Exploring GraphQL on Android with Apollo

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EXPLORING GRAPHQL WITH APOLLO Ubiratan Soares Agosto / 2017

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IS NOT

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WE MUST TALK ABOUT REST

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2000

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2000

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2017

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2017

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REST WAS NOT DESIGNED WITH NOWADAYS APPLICATIONS, DEVICES AND USERS IN MIND …

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Design Develop Measure API AS PRODUCT

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KNOW ISSUES FROM REST

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SCHEMA-LESS

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VERSIONING

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MULTIPLE ENDPOINTS TO SOLVE A SPECIFIC NEED FROM CLIENT

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ENDPOINT EXPOSES MORE DATA THAN CLIENT NEEDS PER HTTP REQUEST

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MAIN GOALS

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Single Endpoint “Goodbye" versioning headaches 1

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Well deﬁned contract Client and server must respect a schema for effective data exchange 2

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No more overfetching GraphQL clients can fetch only the data they really need for a given purpose 3

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4 No more underfetching GraphQL clients can retrieve all the data they need into a single HTTP call : no more chained and/or parallel HTTP requests

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CORE CONCEPTS

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TYPE SYSTEM AND SCHEMA

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Field name != Type name

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QUERY (IP) LOCDATA city : city location : location LOCATION latitude : String longitude : String time_zone : String CITY geoname_id : String names : cityNames ACCEPTS RETURNS . . . . . . CITYNAMES de : String en : String ru : String . . .

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QUERIES AND MUTATIONS

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{ getLocation(ip: “172.59.226.170") { country { names { en } geoname_id iso_code } location { latitude longitude } } } Operation Root Query parameter Data that actually matters

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{ getLocation(ip: “172.59.226.170") { country { names { en } geoname_id iso_code } location { latitude longitude } } } "For the available data, return the English name for the country"

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{ getLocation(ip: “172.59.226.170") { country { names { en } geoname_id iso_code } location { latitude longitude } } } "For the available data, return the latitude and the longitude from the geolocation info"

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{ "data": { "getLocation": { "country": { "names": { "en": "Brazil" }, "geoname_id": "3469034", "iso_code": "BR" }, "location": { "latitude": "-23.5733", "longitude": "-46.6417" } } } } QUERY

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MORE ABOUT OPERATIONS • Data payload will mirror the type hierarchy deﬁned on schema • All data types for queries/mutations must be deﬁned on schema • Operation can accept parameters and/or variables • We can form better, readable blocks for operations using aliases and fragments • Etc

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CLIENT INTENT REST + HTTP GraphQL + HTTP GraphQL Operation READ RESOURCE GET POST QUERY CREATE RESOURCE POST POST MUTATION UPDATE RESOURCE PUT POST MUTATION REMOVE RESOURCE DELETE POST MUTATION

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HOW TO USE ON ANDROID ?

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APOLLO + ANDROID • Full-featured tooling + library, inspired by Retroﬁt • Custom OkHttpClient support • Code generation for queries / mutations : request models and payloads • Cache-ready client, including L0, L1 e L2 support • RxJava support • Etc

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PREPARE YOUR QUERY OR MUTATION

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query LocationQuery ($ip: String!) { getLocation(ip: $ip) { country { names { en } geoname_id iso_code } location { latitude longitude } } } Generated class member To-be-generated class name Operation Type

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query LocationQuery($ip: String!) { getLocation(ip: $ip) { country { names { en } geoname_id iso_code } location { latitude longitude } } } queryname.graphql

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RETRIEVE THE ACTUAL SCHEMA

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> brew install npm

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> brew install npm > npm install -g apollo-codegen

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> apollo-codegen download-schema \ https://api.graphloc.com/graphql \ --output schema.json > brew install npm > npm install -g apollo-codegen

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PROJECT INTEGRATION

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APPLY PLUGIN AND DEPENDENCIES

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DEFINE YOUR WORK DIRECTORY

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Deﬁne the package for generated classes Convention DO NOT forget to put schema here

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class GraphQLAccess { private val apolloClient = ApolloClient .builder() .serverUrl("https://api.graphloc.com/graphql") .build() } // continue ... }

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fun fetchGeolocation(): Observable { val ipAddress = "8.8.8.8" val locationQuery = LocationQuery.builder() .ip(ipAddress) .build() val call = apolloClient.query(locationQuery) return Rx2Apollo .from(call) .map { data -> toGeolocationInfo(data, ipAddress) } }

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private fun toGeolocationInfo( dataResponse: Response, ipAddress: String): GeolocationInformation { val data = dataResponse.data()?.getLocation val location = data?.location return GeolocationInformation( ip = ipAddress, countryName = data?.country?.names?.en, cityName = data?.city?.names?.en, latitude = location?.latitude, longitutde = location?.longitude, timezone = location?.time_zone ) }

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DONE

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JUST ADD MORE QUERIES / MUTATIONS AND BE HAPPY !!!

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FINAL REMARKS

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FINAL REMARKS • GraphQL is just a spec

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FINAL REMARKS • GraphQL is just a spec • GraphQL aims to solve some of well know issues from REST

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FINAL REMARKS • GraphQL is just a spec • GraphQL aims to solve some of well know issues from REST • GraphQL is mobile friendly, but it brings its own set of challenges (for free, rs)

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FINAL REMARKS • GraphQL is just a spec • GraphQL aims to solve some of well know issues from REST • GraphQL is mobile friendly, but it brings its own set of challenges (for free, rs) • Apollo is an OSS effort for easy integration of GraphQL clients, and it has a full-featured Android native API

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REFERENCES Oﬁcial GraphQL Website http://graphql.org How to GraphQL https://www.howtographql.com Github Training on GraphQL https://services.github.com/on-demand/graphql Apollo Client for Android - Documentation http://dev.apollodata.com/android

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https://speakerdeck.com/ubiratansoares

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UBIRATAN SOARES Computer Scientist by ICMC/USP Software Engineer, curious guy Google Developer Expert for Android Teacher, speaker, etc, etc

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THANK YOU @ubiratanfsoares ubiratansoares.github.io https://br.linkedin.com/in/ubiratanfsoares