The <RequestMapper> element configures the component used by the SP to map incoming requests to the configuration options that should be applied to them. You can think of it as a portable equivalent of the Apache <Location> feature, which associates Apache directives with portions of URLs. Like that feature, the request mapper operates based on URL, not on the physical paths of the underlying files, if any.
Another critical role of the request mapper is to map each request to the appropriate Shibboleth application, thereby connecting the resource-oriented settings to the more general behavior defined per-application as a unit.
While Apache-based deployments can, and usually should, rely entirely on Apache's functionality for this function, IIS provides no such capability. The request mapper allows the SP to insulate itself from the differences between servers.
Omitting this element will result in a "Native" plugin type with an empty/default configuration. This empty configuration maps all requests to the settings in the <ApplicationDefaults> section of the configuration, and adds no other settings, unless overridden by web server-specific options.
Two different types of Request Mapper are available: