The uri dispatcher is responsible for taking uri’s, determining
the content and routing the opened url to the correct content
handler.
When you encounter a url you want to open, you typically call
openURI, passing it the content listener for the window the uri is
originating from. The uri dispatcher opens the url to discover the
content type. It then gives the content listener first crack at
handling the content. If it doesn’t want it, the dispatcher tries
to hand it off one of the registered content listeners. This allows
running applications the chance to jump in and handle the content.
If that also fails, then the uri dispatcher goes to the registry
looking for the preferred content handler for the content type
of the uri. The content handler may create an app instance
or it may hand the contents off to a platform specific plugin
or helper app. Or it may hand the url off to an OS registered
application.
As applications such as messenger and the browser are instantiated,
they register content listener’s with the uri dispatcher corresponding
to content windows within that application.
Note to self: we may want to optimize things a bit more by requiring
the content types the registered content listener cares about.
@see the nsIURILoader class description
| aContentListener | The listener to register. This listener must implement nsISupportsWeakReference. |
OpenURI requires the following parameters…..
| aChannel | The channel that should be opened. This must not be asyncOpen'd yet! If a loadgroup is set on the channel, it will get replaced with a different one. |
| aFlags | Combination (bitwise OR) of the flags specified above. 0 indicates default handling. |
| aWindowContext | If you are running the url from a doc shell or a web shell, this is your window context. If you have a content listener you want to give first crack to, the uri loader needs to be able to get it from the window context. We will also be using the window context to get at the progress event sink interface. Must not be null! |
Loads data from a channel. This differs from openURI in that the channel
may already be opened, and that it returns a stream listener into which the
caller should pump data. The caller is responsible for opening the channel
and pumping the channel’s data into the returned stream listener.
Note: If the channel already has a loadgroup, it will be replaced with the
window context’s load group, or null if the context doesn’t have one.
If the window context’s nsIURIContentListener refuses the load immediately
(e.g. in nsIURIContentListener::onStartURIOpen), this method will return
NS_ERROR_WONT_HANDLE_CONTENT. At that point, the caller should probably
cancel the channel if it’s already open (this method will not cancel the
channel).
If flags include DONT_RETARGET, and the content listener refuses the load
during onStartRequest (e.g. in canHandleContent/isPreferred), then the
returned stream listener’s onStartRequest method will return
NS_ERROR_WONT_HANDLE_CONTENT.
| aChannel | The channel that should be loaded. The channel may already be opened. It must not be closed (i.e. this must be called before the channel calls onStopRequest on its stream listener). |
| aFlags | Combination (bitwise OR) of the flags specified above. 0 indicates default handling. |
| aWindowContext | If you are running the url from a doc shell or a web shell, this is your window context. If you have a content listener you want to give first crack to, the uri loader needs to be able to get it from the window context. We will also be using the window context to get at the progress event sink interface. Must not be null! |
Stops an in progress load
@name Flags for opening URIs.
Should the content be displayed in a container that prefers the
content-type, or will any container do.
If this flag is set, only the listener of the specified window context will
be considered for content handling; if it refuses the load, an error will
be indicated.