Professional Ajax, 2nd Edition

10.1. The Rise of Mashups

Closely related to the various mapping APIs is the concept of a mashup. Mashups are web applications that combine information from a number of sources to provide a new user experience. This information isn't located at a single source; rather, it comes from numerous sources that publish information publicly through web services, RSS feeds, or other means. Traditionally, mashups involve combining such information with a map.

Chicago Crime (www.chicagocrime.org) is widely considered to be the first mashup, combining crime information for Chicago with a map generated by the Google Maps API. This site is credited with the rise of mashups as its developers integrated Google Maps long before the API was available. Over time, and through the use of the evolving Google Maps API, Chicago Crime has grown into a mashup covering nearly all aspects of crime in the Chicago area, with breakdowns by crime type, street, district, ward, and more.

Another popular first-mover in the realm of mashups was Housing Maps (www.housingmaps.com), which combines housing listings from Craig's List (www.craigslist.org) with a map generated by Google Maps. The map is used to show locations where there are listings as well as the addresses and photos of available properties.

To create a map-enabled mashup such as these, you must have access to location-based information. Most such information is represented by physical street addresses, such as those used to get directions. However, ...