nsIURIChecker
The URI checker is a component that can be used to verify the existence
of a resource at the location specified by a given URI. It will use
protocol specific methods to verify the URI (e.g., use of HEAD request
for HTTP URIs).
Initializes the URI checker. After this method is called, it is valid
to further configure the URI checker by calling its nsIRequest methods.
This method creates the channel that will be used to verify the URI.
In the case of the HTTP protocol, only a HEAD request will be issued.
| aURI | The URI to be checked. |
Begin asynchronous checking URI for validity. Notification will be
asynchronous through the nsIRequestObserver callback interface. When
OnStartRequest is fired, the baseChannel attribute will have been
updated to reflect the final channel used (corresponding to any redirects
that may have been followed).
Our interpretations of the nsIRequestObserver status codes:
NS_BINDING_SUCCEEDED: link is valid
NS_BINDING_FAILED: link is invalid (gave an error)
NS_BINDING_ABORTED: timed out, or cancelled
| aObserver | The object to notify when the link is verified. We will call aObserver.OnStartRequest followed immediately by aObserver.OnStopRequest. It is recommended that the caller use OnStopRequest to act on the link's status. The underlying request will not be cancelled until after OnStopRequest has been called. |
| aContext | A closure that will be passed back to the nsIRequestObserver methods. |
Returns the base channel that will be used to verify the URI.