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| 20 | <li><a href="../index.html">Home</a></li> |
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| 21 | <li><a href="../introduction.html">For Users</a></li> |
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| 27 | <!-- ### Begin Content ### --> |
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| 28 | <div id="second"> |
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| 29 | |
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| 30 | |
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| 31 | |
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| 32 | <table class="rfc2822 docutils field-list" frame="void" rules="none"> |
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| 33 | <col class="field-name" /> |
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| 34 | <col class="field-body" /> |
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| 35 | <tbody valign="top"> |
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| 36 | <tr class="field"><th class="field-name">BEP:</th><td class="field-body">12</td> |
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| 37 | </tr> |
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| 38 | <tr class="field"><th class="field-name">Title:</th><td class="field-body">Multitracker Metadata Extension</td> |
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| 39 | </tr> |
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| 40 | <tr class="field"><th class="field-name">Version:</th><td class="field-body">10603</td> |
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| 41 | </tr> |
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| 42 | <tr class="field"><th class="field-name">Last-Modified:</th><td class="field-body"><a class="reference external" href="https://svn.bittorrent.com/trac.cgi/browser/dotorg/trunk/html/beps/bep_0012.rst">2008-02-07 17:54:09 -0800 (Thu, 07 Feb 2008)</a></td> |
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| 43 | </tr> |
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| 44 | <tr class="field"><th class="field-name">Author:</th><td class="field-body">John Hoffman <theshadow at degreez.net></td> |
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| 45 | </tr> |
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| 46 | <tr class="field"><th class="field-name">Status:</th><td class="field-body">Draft</td> |
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| 47 | </tr> |
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| 48 | <tr class="field"><th class="field-name">Type:</th><td class="field-body">Standards Track</td> |
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| 49 | </tr> |
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| 50 | <tr class="field"><th class="field-name">Created:</th><td class="field-body">07-Feb-2008</td> |
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| 51 | </tr> |
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| 52 | <tr class="field"><th class="field-name">Post-History:</th><td class="field-body"></td> |
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| 53 | </tr> |
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| 54 | </tbody> |
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| 55 | </table> |
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| 56 | <hr /> |
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| 57 | <div class="contents topic" id="contents"> |
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| 58 | <p class="topic-title first">Contents</p> |
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| 59 | <ul class="simple"> |
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| 60 | <li><a class="reference internal" href="#metadata-extension" id="id2">Metadata Extension</a></li> |
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| 61 | <li><a class="reference internal" href="#order-of-processing" id="id3">Order of Processing</a></li> |
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| 62 | </ul> |
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| 63 | </div> |
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| 64 | <div class="section" id="metadata-extension"> |
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| 65 | <h1>Metadata Extension</h1> |
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| 66 | <p>In addition to the standard "announce" key, in the main area of the |
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| 67 | metadata file and not part of the "info" section, will be a new key, |
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| 68 | "announce-list". This key will refer to a list of lists of URLs, and |
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| 69 | will contain a list of tiers of announces. If the client is compatible |
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| 70 | with the multitracker specification, and if the "announce-list" key is |
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| 71 | present, the client will ignore the "announce" key and only use the |
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| 72 | URLs in "announce-list".</p> |
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| 73 | </div> |
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| 74 | <div class="section" id="order-of-processing"> |
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| 75 | <h1>Order of Processing</h1> |
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| 76 | <p>The tiers of announces will be processed sequentially; all URLs in each |
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| 77 | tier must be checked before the client goes on to the next tier. URLs |
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| 78 | within each tier will be processed in a randomly chosen order; in other |
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| 79 | words, the list will be shuffled when first read, and then parsed in |
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| 80 | order. In addition, if a connection with a tracker is successful, it |
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| 81 | will be moved to the front of the tier.</p> |
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| 82 | <p>Examples:</p> |
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| 83 | <pre class="literal-block"> |
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| 84 | d['announce-list'] = [ [tracker1], [backup1], [backup2] ] |
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| 85 | </pre> |
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| 86 | <p>On each announce, first try tracker1, then if that cannot be reached, |
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| 87 | try backup1 and backup2 respectively. On the next announce, repeat |
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| 88 | in the same order. This is meant for when the trackers are standard |
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| 89 | and can not share information.</p> |
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| 90 | <blockquote> |
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| 91 | d['announce-list'] = [[ tracker1, tracker2, tracker3 ]]</blockquote> |
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| 92 | <p>First, shuffle the list. (For argument's sake, we'll say the list |
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| 93 | has already been shuffled.) Then, if tracker1 cannot be reached, try |
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| 94 | tracker2. If tracker2 can be reached, the list is now: |
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| 95 | tracker2,tracker1,tracker3. From then on, this will be the order the |
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| 96 | client tries. If later neither tracker2 nor tracker1 can be reached, |
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| 97 | but tracker3 responds, then the list will be changed to: |
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| 98 | tracker3,tracker2,tracker1, and will be tried in that order in the |
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| 99 | future. This form is meant for trackers which can trade peer |
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| 100 | information and will cause the clients to help balance the load |
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| 101 | between the trackers.</p> |
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| 102 | <blockquote> |
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| 103 | d['announce-list'] = [ [ tracker1, tracker2 ], [backup1] ]</blockquote> |
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| 104 | <p>The first tier, consisting of tracker1 and tracker2, is shuffled. |
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| 105 | Both trackers 1 and 2 will be tried on each announce (though perhaps |
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| 106 | in varying order) before the client tries to reach backup1.</p> |
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| 107 | </div> |
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