this means for developers, we’ll look at the tools available on mobile operating systems to build the next wave of great applications.

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