What’s a web map context document?

It’s the end of the day, and you’ve spent the afternoon creating a map on your computer to use in a presentation tomorrow. You’ve selected a geographic region, a scale, a set of layers and the order in which those layers are displayed. You’ve customized the map to your liking, and will need to use the same view tomorrow.

However, you won’t be able to keep the browser window that is displaying the map alive. It is not practical for you to reassemble the layers, reorder them, and re-specify the scale and geographic region that was used to display the map when you get into work tomorrow.

What do you do to save your afternoon’s work?

You use a web map context document to record it. A Web Map Context (WMC) Document is a means of recording, or “bookmarking” a map view in an XML document. Using a WMC document, you can save and archive your favourite map views. You can also share WMC documents, or create a catalogue of WMC documents for searching.

The WMC document is a companion specification to the web map server specification. WMC documents allow users to save, reuse and share views of maps online and between applications. When you load a WMC document into a web map server client, the client will load the map based on a predefined set of viewing parameters. (Note that not all web map server clients currently support WMC documents. For a list of web map server clients that do support web map context documents, see OGC Resources for Registered Products.)

WMC documents are a client-side service. At this point, as there are no formal interfaces for web map service clients, different web map service clients implement WMC documents in different ways.

Note An SLD document and a WMC document are both produced in XML.