Introduction
TipThe Hello Viewer sample, in the Developer’s Guide samples, demonstrates concepts from this chapter.

The MapGuide Viewer is a browser-based method for displaying map data in a MapGuide application. It is a complete application, with support for standard mapping functionality like zooming, theming, and selecting features. There are two different versions of the Viewer:

- DWF Viewer, which runs only within Internet Explorer, and requires a browser plug-in
- AJAX Viewer, which runs within Internet Explorer, Mozilla Firefox, and Safari, without requiring a browser plug-in

As much as possible, the two versions of the Viewer operate in the same way, so deciding which to use depends on the needs of the application. If all the end users of the application use Internet Explorer, the DWF Viewer my be an appropriate choice, but if some of them use a different browser the AJAX Viewer is a better choice.

Most MapGuide applications use a Viewer, though it is possible to create applications that perform data analysis or manipulation but do not display using the Viewer. For example, a MapGuide application can be used as a back-end to another mapping application.

The standard Viewer displays a map along with the following optional components surrounding the map:

- Tool bar
- Layers pane
- Properties pane
- Status bar
- Task bar
- Task list (normally hidden, but available as a drop-down from the task bar)
- Task pane
- Context (right-click) menu
- Zoom slider (AJAX Viewer only)

MapGuide Viewer

The tool bar, task list, task pane, and context menu can contain a combination of pre-defined and custom MapGuide commands.

A web layout defines how the Viewer looks and operates for a map. One function of a web layout is to define which optional components display with the map. All of the optional components can be disabled, leaving just the map itself.

The web layout also defines any custom functionality added to the web page through custom commands.

#### Topics in this section

- Custom Commands