The emergence of GraphQL over the past couple of years has changed the way people are thinking about API development and is reshaping the way engineering teams are structured by allowing front-end developers to move further up the stack and redefining traditional engineering roles. With the introduction of AWS AppSync, we can easily extend the possibilities of what GraphL is capable of, enabling a single GraphQL API to power entire applications by working with multiple data sources, microservices, and AWS Lambda functions. In this session, we show this architecture in action, walk through the design and implementation, and answer your questions as we dive deep.

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Best Practices in designing
GraphQL APIs that scale
Nader Dabit
Developer Advocate
AWS Mobile
M O B 4 2 0

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Think in Graphs
Model your business domain as
a graph

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Thinking in Graphs

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Authorization &
Fine-grained Access Control

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Traditional GraphQL API
todoItem = {
type: TodoItemType,
args: { id: { type: GraphQLID } },
resolve: (identity, {id}) => TodoItem.get(identity, id)
};
class TodoItem {
get(identity, id) {
// implementation
}
}

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AWS AppSync
{
"version" : "2017-02-28",
"operation" : "Query",
"index" : "author-index",
"query" : {
"expression": "author = :author",
"expressionValues" : {
":author" : {
"S": "${ctx.identity.sub}"
}
}
}
}

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Naming Matters

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Use Input Types

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Input Types
createUser(name: String!, address: String!, age: Int, address: String, gender: String):User
input CreateUserInput {
name: String!
address: String!
age: Int
address: String
gender: String
}
createUser(input: CreateUserInput):User
Without Input type
With Input type

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API Gateway

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API Gateway - Resolvers
Interesting use cases
Microservices
Dynamic delivery of image assets for AR / VR applications
Interacting with AI / ML services via a Lambda function
Turning an existing REST API into a GraphQL API

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Efficiency

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Reduce round trips to the backend
{
users {
name
city
friends(first: 10) {
name
}
}
}
GET:1
GET: friends: 1 : 10

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Writing your own API?
Use DataLoader by Facebook

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AWS AppSync - Batch Operations
#set($ids = [])
#foreach($id in ${ctx.args.ids})
#set($map = {})
$util.qr($map.put("id", $util.dynamodb.toString($id)))
$util.qr($ids.add($map))
#end
{
"operation" : "BatchGetItem",
"tables" : {
"Posts": { "keys": $util.toJson($ids) }
}
}

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Design for the future

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GraphQL VS REST
Rest GraphQL

29. Thank you!
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Nader Dabit
@dabit3

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