Seattle Conference on Scalability: Scaling Google Maps from the big screen down to mobile phones
Jerry will talk about scaling Google Maps from the desktop down to mobile phones where usage is growing rapidly and will someday surpass desktop usage. He will discuss the approaches used in adapting the application to work in a low bandwidth, high latency environment with a wide variety of networks and devices. Mobile data rates currently range from 100 Kbps to 2 Mbps but more significantly, HTTP network request latency is measured in seconds. Mobile phone screens are very small compared to laptops, so we can't just shrink down the view. User input is often limited to 12-key keypads plus two soft keys, sometimes augmented with an alpha keyboard and/or a touch screen.
The key adaptation was reimplementing the AJAX web site as a client-server application, ported to several mobile platforms. We redesigned the user interface for the narrow UI bottleneck and added cellular-based location detection so people don't have to type an address just to get the map open to the right page. An application-specific network protocol and tile cache help with the high latency network by multiplexing requests together into fewer round trips. A special "mobile" tile set helps with latency and bandwidth by downloading smaller map tiles while offering more frequent road labels to suit tiny screens. Compression techniques such as a compact-header JPEG format for satellite images also help. The server is stateless so scaling up capacity is mostly handled by adding more servers. People are unaccustomed to downloading applications to their phones, and the phones have download limits, so it's important to keep the download package small. We also get the application preinstalled on some phones.
Speaker: Jerry Morrison
Jerry Morrison is a tech lead on Google Maps for mobile. He programs the server and clients in collaboration with teams in London, New York, Seattle, Tokyo, Beijing, and Cupertino. Jerry's career interest is bringing new forms of media to many people.
Google Tech Talks
June 14, 2008