But first, we will unpack Apps and App platform economies within a mobile ecology of interfaces. Compared to most consumer software, an App is tiny. The Google Earth iOS App puts a genuinely total geography into your pocket for a mere 29.5 megabytes. <sup>42</sup> It can do this because most of the significant information that the App displays is stored, calculated, and served from the Cloud layer. The App is a thin membrane on top of a vast machine, but one that nevertheless allows its User to pilot and be piloted by that machine with the slightest gesture. It is at the intersection point between these two far more complex reservoirs of intelligence: the intentional User and the Cloud and Stack infrastructure on which the little App is perched. As that tiny membrane, it can synthesize and make useful vast continents of data and computational intelligence gathered from afar in the instance of a single User interaction, and so the real utility of a single piece of code that the App may contain vastly outleverages its relative parsimony. For this, an App condenses the Interface layer within the larger Stack, pitched between User and the Addresses that link the User to the Cloud, City, or environmentally embedded software. Within the governance logic of platforms, an App then transforms and translates some capacity of the Cloud, rendering and framing it for the User as an at-hand service. In turn it also draws the interactions of the User into a larger aggregation of data (e.g., location, path, preference), capitalizing their qualities and feeding the updated information back to the User in a virtuous loop. Whatever the App happens to be interfacing (geolocative routing, portable banking services, stored files, news or music streams, site-specific games) is provided to the User as a Cloud-based service. In that the service is provided to a device- User that is in motion, moving through the City layer and encountering different contexts on the go, the App platform provides that provisional link between a preexisting physical spatial context and this User-directed overlay of a Cloud service onto immediate circumstances. As discussed in the City layer chapter, there is then a kind of programmatic blending between the urban situation through which a User moves and the interactions he may be having with a specific App and Cloud service. A mall becomes a game board, a sidewalk becomes a banking center, a restaurant becomes the scene of a crime in a crowd-sourced recommendation engine, birds are angry and enemies are identified, and the experience of these may be very different for different people and purposes. At any given moment, multiple Users interacting with different Apps in the same place may have brought their shared location into contrasting Cloud dramas; one may be ensconced in a first-person shooter game and the other in measuring his carbon footprint, further fragmenting any apparent solidarity of the crowd. With billions of Users wielding mobile Apps at a time, and to varying degrees navigating their domains accordingly, it is certain that over time, physica habitats are also remade as architectural-scale Cloud hardware. They are not just where Cloud Polis works; they are a physical extension of it. As a blended coprogramming of space and software, habitat and habitus, the terrain modulates itself to the dictates of the navigation tool, a thin, User-facing membrane of a larger Cloud platform. The App is therefore not just the interface through which the User works on the world; it is also the aperture through which the Cloud (and The Stack) redraws the City and its Users.
Interface Layer
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