APW - Apollo Phoenix Websocket


[Apollo] is a feature rich GQL client, APW implements an [Apollo GraphQL Network Layer] for it over [Phoenix Channels] allowing you to re-use a single bidirectional connection for executing your queries and mutations, the backend can send new data via subscriptions, and the Apollo client can update its internal store and update your views accordingly.

Since version 0.6.0, all Apollo operations are supported: queries, mutations, watchQueries (pooling) and
subscriptions.

Using the [Apollo Client], queries and mutations resolve to promises, and watchQueries and
subscriptions resolve to observables.

See the Apollo client [documentation][Apollo Client] for more info on how to invoke your GQL backend.

Installation

``shell
npm install --save apollo-phoenix-websocket
`

Usage

Just import the createNetworkInterface from APW and use it to create an ApolloClient.

The networkInterface function takes an options object, the only required
property is uri which specifies your endpoint websocket address.

`javascript
import ApolloClient from 'apollo-client'
import {createNetworkInterface} from 'apollo-phoenix-websocket'

// Nothing to configure if you are using an Absinthe backend
// Otherwise take a look at the Options section.
const networkInterface = createNetworkInterface({uri: 'ws://localhost:4000/socket'})

const apollo = new ApolloClient({networkInterface})
`

Options

Most likely, (as you are looking for a phoenix-websocket transport) you might be using
the [Absinthe] library to implement your Elixir GQL server. APW is configured by default
to work out of the box with an Absinthe backend.

But if need araises, you can supply some advanced options to customize how it works.
Here's is a commented example of the options that you can set for APW, with
their respective default values:


`javascript
createNetworkInterface({

// The websockets endpoint to connect to, like wss://example.com:4000/socket
uri: WS_URI,

// how to send queries and mutations
channel: {
topic: '__absinthe__:control',
event: 'doc',
},

// for using websocket subscriptions
subscription: (subscriptionResponse) => ({
topic: subscriptionResponse.subscriptionId,
event: 'subscription:data',

// extract the data from the event payload
map: payload => payload.result.data,

// what to do when unsubscribing
off: controlChannel => {
controlChannel.push('unsubscribe', {
subscriptionId: subscriptionResponse.subscriptionId
})
}
}),

// If you want to reuse an existing Phoenix Socket, just provide a function
// for APW to get it. By default, it will use the Phoenix Socket module.
Socket: options => new Socket(options),
})
`

Middlewares

You can use middlewares with use just like with
the standard apollo network interface. For example, a middleware can set authorization token on every request.

`javascript
networkInterface.use([{
applyMiddleware({request, options}, next) {
// Here you can modify the interface options, for example
// you can change the socket/channel that will handle the request
// For example for a channel expecting authenticated queries
options.channel.topic = "gql:restricted"
options.channel.params = {...paramsForTopicJoin}

// Or Modify the request
request.variables = {name: 'Luke'}

// Or Just add authorization token
request.context = {authorization: 'jwt_token'}

next()
}
}])
`

Afterware

You can use afterwares with useAfter just like the standard
apollo network interface. An example use-case is for error handling:

`javascript
networkInterface.useAfter([{
applyAfterware({response, options}, next) {
// throw an error that will trigger your error handler
if (response.error) {
throw new Error(response.error)
}
next();
}
}])
``

Absinthe backend

[Absinthe] is an amazing project (kudos to @benwilson512 et al.). It's actually very
simple to create a GQL backend with it.

Take a look at the following places for more information:

- The [Absinthe guide][Absinthe] itself for getting started.
- [Absinthe Phoenix] for implementing websocket subscriptions on your endpoint.
- [Absinthe.Schema#subscription/2][Absinthe Subscription] docs for how to setup your schema

Made with love <3

If you want to provide feedback or even better if you want to contribute some code feel free to open a [new issue].
Possible thanks to the awesome work of [our contributors].

[Apollo]: http://dev.apollodata.com/
[Apollo Client]: http://dev.apollodata.com/core/apollo-client-api.html
[Apollo GraphQL Network Layer]: http://dev.apollodata.com/core/network.html
[Phoenix Channels]: http://www.phoenixframework.org/docs/channels
[Absinthe]: http://absinthe-graphql.org/
[new issue]: https://github.com/vic/apollo-phoenix-websocket/issues
[our contributors]: https://github.com/vic/apollo-phoenix-websocket/graphs/contributors
[Absinthe Phoenix]: https://github.com/absinthe-graphql/absinthe_phoenix
[Absinthe Subscription]: https://hexdocs.pm/absinthe/1.4.0-beta.1/Absinthe.Schema.html#subscription/2