Proposal: GraphQL Composite Schemas Working Group (#977)

* GraphQL Composite Schemas RFC

* Update CompositeSchemas.md

* Added Michael Staib

* Add Matteo

Co-authored-by: Matteo Collina <matteo.collina@gmail.com>

* Update bullets based on feedback

* Add interested parties that have attended a GraphQL WG recently

* Add Nadel to examples

Co-authored-by: Michael Staib <michael@chillicream.com>
Co-authored-by: Matteo Collina <matteo.collina@gmail.com>

rfcs/CompositeSchemas.md

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+# RFC: GraphQL Composite Schemas
+
+There's a _lot_ of different ways of combining multiple GraphQL schemas together to form a larger composite schema, and the wide variety of options can make it challenging to design schemas in a way that will be easy to compose later. To name but a few approaches:
+
+- Schema merging and stitching (various implementations in many languages)
+- GraphQL modules and other "extend type"-based approaches
+- Federation (Apollo's v1 and v2, Mercurius, WunderGraph, Hot Chocolate, etc)
+- Hasura's GraphQL Joins
+- Atlassian's Nadel
+
+Though these are all separate solutions to similar problems, there are various concerns that most of them have to consider:
+
+- Identifying the schemas to join
+- Discovering/defining the relationships between the types/schemas
+- Schema manipulation to avoid conflicts (e.g. renaming types/fields)
+- Resolving questions around type "ownership", redundancy and/or sharing; detecting conflicts
+- Detecting breaking changes
+- Actually fetching the relevant data, and combining it to fulfil the GraphQL request
+- Managing composition metadata with respect to handling the above concerns
+- etc
+
+It feels like it would be of benefit to the ecosystem at large if there were a shared specification that covers a few of these needs.
+
+If this is of interest to you, please enter your name, GitHub handle, and organization below:
+
+| Name              | GitHub        | Organization     | Location            |
+| :---------------- | :------------ | :--------------- | :------------------ |
+| Benjie Gillam     | @Benjie       | Graphile         | Chandler's Ford, UK |
+| Yaacov Rydzinski  | @yaacovCR     | Individual       | Neve Daniel, IL     |
+| Roman Ivantsov    | @rivantsov    | Microsoft        | Redmond, WA, US     |
+| Tim Suchanek      | @timsuchanek  | GraphCDN         | Berlin, DE          |
+| Saihajpreet Singh | @saihaj       | The Guild        | Ottawa, ON, CA      |
+| Matteo Collina    | @mcollina     | NearForm         | Forlì, IT           |
+| Uri Goldshtein    | @urigo        | The Guild        | Tel Aviv, IL        |
+| Marc-Andre Giroux | @xuorig       | Netflix          | Montreal, Canada    |
+| Praveen Durairaju | @praveenweb   | Hasura           | Bangalore, India    |
+| Hugh Willson      | @hwillson     | Apollo           | Ottawa, ON, CA      |
+| Michael Staib     | @michaelstaib | ChilliCream Inc. | Zurich, CH          |