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Beyond REST: Coursera’s Journey to GraphQL
Bryan Kane ! @bryanskane " bryan-coursera
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
4
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
5
Load Courses
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
6
Load Instructors
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
7
Load Universities
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
Load University Profile
8
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
9
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
10
Backend Client
APIs
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
11
Discussion
AssetService Emails
Catalog Courservice
LearningHierarchy Recs
Growth
Enterprise
Payment
TranslationsLearning
Items UsersAuthEventing
Backend Client
Discussion
AssetService
Emails
Catalog Courservice
LearningHierarchy
Recs
Growth
Enterprise
Payment
Translations LearningItems
UsersAuthEventing
APIs
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
12
Discu
Asset Email
Catal Cours
Learn Recs
Grow
Enter
Paym
Transl Learn UsersAuthEvent
APIs
Backend Client
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
Catalog
13
partners.v1 instructors.v1
courseGrades.v1
courses.v1
enrollments.v1
enrollments.v2
courseVideos.v1quizzes.v1
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
Catalog
14
partners.v1 instructors.v1
courseGrades.v1
courses.v1
enrollments.v1
enrollments.v2
courseVideos.v1quizzes.v1
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
Catalog
15
partners.v1 instructors.v1
courseGrades.v1
courses.v1
enrollments.v1
enrollments.v2
courseVideos.v1quizzes.v1
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
Catalog
16
partners.v1 instructors.v1
courseGrades.v1
courses.v1
enrollments.v1
enrollments.v2
courseVideos.v1quizzes.v1
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
17
Discussion
AssetService
Emails
Catalog Courservice
LearningHierarchy
Recs
Growth
Enterprise
Payment
Translations LearningItems
UsersAuthEventing
Discu
Asset Email
Catal Cours
Learn Recs
Grow
Enter
Paym
Transl Learn UsersAuthEvent
APIs
Backend Client
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
18
We didn’t break up the monolith —
we just moved it to the clients.
Chapter One Site speed
issues
Chapter Two Intro to GraphQL
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
19
Chapter One Site speed
issues
Chapter Two Intro to GraphQL
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
20
GraphQL is a
query language,
not a library.
Chapter One Site speed
issues
Chapter Two Intro to GraphQL
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
21
query MyCoursesQuery { myCourses(limit: 5, sortBy: RECENT) { name slug instructors { firstName lastName university(filter: VISIBLE_TO_LEARNERS) { name country slug } } } }
Chapter One Site speed
issues
Chapter Two Intro to GraphQL
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
query MyCoursesQuery { myCourses(limit: 5, sortBy: RECENT) { name slug instructors { firstName lastName university(filter: VISIBLE_TO_LEARNERS) { name country slug } } } }
22
Chapter One Site speed
issues
Chapter Two Intro to GraphQL
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
query MyCoursesQuery { myCourses(limit: 5, sortBy: RECENT) { name slug instructors { firstName lastName university(filter: VISIBLE_TO_LEARNERS) { name country slug } } } }
23
Chapter One Site speed
issues
Chapter Two Intro to GraphQL
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
query MyCoursesQuery { myCourses(limit: 5, sortBy: RECENT) { name slug instructors { firstName lastName university(filter: VISIBLE_TO_LEARNERS) { name country slug } } } }
24
Chapter One Site speed
issues
Chapter Two Intro to GraphQL
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
25
query MyCoursesQuery { myCourses(limit: 5, sortBy: RECENT) { name slug instructors { firstName lastName university(filter: VISIBLE_TO_LEARNERS) { name country slug } } } }
Chapter One Site speed
issues
Chapter Two Intro to GraphQL
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
26
{ "myCourses": [ { "name": "Machine Learning", "slug": "machine-learning", "instructors": [ { "firstName": "Andrew", "lastName": "Ng" "university": { "name": "Stanford University", "country": "United States", "slug": "stanford" } }] }] }
Chapter One Site speed
issues
Chapter Two Intro to GraphQL
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
27
query MyCoursesQuery { myCourses(limit: 5, sortBy: RECENT) { name slug instructors { firstName lastName university(filter: VISIBLE_TO_LEARNERS) { name country slug } } } }
{ "myCourses": [{ "name": "Machine Learning", "slug": "machine-learning", "instructors": [{ "firstName": "Andrew", "lastName": "Ng" "university": { "name": "Stanford University", "country": "United States", “slug": "stanford" } }] }] }
Chapter One Site speed
issues
Chapter Two Intro to GraphQL
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
28
Chapter One Site speed
issues
Chapter Two Intro to GraphQL
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
29
query CoursePage { course(slug: "machine-learning") { title description } }
<Course />
Chapter One Site speed
issues
Chapter Two Intro to GraphQL
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
30
query CoursePage { course(slug: "machine-learning") { title description
} }
<Course />
university { name logo }
<University />
Chapter One Site speed
issues
Chapter Two Intro to GraphQL
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
31
query CoursePage { course(slug: "machine-learning") { title description
} }
<Course />
university { name logo }
<University />
instructor { name title }
<Instructor />
Chapter One Site speed
issues
Chapter Two Intro to GraphQL
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
32
query CoursePage { course(slug: machine-learning") { title description
} }
<Course />
university { name logo }
<University />
instructor { name title
}
<Instructor />
profile { photo }
<ProfilePhoto />
Chapter One Site speed
issues
Chapter Two Intro to GraphQL
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
33
All queries are backedby a typed schema
Chapter One Site speed
issues
Chapter Two Intro to GraphQL
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
34
type root { myCourses(limit: Int, sortBy: COURSE_SORT): [Course] }
enum COURSE_SORT { RECENT ENROLL_DATE }
type Course { name: String slug: String instructors: [Instructor] }
type Instructor { firstName: String lastName: String university(filter: VISIBILITY_FILTER): University }
Chapter One Site speed
issues
Chapter Two Intro to GraphQL
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
35
Chapter One Site speed
issues
Chapter Two Intro to GraphQL
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
36
Small, but rapidly growing community
Chapter One Site speed
issues
Chapter Two Intro to GraphQL
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
37
visit graphql.org
for more info
38
Migrating to GraphQL
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
39
Backend
Discussion
AssetService
Emails
Catalog Courservice
LearningHierarchy
Recs
Growth
Enterprise
Payment
Translations LearningItems
UsersAuthEventing
Disc
Jon Em
Cat Cou
Lea Rec
Gro
Ent
Pay
Tra Lea UseAutEve
Client
Discussion
AssetService
Emails
Catalog Courservice
LearningHierarchy
Recs
Growth
Enterprise
Payment
Translations LearningItems
UsersAuthEventing
Disc
Ass Em
Cat Cou
Lea Rec
Gro
Ent
Pay
Tra Lea UseAutEve
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
40
Codebase consistency
Convert REST to GraphQL
Add GraphQL on top of REST
Multiple API formatsOne API format
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
41
Codebase consistency
Convert REST to GraphQL
Add GraphQL on top of REST
Multiple API formatsOne API format
Higher investment Lower investmentTime investment
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
42
Codebase consistency
Convert REST to GraphQL
Add GraphQL on top of REST
Multiple API formatsOne API format
Higher investment Lower investment
More flexible Less flexible
Time investment
Full power of GraphQL
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
43
Codebase consistency
Convert REST to GraphQL
Add GraphQL on top of REST
Multiple API formatsOne API format
Higher investment Lower investment
More flexible Less flexible
Less coordination required
More coordination required
Time investment
Full power of GraphQL
Rollout strategy
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
44
Codebase consistency
Convert REST to GraphQL
Add GraphQL on top of REST
Multiple API formatsOne API format
Higher investment Lower investment
More flexible Less flexible
Less coordination required
More coordination required
Greater schema consistency
Can lead to arbitrary schema formats
Time investment
Full power of GraphQL
Rollout strategy
Schema consistency
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
45
Codebase consistency
Convert REST to GraphQL
Add GraphQL on top of REST
Multiple API formatsOne API format
Higher investment Lower investment
More flexible Less flexible
Less coordination required
More coordination required
Greater schema consistency
Can lead to arbitrary schema formats
Time investment
Full power of GraphQL
Rollout strategy
Schema consistency
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
46
Discuss
Asset Emails
Catalog Course
Learnin Recs
Growth
Enterpr
Payme
Transla Learnin UsersAuthEventin
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
47
Discuss
Asset Emails
Catalog Course
Learnin Recs
Growth
Enterpr
Payme
Transla Learnin UsersAuthEventin
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
CataloCatalog
48
Discuss
Asset Emails
Course
Learnin Recs
Growth
Enterpr
Payme
Transla Learnin UsersAuthEventin
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
CataloCatalog
49
Discuss
Asset Emails
Course
Learnin Recs
Growth
Enterpr
Payme
Transla Learnin UsersAuthEventin
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
1
List of public APIs
2
Endpoints and arguments
3
Model schemas
50
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
51
Discussion
AssetService
Emails
Catalog Courservice
LearningHierarchy
Recs
Growth
Enterprise
Payment
TranslationsLearning
ItemsUsersAuthEventing
Assembler
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
52
Schema Designtype CoursesV1 { id: String slug: String ...more fields }
type CoursesV1Resource { myWatchlist(limit: Int, start: String): CoursesV1Connection bySlug(slug: String, limit: Int, start: String): CoursesV1Connection getAll(limit: Int, start: String): CoursesV1Connection get(id: String!): CoursesV1 multiGet(ids: [String], limit: Int, start: String): CoursesV1Connection }
type CoursesV1Connection { elements: [CoursesV1] paging: ResponsePagination }
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
53
https://www.coursera.org /api/courses.v1 ?q=bySlug &slug=ml &fields=id,name,courseUrl
query CoursePageQuery { CoursesV1Resource { bySlug(slug: "ml") { id name courseUrl } } }
REST to GraphQL
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
54
query CoursePageQuery { CoursesV1Resource { course(limit: 123) { instructor { name university { slug country } } myEnrollments { grade } } } }
Data Relations are Powerful
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
55
Backend APIs are a black box
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
56
Backend APIs are a black box• Joining across APIs is hard
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
57
Backend APIs are a black box• Joining across APIs is hard
• We don’t use relational databases • Most data is stored in Cassandra, a NoSQL database • This requires explicit indexes on data for lookups
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
58
Backend APIs are a black box• Joining across APIs is hard
• We don’t use relational databases • Most data is stored in Cassandra, a NoSQL database • This requires explicit indexes on data for lookups
• We want to keep services as independent as possible
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
59
Two types of relationships
Course Instructor
model Course { id slug instructorIds }
model Instructor { id name }
model A knows about model B
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
60
Course Enrollment
model Course { id slug }
model Enrollment { id userId courseId }
Two types of relationships
model A doesn’t know about model B model B knows about model A
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
These are easy — just fetch the data you need by ID
61
courseAPI.addRelation( "instructors" -> ForwardRelation( resourceName = "instructors.v1", idField = "instructorIds", arguments = Map("includeHidden" -> "true"))
Forward Relationships
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
• Define an endpoint on resource B to lookup by model A • Define in resource A how to look up on resource B
62
courseAPI.addRelation( "enrollment" -> ReverseRelation( resourceName = "enrollments.v1", finderName = "byCourseAndUser", arguments = Map( "courseId" -> "$id", "version" -> "$version"))
Reverse Relationships
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
63
Imperative
courseAPI.addRelation({ course => instructorClient.fetchByCourseId(course.id, course.version) .onComplete { instructors => course.set("instructors", instructors) }.onFailure { course.set("instructors", List.empty) } })
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Four Learnings and retrospective
Chapter Two Intro to GraphQL
64
Imperative
courseAPI.addRelation({ course => instructorClient.fetchByCourseId(course.id, course.version) .onComplete { instructors => course.set("instructors", instructors) }.onFailure { course.set("instructors", List.empty) } })
courseAPI.addRelation( "instructors" -> ReverseRelation( resourceName = "instructors.v1", finderName = "byCourseId", arguments = Map("courseId" -> "$id", "version" -> "$version"))
Declarative
Chapter Four Learnings and retrospective
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Two Intro to GraphQL
65
Chapter Four Learnings and retrospective
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Two Intro to GraphQL
query { CoursesV1Resource { bySlug(slug: "machine-learning") { coursePurchases { transactions { transactionDate expirationDate } } certificates { certificateGrantDate certificateGrade } } offersCertificateForPurchase } EnterpriseProgramsV1Resource { myPrograms { eligibleCourses } } } 66
Actual Query Ideal Query
Chapter Four Learnings and retrospective
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Two Intro to GraphQL
query { CoursesV1Resource { bySlug(slug: "machine-learning") { coursePurchases { transactions { transactionDate expirationDate } } certificates { certificateGrantDate certificateGrade } } offersCertificateForPurchase } EnterpriseProgramsV1Resource { myPrograms { eligibleCourses } } } 67
Actual Query Ideal Query
Chapter Four Learnings and retrospective
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Two Intro to GraphQL
query { CoursesV1Resource { bySlug(slug: "machine-learning") { coursePurchases { transactions { transactionDate expirationDate } } certificates { certificateGrantDate certificateGrade } } offersCertificateForPurchase } EnterpriseProgramsV1Resource { myPrograms { eligibleCourses } } } 68
query { CoursesV1Resource { bySlug(slug: "machine-learning") { shouldShowUpsell } } }
Actual Query Ideal Query
Chapter Four Learnings and retrospective
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Two Intro to GraphQL
69
GraphQL isn't magic
Chapter Four Learnings and retrospective
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Two Intro to GraphQL
70
GraphQL isn't magic
• Don’t let your GraphQL queries become too complex —
move your business logic downstream.
Chapter Four Learnings and retrospective
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Two Intro to GraphQL
71
GraphQL isn't magic
• Don’t let your GraphQL queries become too complex —
move your business logic downstream.
• Build your APIs with GraphQL in mind —
don’t let them live in a silo.
Chapter Four Learnings and retrospective
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Two Intro to GraphQL
72
Popular Courses for JournalistsLearn what it takes to report the news, conduct historical research,understand different viewpoints, and even produce your own intro music.
Chapter Four Learnings and retrospective
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Two Intro to GraphQL
73
Popular Courses for JournalistsLearn what it takes to report the news, conduct historical research,understand different viewpoints, and even produce your own intro music.
query CourseCollectionQuery(slug: String!) { CourseCollectionV1Resource { bySlug(slug: $slug) { title subtitle entries { isEnrolled isOnWishlist course { name photo } } } } }
Chapter Four Learnings and retrospective
Chapter One Site speed
issues
Chapter Three Migrating to
GraphQL
Chapter Two Intro to GraphQL
74
Popular Courses for JournalistsLearn what it takes to report the news, conduct historical research,understand different viewpoints, and even produce your own intro music.
Thanks!Bryan Kane
! @bryanskane " bryan-coursera
