Seattle Conference on Scalability: Scaling Google Maps from the big screen do...

Google Tech Talks
June 14, 2008

ABSTRACT

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 adapt-
ing the application to work in a low bandwidth, high latency environment with a wide variety of net-
works 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 cel-
lular-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.

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