nsIChannel Interface

 The URI corresponding to the channel.  Its value is immutable.

readonly attribute nsIURI URI

 The character set of the channel's content if available and if applicable.
 This attribute only applies to textual data.

 The value of the contentCharset attribute is a mixedcase string.

attribute ACString contentCharset

 The length of the data associated with the channel if available.  A value
 of -1 indicates that the content length is unknown.

 Callers should prefer getting the "content-length" property
 as 64-bit value by QIing the channel to nsIPropertyBag2,
 if that interface is exposed by the channel.

attribute long contentLength

 The MIME type of the channel's content if available. 
 
 NOTE: the content type can often be wrongly specified (e.g., wrong file
 extension, wrong MIME type, wrong document type stored on a server, etc.),
 and the caller most likely wants to verify with the actual data.

 Setting contentType before the channel has been opened provides a hint
 to the channel as to what the MIME type is.  The channel may ignore this
 hint in deciding on the actual MIME type that it will report.

 Setting contentType after onStartRequest has been fired or after open()
 is called will override the type determined by the channel.

 Setting contentType between the time that asyncOpen() is called and the
 time when onStartRequest is fired has undefined behavior at this time.

 The value of the contentType attribute is a lowercase string.  A value
 assigned to this attribute will be parsed and normalized as follows:
  1- any parameters (delimited with a ';') will be stripped.
  2- if a charset parameter is given, then its value will replace the
     the contentCharset attribute of the channel.
  3- the stripped contentType will be lowercased.
 Any implementation of nsIChannel must follow these rules.

attribute ACString contentType

 The notification callbacks for the channel.  This is set by clients, who
 wish to provide a means to receive progress, status and protocol-specific 
 notifications.  If this value is NULL, the channel implementation may use
 the notification callbacks from its load group.  The channel may also
 query the notification callbacks from its load group if its notification
 callbacks do not supply the requested interface.
 
 Interfaces commonly requested include: nsIProgressEventSink, nsIPrompt,
 and nsIAuthPrompt/nsIAuthPrompt2.

 When the channel is done, it must not continue holding references to
 this object.

 NOTE: A channel implementation should take care when "caching" an
 interface pointer queried from its notification callbacks.  If the
 notification callbacks are changed, then a cached interface pointer may
 become invalid and may therefore need to be re-queried.

attribute nsIInterfaceRequestor notificationCallbacks

 The original URI used to construct the channel. This is used in
 the case of a redirect or URI "resolution" (e.g. resolving a
 resource: URI to a file: URI) so that the original pre-redirect
 URI can still be obtained.  This is never null.  Attempts to
 set it to null must throw.

 NOTE: this is distinctly different from the http Referer (referring URI),
 which is typically the page that contained the original URI (accessible
 from nsIHttpChannel).

attribute nsIURI originalURI

 The owner, corresponding to the entity that is responsible for this
 channel.  Used by the security manager to grant or deny privileges to
 mobile code loaded from this channel.

 NOTE: this is a strong reference to the owner, so if the owner is also
 holding a strong reference to the channel, care must be taken to 
 explicitly drop its reference to the channel.

attribute nsISupports owner

 Transport-level security information (if any) corresponding to the channel.

readonly attribute nsISupports securityInfo