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Introduction to GraphQL in Scala (ScalaMatsuri 2017)
GraphQL is a query language that provides an alternative to REST APIs. It allows clients to fetch multiple resources with a single request by defining the desired resources in the query. This is more efficient than making separate requests in REST for each resource. While GraphQL reduces the number of requests, it requires defining object schemas and writing long queries in a string format, which some find difficult. The presenter's company tested GraphQL but ultimately decided to keep using REST due to these downsides.
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Introduction to GraphQL in Scala (ScalaMatsuri 2017)
- 1. Introduction to GraphQL inScala Yuki Katada ScalaMatsuri 2017 Scalaで始めるGraphQL
- 2. About Me Name • YukiKatada (片田雄樹) Affiliation • CyberAgent, Inc. • Media Development Headquarters (メディアディベロップメント事業本部) Scala Experience • One and a half years Follow Me • On Twitter @ponyoky ← very few ppl are following me :( 自己紹介
- 3. Our Job • Weare developing Advertising Network, which delivers Ads to multiple media such as CyberAgent “Ameba”. • Approximate 700 users are using our product. • Our product has more than 600 million incoming traffics per day • We are using GraphQL at Admin Page, which requires complex queries 我々のプロダクトはAmebaメディアに対する広告を配信するシ ステムで、その管理画面部分でGraphQLを使用しています。
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- 5. What is GraphQL? GraphQLis a query language, which is developed by Facebook. It provides an alternative to REST. (Not Graph DB) Some GraphQL libraries are provided as following: • Javascript • Python • Scala • and more. GraphQLとはRESTの代替としての立ち位置のクエリ言語です。
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- 7. Multiple requests inREST Endpoints /users /books /companies . . . I want resources at “/users” and “/books” and “/companies” REST server client database Users Books Companies RESTでは複数リソースを取得するために複数のリクエストが 必要となります。
- 8. Multiple requests inREST Resources Users Books Companies /users /books /companies Endpoints 複数のリソースに対して複数のエンドポイントが紐付いていま す。 REST
- 9. REST requires nrequests to retrieve n different resources. So if website required 100 different resources…? RESTでは大量のリクエストが発生する可能性がある。
- 10. Single request inGraphQL Endpoint /graphql I want resources at “/users” and “/books” and “/companies” GraphQL server client database Users Books Companies GraphQLでは単一のリクエストのみで複数のリソースが取得で きます。
- 11. Single request inGraphQL Resources Users Books Companies /graphql Endpoint “query” : “{ user book company }” Request Body なので、1つのエンドポイントに複数のリソースが紐付いてい る状態です。 GraphQL
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- 13. GraphQL library forScala Sangria ● The most famous Scala GraphQL library ● Github Repo ○ https://github.com/sangria-graphql/sangria ● There is an awesome documentation ○ http://sangria-graphql.org/ Scalaで実装されたGraphQLライブラリ「Sangria」
- 14. In my example,I prepared dummy data. These resources are same as a previous example; users, books, and companies In general, DummyData would be a database or data source. DummyData.scala 今回の例では、ダミーデータを使用した例で説明します。
- 15. In DummyDataRepo class, Idefined 3 methods to retrieve each resource. DummyRepo.scala ダミーデータを取得するレポジトリクラスを定義します。
- 16. GraphQLの根幹となる、オブジェクト構造を定義したクラスの 例です。 This is SchemaDefinition object,which defines Single Endpoint, Arguments, and Object Structures. In GraphQL, we have to define Object Structures to map onto query AST of request body. SchemaDefinition.scala
- 17. When you retrieveresources from this API, you need to access in HTTP Post method. In this example, I requests user data with id = 1, and the right side JSON shows response. GraphQLクエリでAPIリクエストした場合の例です。
- 18. Please look atmy sample code on Github for more detail. https://github.com/yuki-katada/scalamatsuri_sangria 詳細はGithubを参照してください。
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- 20. Pros • Less HTTPrequests (less API access) compared to REST • Additional server side implementation is not required in many cases – Only client side modification to GraphQL query is required • GraphiQL makes tests/debugs easier – An interactive in-browser IDE for GraphQL 長所
- 21. Cons • It isvery hard to design Domain-Specific architecture • Client Side is required to write very long request body – Who wants to write string formatted & type-unsafe request body…? • Many people struggle with GraphQL query – It is hard to understand for many people 短所
- 22. Result Cons are toocritical compared to pros… So we decided to replace GraphQL with REST :( 結果
- 23. Thank you forlistening :)