A core element of Web 2.0, mashups enable information sharing and interoperability by combining data from different external sources. With the adoption of web standards like RSS, online tools now allow the user to create and publish mash-ups with relative ease. Such tools are the Mapbuilder (tool for overlaying pin-points and tags over a map) and the Yahoo Pipes, with more sophisticated integration of various data sources. Both use cartographic and geographic data to produce a map; the user can then choose to add information related to location.
The produced examples have as intended audience the consumer. The Mapbuilder shows the locations of local sites in the island of Ikaria, Greece. The audience of Yahoo Pipes mashup could be someone interest in the world news with an option of accessing location related photos; this is achieved by overlaying the Reuters News RSS feed on a map using each story's location information, plus combining it with the Flicker Geo RSS service to produce a link on a relevant to location photo. There is a strong chance that the latest geo-tagged photo with a location same as the story will have relevant content though there is no guarantee of this.
Yahoo Pipes is a Javascript application with a visual interface that includes various tools referred to as modules. Each module can accept a data source as input, manipulate it, and pipe its output to a different module. The process follows the imperative programming paradigm: inputs and outputs can be processed using modules like the Loop operator (iterating over the result-feed of its input), String functions, URLBuilder etc. The final feed can be georeferenced by using the Location Extractor module; given a string that contains a place name it attaches GeoRSS standard spatial coordinates to it. Inherent ambiguity limits its accuracy; different places with the same name do exist. The output stream of data can be exported as JSON or RSS feed. Of particular interest, is the YQL module: using sql-like syntax the user can query and filter the content of an RSS feed. This feature is used on the example pipe. Finally, the RSS-Item Builder restructures the modified data sources as an RSS feed, which then can be piped to the output.
B.3 Usability, flexibility and extensibility
Both engines are easy to use for simple mashups, though Yahoo Pipes extended capabilities can challenge users with little or no programming experience. Additionally, Yahoo Pipes user interface is computationally demanding; integrating data from different web-services in the client machine proved a difficult task without reliable and fast internet connection, with errors related to connection refusal. According to Yahoo, there is an ongoing redesigning of the data flow engine based on the YQL functionality(3). Finally, Yahoo Pipes Badge allows the map output to be embedded in any web page by providing a widget with a guid; an excellent example of how GI mashups can add value to a website free of cost.
B.4 References
1. Map Builder url: http://www.mapbuilder.net/users/panoramix95/83622
2. Yahoo Pipes url: http://pipes.yahoo.com/gita_abhp626/reuter_news_and_flicker_photos
3. Pipes Blog » Blog Archive » Connection refused and other Pipes issues. Available at: http://blog.pipes.yahoo.net/2009/12/10/connection-refused-and-other-pipes-issues/
[Accessed April 7, 2010]
4. Pipe implementation screen shot
