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The goal of this project is to exploreGraphQL. For it, we will implement twoSpring Boot Web Java applications:author-book-api andbook-review-api.

Note: Inkubernetes-minikube-environment repository, it's shown how to deploy this project inKubernetes (Minikube).

Onivangfr.github.io, I have compiled my Proof-of-Concepts (PoCs) and articles. You can easily search for the technology you are interested in by using the filter. Who knows, perhaps I have already implemented a PoC or written an article about what you are looking for.

• [Medium]Implementing and Securing a Spring Boot GraphQL API with Keycloak
• [Medium]Implementing and Securing a Spring Boot GraphQL API with Okta

• author-book-api

  Spring Boot Web Java application that handlesauthors andbooks. It exposes aGraphQL endpointand traditional REST API endpoints.author-book-api usesMySQL as storage and callsbook-review-api to get the reviews of the books. It usesFeign to easily create a client forbook-review-api andResilience4j (fault tolerance library) to handle fallback whenbook-review-api is down. The bookISBN is what connects books stored inauthor-book-api with the ones stored inbook-review-api.

• book-review-api

  Spring Boot Web Java application that handlesbooks and theirreviews. It only exposes aGraphQL API and usesMongoDB as storage.

In the repositoryreact-graphql-databases, I have implemented twoReactJS applicationsauthor-book-ui andbook-review-ui that are frontend applications forauthor-book-api andbook-review-api, respectively.

If you want to see the complete communication frontend-backend usingGraphQL, clone thereact-graphql-databases and follow the README instructions.

• Java 21+
• Some containerization toolDocker,Podman, etc.

• Open a terminal and insidespringboot-graphql-databases root folder run:

  docker compose up -d

• Wait for Docker containers to be up and running. To check it, run:

  docker ps -a

Insidespringboot-graphql-databases, run the following Maven commands in different terminals:

• author-book-api

  ./mvnw clean spring-boot:run --projects author-book-api \-Dspring-boot.run.jvmArguments="-Dspring.datasource.username=authorbookuser -Dspring.datasource.password=authorbookpass"

• book-review-api

  ./mvnw clean spring-boot:run --projects book-review-api \-Dspring-boot.run.jvmArguments="-Dspring.data.mongodb.username=bookreviewuser -Dspring.data.mongodb.password=bookreviewpass"

In a terminal and insidespringboot-graphql-databases root folder, run the following script:

./build-docker-images.sh

• author-book-api

  Environment Variable	Description
  MYSQL_HOST	Specify host of theMySQL database to use (defaultlocalhost)
  MYSQL_PORT	Specify port of theMySQL database to use (default3306)
  ZIPKIN_HOST	Specify host of theZipkin distributed tracing system to use (defaultlocalhost)
  ZIPKIN_PORT	Specify port of theZipkin distributed tracing system to use (default9411)
  BOOK_REVIEW_API_HOST	Specify host of thebook-review-api service (defaultlocalhost)
  BOOK_REVIEW_API_PORT	Specify port of thebook-review-api service (default9080)

• book-review-api

  Environment Variable	Description
  MONGODB_HOST	Specify host of theMongoDB database to use (defaultlocalhost)
  MONGODB_PORT	Specify port of theMongoDB database to use (default27017)
  ZIPKIN_HOST	Specify host of theZipkin distributed tracing system to use (defaultlocalhost)
  ZIPKIN_PORT	Specify port of theZipkin distributed tracing system to use (default9411)

In a terminal and insidespringboot-graphql-databases root folder, run following script:

./start-apps.sh

• book-review-api

  1. In a browser, accesshttp://localhost:9080/graphiql

  2. Create a book and return its id:

     mutation {  createBook(bookInput: {title: "Getting Started With Roo", isbn: "9781449307905"}) {   id  }}

  3. Add one review for the book created above, suppose the id is5bd4bd4790e9f641b7388f23:

     mutation {  addBookReview(bookId: "5bd4bd4790e9f641b7388f23", reviewInput: {reviewer: "Ivan Franchin", comment: "It is a very good book", rating: 5}) {    id  }}

  4. Get all books stored inbook-review-api, including their reviews:

     {  getBooks {    id    title    isbn    reviews {      comment      rating      reviewer      createdAt    }  }}

• author-book-api

  1. In a browser, accesshttp://localhost:8080/graphiql

  2. Create an author and return the author id:

     mutation {  createAuthor(authorInput: {name: "Josh Long"}) {    id  }}

  3. Create a book and return the book id and author name:

     Note: while creating this book inauthor-book-api, we are setting the same ISBN,9781449307905, as we did when creating the book inbook-review-api.

     mutation {  createBook(bookInput: {authorId: 1, isbn: "9781449307905", title: "Getting Started With Roo", year: 2020}) {    id    author {      name    }  }}

  4. Get author by id and return some information about his/her books including book reviews frombook-review-api:

     Note: as the book stored inauthor-book-api andbook-review-api has the same ISBN,9781449307905, it's possible to retrieve the reviews of the book. Otherwise, an empty list will be returned in casebook-review-api does not have a specific ISBN or the service is down.

     {  getAuthorById(authorId: 1) {    name    books {      isbn      title      bookReview {        reviews {          reviewer          rating          comment          createdAt        }      }    }  }}

  5. Update book title and return its id and new title:

     mutation {  updateBook(bookId: 1, bookInput: {title: "Getting Started With Roo 2"}) {    id    title  }}

  6. Delete the author and return author id:

     mutation {  deleteAuthor(authorId: 1) {    id  }}

• Zipkin

  It can be accessed athttp://localhost:9411

• MySQL monitor

  docker exec -it -e MYSQL_PWD=authorbookpass mysql mysql -uauthorbookuser --database authorbookdbSHOW tables;SELECT * FROM authors;SELECT * FROM books;

  Typeexit to get out of MySQL monitor

• MongoDB shell

  docker exec -it mongodb mongosh -u bookreviewuser -p bookreviewpass --authenticationDatabase bookreviewdbuse bookreviewdb;db.books.find().pretty();

  Typeexit to get out of MongoDB shell

• To stop applications:
  • If they were started withMaven, go to the terminals where they are running and pressCtrl+C;
  • If they were started as a Docker container, go to a terminal and, insidespringboot-graphql-databases root folder, run the script below:

    ./stop-apps.sh

• To stop and remove docker compose containers, network and volumes, go to a terminal and, insidespringboot-graphql-databases root folder, run the following command:

  docker compose down -v

To remove the Docker images created by this project, go to a terminal and, insidespringboot-graphql-databases root folder, run the following script:

./remove-docker-images.sh

• https://graphql.org/learn
• https://www.pluralsight.com/resources/blog/guides/building-a-graphql-server-with-spring-boot
• https://www.baeldung.com/spring-graphql