Implementing a work in progress indicator for map layers

In the art of creating great applications, the most important thing to take into account is the user experience. A good application does what it must do, but by making the user feel comfortable.

When working with remote server, most of the time the user is waiting for data retrieval. For example, when working with a WMS layer, every time we change the zoom level, the user has to wait for some seconds till data is obtained from the server and the tiles start rendering.

It would be great to show some feedback to the users by using an icon, a progress bar, and so on, to inform that the application is working but needs some time.

This recipe shows how we can give some feedback to the user by informing when the application is loading content from different servers, making use of some layer events.

Note

Like in many other recipes in this book, we have used the Dojo toolkit framework (http://dojotoolkit.org) for a better user experience....