VSTO's deployment system affords the ease of updating found traditionally in Web-based applications without squandering the power of the rich client or compromising the strong Office offline story. The key to understanding how the deployment system works is understanding the relationship between application manifests embedded in the document and deployment manifests stored on servers. The application manifest refers to the deployment manifest, which then points to the most recent copy of the application manifest and, hence, the customization.
VSTO also supports local install scenarios without deployment manifests. By default, the customization loads out of the same directory as the document, but you can edit the embedded application manifest to point to a central machine location (such as the user's Program Files directory). Custom installation classes can use the ServerDocument object model to edit embedded application manifest information much as you would edit embedded cached data in the data island.
This chapter completes our look at the fundamentals of VSTO projects using Word and Excel. The final four chapters examine some advanced topics, such as using XML data with Word and Excel, and creating application-level managed add-ins for Word, Excel, and Outlook.