full-json-schema.json

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    "id": "blog.superfeedr.com:/null-device",
    "title": "Superfeedr's null device",
    "summary": "When subscribing to a feed, you should use https://push.superfeedr.com/dev/null if you want notifications to be ignored.",
    "content": "<p>Many people, us included, see the web being a complex <em>operating system</em>. A consequence of this is that we embrace the <a href=\"https://en.wikipedia.org/wiki/Unix_philosophy\">Unix philosophy</a> of small components loosely coupled using streams for data in and out.</p>\n\n<p>With that in mind, for subscribers, Superfeedr is mostly a piece of code which takes a feed URL as input, and a webhook URL as output to create <strong>subscriptions</strong> which triggers <strong>notifications</strong>.</p>\n\n<p>As <a href=\"http://blog.superfeedr.com/ways-to-use-superfeedr/\">we’ve seen recently</a>, once a subscription has been created, a user can then <a href=\"http://documentation.superfeedr.com/subscribers.html#retrieving-entries-with-pubsubhubbub\">retrieve</a> the content of the feed directly from us<sup id=\"fnref:1\"><a href=\"#fn:1\" class=\"footnote\">1</a></sup>.</p>\n\n<p>Now, if you go even further, there are cases where the user subscribes to a feed, but actually does not care about the notifications at all, because they just want to <em>retrieve</em> it from us. What happens to the callback url (webhook) then?</p>\n\n<p>On Unix systems, when you have an output that you want to ignore, your typically redirect it to the <a href=\"https://en.wikipedia.org/wiki/Null_device\">null device</a>: <code>/dev/null</code>:</p>\n\n<blockquote>\n  <p>The null device is typically used for disposing of unwanted output streams of a process, or as a convenient empty file for input streams. This is usually done by redirection.</p>\n</blockquote>\n\n<p>For example, if you wanted to fetch the home page of this blog to just get latency and bandwidth you would do something like<sup id=\"fnref:2\"><a href=\"#fn:2\" class=\"footnote\">2</a></sup>:</p>\n\n<pre data-line=\"\"><code class=\"language-bash\">$ curl &quot;http://blog.superfeedr.com/&quot; &gt; /dev/null\n  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current\n                                 Dload  Upload   Total   Spent    Left  Speed\n100  4871  100  4871    0     0  20901      0 --:--:-- --:--:-- --:--:-- 20905</code></pre>\n\n<p>The last part of this command tells the OS to send the content it’s downloading to <code>/dev/null/</code> which is another way to tell “just ignore it!”.</p>\n\n<p>So, using an identical approach, if you need to <strong>subscribe to a feed with Superfeedr but you actually do not care about the notifications</strong>, you can subscribe using this webhook URL: <a href=\"http://push.superfeedr.com/dev/null\"><code>https://push.superfeedr.com/dev/null</code></a> which is Superfeedr’s null device!</p>\n\n<div class=\"footnotes\">\n  <ol>\n    <li id=\"fn:1\">\n      <p>It’s important to create the subscription <em>before</em> so we keep polling the feed on the user’s behalf. <a href=\"#fnref:1\" class=\"reversefootnote\">&#8617;</a></p>\n    </li>\n    <li id=\"fn:2\">\n      <p>Yes, there are better ways to do so… and yes, <code>curl</code> as a <code>-o</code> option… but for the sake of using Unix approaches I wanted to show <code>&gt;</code>! <a href=\"#fnref:2\" class=\"reversefootnote\">&#8617;</a></p>\n    </li>\n  </ol>\n</div>",
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