netwerk/base/nsIIncrementalDownload.idl

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim:set ts=2 sw=2 sts=2 et cindent: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "nsIRequest.idl"
   8
   9 interface nsIURI;
  10 interface nsIFile;
  11 interface nsIRequestObserver;
  12
  13 /**
  14  * An incremental download object attempts to fetch a file piecemeal over time
  15  * in an effort to minimize network bandwidth usage.
  16  *
  17  * Canceling a background download does not cause the file on disk to be
  18  * deleted.
  19  */
  20 [scriptable, uuid(6687823f-56c4-461d-93a1-7f6cb7dfbfba)]
  21 interface nsIIncrementalDownload : nsIRequest
  22 {
  23   /**
  24    * Initialize the incremental download object.  If the destination file
  25    * already exists, then only the remaining portion of the file will be
  26    * fetched.
  27    *
  28    * NOTE: The downloader will create the destination file if it does not
  29    * already exist.  It will create the file with the permissions 0600 if
  30    * needed.  To affect the permissions of the file, consumers of this
  31    * interface may create an empty file at the specified destination prior to
  32    * starting the incremental download.
  33    *
  34    * NOTE: Since this class may create a temporary file at the specified
  35    * destination, it is advisable for the consumer of this interface to specify
  36    * a file name for the destination that would not tempt the user into
  37    * double-clicking it.  For example, it might be wise to append a file
  38    * extension like ".part" to the end of the destination to protect users from
  39    * accidentally running "blah.exe" before it is a complete file.
  40    *
  41    * @param uri
  42    *        The URI to fetch.
  43    * @param destination
  44    *        The location where the file is to be stored.
  45    * @param chunkSize
  46    *        The size of the chunks to fetch.  A non-positive value results in
  47    *        the default chunk size being used.
  48    * @param intervalInSeconds
  49    *        The amount of time to wait between fetching chunks.  Pass a
  50    *        negative to use the default interval, or 0 to fetch the remaining
  51    *        part of the file in one chunk.
  52    */
  53   void init(in nsIURI uri, in nsIFile destination, in long chunkSize,
  54             in long intervalInSeconds);
  55
  56   /**
  57    * The URI being fetched.
  58    */
  59   readonly attribute nsIURI URI;
  60
  61   /**
  62    * The URI being fetched after any redirects have been followed.  This
  63    * attribute is set just prior to calling OnStartRequest on the observer
  64    * passed to the start method.
  65    */
  66   readonly attribute nsIURI finalURI;
  67
  68   /**
  69    * The file where the download is being written.
  70    */
  71   readonly attribute nsIFile destination;
  72
  73   /**
  74    * The total number of bytes for the requested file.  This attribute is set
  75    * just prior to calling OnStartRequest on the observer passed to the start
  76    * method.
  77    *
  78    * This attribute has a value of -1 if the total size is unknown.
  79    */
  80   readonly attribute long long totalSize;
  81
  82   /**
  83    * The current number of bytes downloaded so far.  This attribute is set just
  84    * prior to calling OnStartRequest on the observer passed to the start
  85    * method.
  86    *
  87    * This attribute has a value of -1 if the current size is unknown.
  88    */
  89   readonly attribute long long currentSize;
  90
  91   /**
  92    * Start the incremental download.
  93    *
  94    * @param observer
  95    *        An observer to be notified of various events.  OnStartRequest is
  96    *        called when finalURI and totalSize have been determined or when an
  97    *        error occurs.  OnStopRequest is called when the file is completely
  98    *        downloaded or when an error occurs.  If this object implements
  99    *        nsIProgressEventSink, then its OnProgress method will be called as
 100    *        data is written to the destination file.  If this object implements
 101    *        nsIInterfaceRequestor, then it will be assigned as the underlying
 102    *        channel's notification callbacks, which allows it to provide a
 103    *        nsIAuthPrompt implementation if needed by the channel, for example.
 104    * @param ctxt
 105    *        User defined object forwarded to the observer's methods.
 106    */
 107   void start(in nsIRequestObserver observer,
 108              in nsISupports ctxt);
 109 };