WIP: Support for new graphql-js subscriptions support

[Urigo]

Background

Based on graphql-js with support for subscriptions (graphql/graphql-js#846) with AsyncIterator.

Changes

• Removed most of the previous code.
• Removed SubscriptionManager and it's execute logic.
• PubSub remains the same, but with support for asyncIterator conversion.

Usage Examples

Simple Example

import { PubSub } from `graphql-subscriptions`;

const pubsub = new PubSub();

const resolvers = {
     Subscriptions: {
         commentAdded: {
              subscribe: () => pubsub.asyncIterator('newComment'),
         }
     }
}

pubsub.publish('newComment', { commentAdded: { ... });

Mapping Channels

Mapping channels is simpler now: the GraphQL subscriptions is not related to the PubSub events directly by name. That means that you can use any publication name you want - as long you use it as return value in your subscribe resolver.

Multiple Channels

Just like a single channels mapping, you can pass an array of channels names:

pubsub.asyncIterator(['newComment', 'updatedComment']),

Filters

Filters is important when using subscriptions, and in this new version, the filter is closer to the actual resolver implementation.
You can write your filter and use withFilter over your existing AsyncIterator:

const resolvers = {
  Subscription: {
    commentAdded: {
      subscribe: withFilter(pubsub.asyncIterator('commentAdded'), (payload, args) => {
        return payload.commentAdded.repository_name === args.repoFullName;
      }),
    },
  },
}

[leebyron]

As you write about using AsyncIterator - I think IxJS is a great resource for working with them.