title: AWS AppSync Subscription Arguments
body: <p>What can the arguments on an AppSync GraphQL subscription be used for? According to the <a href="https://docs.aws.amazon.com/appsync/latest/devguide/real-time-data.html" rel="nofollow noreferrer">real-time data</a> page on the docs:</p>
  
  <blockquote>
    <p>An important part of using GraphQL subscriptions is understanding when and how to use arguments, as subtle changes will allow you to modify how and when clients are notified of mutations that have occured.
    (...)
    In the default sample, clients can subscribe to Comments when a specific eventId argument is passed through</p>
  </blockquote>
  
  <p>I can't find any way to access the subscription arguments, though. I have different 'channels' of comments that I'd like users to be able to subscribe to individually, optionally with a password. The subscription I've set up responds to comments in all channels instead.</p>
  
  <p>Is there any way to 'filter' the data coming through the subscription with a mapping template or similar? If not, what's the intended use of the subscription arguments? Must the filtering be done client side?</p>