Microsoft Silverlight functionality is completely encapsulated within the Silverlight plug-in. Web applications typically require the server hosting the Web application to meet minimum requirements. Silverlight applications simply require a Web server to be equipped as they would be for hosting HTML documents. Silverlight applications can be hosted on any Web server accessible to the target audience. The two most commonly used Web servers are Microsoft Internet Information Server (IIS) and Apache.
Executing a Silverlight application on a Web client machine is a two step process. First, the application will detect if the Silverlight plug-in is installed on the Web client machine. If the plug-in is not installed, the user will be prompted with an option to download the plug-in. If the user opts to do so, a request will be made of the Web server to download and install the plug-in. The Silverlight plug-in is embodied in a .dll executable file that is loaded into the Web client browser memory once installed. The only interaction required by the Web client when installing the Silverlight plug-in is to grant permission for the plug-in to be installed. Various Web servers, including Microsoft Internet Information Server (IIS), may require slight configuration modifications so that the Silverlight executable file will be downloaded to the Web client when requested.
Second, once the Silverlight plug-in is installed on the Web client machine, the Silverlight application itself must be downloaded. A Silverlight application may consist of many types of files. Slight configuration modifications may be necessary on the Web server, such as MIME types, so that XAML and XAP files are associated with Silverlight and downloaded correctly to the Web client machine when requested.
Once the Silverlight plug-in is installed on a Web client machine and a Silverlight application is downloaded, the Silverlight application is then hosted on the Web client machine. There are some requirements necessary for the Web client machine as discussed in the sections below, however all media players, audio and video codecs, compilers and the runtime are encapsulated in the Silverlight plug-in.