srinivasankavitha
commented
6 months ago It looks like the PR you created in federation-jvm adds implements support for Http callback protocol for spring-graphql projects. We are currently working on integrating with spring-graphql in the DGS framework. I expect this feature would be available for free when that is released later this quarter. Rather than reimplementing this same logic in the framework, it would be preferable to leverage what is in the federation-jvm library already.
On Mon, Jan 8, 2024 at 3:08 PM Dariusz Kuc @.***> wrote:
Describe the Feature Request
GraphQL subscriptions enable clients to receive continual, real-time updates whenever new data becomes available. Unlike queries and mutations, subscriptions are long-lasting. This means a client can receive multiple updates from a single subscription.
WebSocket is the most commonly used subscription mechanism but it comes with few drawbacks - most notably it requires long lasting open connections. Apollo Router supports subscriptions using both the WebSocket and HTTP callback https://www.apollographql.com/docs/router/executing-operations/subscription-callback-protocol/ mechanism. HTTP callback protocol allows GraphQL servers to asynchronously send their subscription updates using regular HTTP POST requests which in turn allows you to scale you servers more easily.
HTTP callback protocol flow https://www.apollographql.com/docs/router/executing-operations/subscription-callback-protocol/
- initialization
- router generates new unique subscription ID
- routers sends subscription operation with additional extension data using regular HTTP POST request
- subgraph responds with a check message
- router responds with HTTP 204 (if successful)
- subgraph responds with empty { "data": null } GraphQL response
- main loop (run on some background thread)
- subgraph sends heartbeats every X milliseconds (if enabled)
- whenever new data is available, subgraph sends next message followed by complete message at the end of the stream
See also:
- federation-jvm spring-graphl implementation of the protocol [link https://github.com/apollographql/federation-jvm/pull/354 fix https://github.com/apollographql/federation-jvm/pull/360]
Describe Preferred Solution
DGS provides out of the box support for subscriptions using HTTP callback protocol. Describe Alternatives
WebSocket based subscriptions are still viable option but don't scale as nicely.
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dariuszkuc
gwardwell
paulbakker
Describe the Feature Request
GraphQL subscriptions enable clients to receive continual, real-time updates whenever new data becomes available. Unlike queries and mutations, subscriptions are long-lasting. This means a client can receive multiple updates from a single subscription.
WebSocket is the most commonly used subscription mechanism but it comes with few drawbacks - most notably it requires long lasting open connections. Apollo Router supports subscriptions using both the WebSocket and HTTP callback mechanism. HTTP callback protocol allows GraphQL servers to asynchronously send their subscription updates using regular HTTP POST requests which in turn allows you to scale you servers more easily.
HTTP callback protocol flow
checkmessage{ "data": null }GraphQL responsenextmessage followed bycompletemessage at the end of the streamSee also:
federation-jvmspring-graphlimplementation of the protocol [link fix]Describe Preferred Solution
DGS provides out of the box support for subscriptions using HTTP callback protocol.
Describe Alternatives
WebSocket based subscriptions are still viable option but don't scale as nicely.