Microsoft Visio has had, for several versions, a useful Save As Web feature that creates a mini-website, complete with widgets for pan and zoom, Shape Data, and shape reports. This has worked best using the Vector Markup Language (VML) in Microsoft Internet Explorer, or in Scalable Vector Graphics (SVG) using a web browser plugin in IE, although it has native support in some other browsers. This is quite powerful, but it does require that the native Visio file is republished if any changes are made to the document. Visio 2010 has introduced the increasingly adopted XAML format, which actually means that the Visio file will be rendered for viewing in Silverlight. This is a very useful addition.
In addition, Microsoft has an ActiveX Visio Viewer control that can display native Visio files that are in both binary and XML format. This control is installed as default with Microsoft Outlook 2007+, but is also available as a separate free download from Microsoft. In fact, the Visio Viewer control has a programmable API that enables Shape Data to be extracted and exposed too. While this viewer has the advantage that the native file does not have to be republished, its reach is limited by the choice of browsers available, and the willingness to make the native Visio file accessible—this is not always the best strategy.
Microsoft Visio 2010 provides Visio Services for Microsoft SharePoint. Therefore, with rendering on the server, any client that accesses the Microsoft SharePoint site will have the ability to view Visio diagrams without having to install anything locally.
The user can interact with the diagrams by clicking on shapes to view the Shape Data, navigating any embedded hyperlinks, as well as pan/zoom and print capabilities. These are capabilities of the Save As Web and Visio Viewer options too.
Microsoft Visio 2007 introduced the ability to add a data recordset to a diagram and refresh the data so that the diagram could be kept up-to-date, but the Save As Web html pages and the Visio Viewer ActiveX control are not able to automatically respond to any data changes. Therefore, the diagram can quickly become outdated, thus requiring you to refresh the diagram in Visio, and then to republish it.
Now with Visio Services, that same data recordset can be refreshed by the server, thus providing everyone who views the diagram using the new Visio web part with the latest information. This is extremely nice, but be aware that there are some limitations, such as no shapes will be added, moved, or deleted in this operation, as only linked Shape Data and Data Graphics are updated and all layers will be visible. Still, you no longer have to republish just to refresh the data set!
Note
Visio has a complex layering system. Most CAD systems, for example, insist that all diagram elements belong to a single layer. This layer can either be made visible or not, or all elements on a layer have a specified color. Drawing elements in Visio can belong to none, one, or many layers! Visio Services, however, simply ignores layers.
