{"id":947,"date":"2022-06-03T11:35:00","date_gmt":"2022-06-03T09:35:00","guid":{"rendered":"https:\/\/nubisoft.io\/blog\/?p=947"},"modified":"2022-10-03T11:42:58","modified_gmt":"2022-10-03T09:42:58","slug":"how-to-start-with-graphql-in-java","status":"publish","type":"post","link":"https:\/\/nubisoft.io\/blog\/how-to-start-with-graphql-in-java\/","title":{"rendered":"How to start with GraphQL in Java"},"content":{"rendered":"\n

In this blog post, you will learn some basics about GraphQL<\/strong> and how to start using it in an actual project with Java<\/strong> language and Spring Boot<\/strong> technology.<\/p>\n\n\n\n

What is GraphQL?<\/h2>\n\n\n\n

GraphQL is a query language for APIs and a runtime for fulfilling those queries with your existing data. The main concept of GraphQL is strong typing which determines the way of communication between the client and server. GraphQL’s main feature is its flexibility, which can be determined on the basis of two phenomena that very often occurs when using REST architecture – data over and under-fetching. <\/p>\n\n\n\n

Data Under-Fetching is a phenomenon that occurs when there is fewer data in response than the requester needs. This situation forces the client or other microservice to shoot the server whit another request to get the missing data. <\/p>\n\n\n\n

Data Over-Fetching is a phenomenon that occurs when there is more data in response than the client or other microservice uses.<\/p>\n\n\n\n

In both cases, there are performance issues that cause problems. In the first case, the client is forced to make additional HTTP requests when it should send only a single request in the ideal situation. In the second case, there is more usage of bandwidth than it could be, as the client is not using all the data that was received, which also slows down the application. <\/p>\n\n\n\n

Against these problems, there is the GraphQL language, which thanks to the above-mentioned flexibility, i.e. the possibility of sending many queries within one request and the possibility of selecting the required fields within each request eliminates these two phenomena such as data under and over-fetching.<\/p>\n\n\n\n

Basics of GraphQL<\/h2>\n\n\n\n

In GraphQL to create an API, it is necessary to create schemas that will define possible queries including what this query will return and what are the required parameters. There are two main concepts for operating on the data: Queries<\/em> and Mutations<\/em>. <\/p>\n\n\n\n

Query<\/em> in GraphQL is a substitute for HTTP GET in REST architecture and it’s used only to get data from the server. <\/p>\n\n\n\n

Mutation<\/em> is a substitute for HTTP POST\/PUT\/DELETE which is used to operate on data especially by sending new data to the server, updating already existing data, or deleting it from the server.<\/p>\n\n\n\n

In each of the GraphQL operations, we have some keywords that allow defining schemas: <\/p>\n\n\n\n