Federation Subscriptions

[mfulton26]

Is your feature request related to a problem? Please describe.

I want to use GraphQL Yoga as my Apollo Federation implementation but I want to use subscriptions too and from the [docs](https://the-guild.dev/graphql/yoga-server/docs/features/apollo-federation it looks like it isn't implemented yet. Apollo Federation used to not support subscriptions but it does now: https://www.apollographql.com/blog/announcement/backend/federated-subscriptions-in-graphos-real-time-data-at-scale/#subscriptions-meet-apollo-federation

Describe the solution you'd like

Subscriptions support in Yoga's Federation implementation.

Describe alternatives you've considered

Using Apollo instead of Yoga... that might be difficult in environments like Deno Deploy and I find Yoga more enjoyable to work with

Additional context

[n1ru4l]

We can use the new implementation @ardatan created in graphql-tools. It is a matter of updating our documentation.

[mfulton26]

It looks like the docs for yoga also state that @apollo/gateway only works with graphql@15 too but I think the latest version appears to have a peer dependency on graphql@16 so that may not be true anymore and the docs can be updated too.

[n1ru4l]

Yes, that ia true. We are still busy with conference work this week, but hope to get back to all of this stuff starting next week, so sorry for the delay!

[moloti]

Wundergaph Cosmo Federation Router is also supporting federation with subscription now. Maybe you can have a look at this: https://cosmo-docs.wundergraph.com/router/subscriptions

[ardatan]

GraphQL Yoga with @graphql-tools/federation supports subscriptions already; #3054
But if you are looking for a non-programmatic solution like Wundergraph but in JS, GraphQL Mesh also provides that