Application programming interfaces are what make location mashups easy to build. Google, Microsoft, and Yahoo each have APIs that developers can use to overlay virtually any kind of information on a map.
Yahoo offers Ajax and Flash versions of its APIs, and Yahoo was one of first of the big portals to embrace GeoRSS, an extension of the RSS standard that supports geographic data feeds. "We have exposed many of the raw materials needed for creating a mapping application on virtually any platform," including TVs and cell phones, says Jeremy Kreitler, director of Yahoo Maps.
If you're building an application that plots store locations on a map, Yahoo's Developers Network can help determine which APIs are best suited for the job. Yahoo also has an "application gallery" that showcases applications and mashups created using its mapping APIs. There's more to mashups than mapping, of course. Yahoo last year introduced APIs for building custom programs with its photo, calendar, shopping, and bookmark tools, too.
Microsoft provides mashup developers with visualization tools and geospatial Web services. Microsoft's Live Search Maps (maps.live.com) is a search and mapping site based on Microsoft Virtual Earth where people can get maps and directions, search for businesses and people, and create and share their collections or mashups.
Virtual Earth combines mapping and location Web services with aerial and satellite imagery. The two-dimensional portion of Virtual Earth allows for panning (moving left to right) and zooming into (magnifying) maps and imagery and scoping (defining boundaries) of search results within a map view.
Google, Microsoft, and Yahoo don't charge for use of their maps, but they require developers to adhere to strict terms and conditions. Maps that identify where people can buy illegal drugs or engage in other illegal activity are prohibited. Google also insists its API shouldn't be used to expose private information. If the terms and conditions are violated, Google has the right to suspend or terminate the mashup service.
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