RoutePolicy, part of Webapp, is a low-level API for declaring the offline access semantics that apply to portions of the app's URL space. This is information is necessary when generating HTML5 Appcache manifests.
For example, DDP uses sockjs to emulate
websockets when they are not available. sockjs emulates websockets
using HTTP long polling, and it uses URLs under /sockjs to perform
this long polling. So the ddp
package uses RoutePolicy to declare that the /sockjs route is of
type "network" and should always be fetched live from the Internet and
never included in the appcache.
For more information, see the comments in the source.