In this chapter, we learned about the various tools and techniques involved in developing geospatial applications that can be accessed via a web interface. We saw how web applications can be structured, learned that web application frameworks can simplify the process of building a web application, and saw how user-interface libraries make the job of implementing web applications much easier. We then looked at the concept of web services and saw how to implement a great-circle distance calculator as a web service. We also looked at how map rendering can be implemented as a web service and saw how tile caching can speed up the process of displaying maps within a web browser.

We next looked at the concept of slippy maps and saw how these can be built using a stack of off-the-shelf components. We also examined a number of common protocols for sharing and manipulating geospatial data.

Finally, we took an in-depth look at three particular tools and techniques that we will make use of in the remainder of this book: the Tile Map Service (TMS) protocol, the OpenLayers user interface library, and the GeoDjango web application framework.

In the next chapter, we will start to build a complete mapping application using PostGIS, Mapnik, and GeoDjango.