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= GraphQL Server Introduction
:description: Helidon GraphQL Server Introduction
:keywords: helidon, graphql, java
:feature-name: GraphQL
:rootdir: {docdir}/..
include::{rootdir}/includes/se.adoc[]
== Contents
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== Overview
The Helidon GraphQL Server provides a framework for creating link:https://github.com/graphql-java/graphql-java[GraphQL]
applications that integrate with the Helidon WebServer. GraphQL is a query language to access server data.
The Helidon GraphQL integration enables HTTP clients to issue queries over the network and retrieve data;
it is an alternative to other protocols such as REST or GRPC.
include::{rootdir}/includes/dependencies.adoc[]
[source,xml]
----
io.helidon.graphql
helidon-graphql-server
----
== API
An instance of `GraphQlSupport` must be registered in the Helidon WebServer routes to enable
GraphQL support in your application. In addition, a GraphQL schema needs to be specified
to verify and execute queries.
The following code fragment creates an instance of `GraphQlSupport` and registers it in the
Helidon WebServer.
[source,java]
----
include::{sourcedir}/se/GraphQlSnippets.java[tag=snippet_1, indent=0]
----
By default, `GraphQlSupport` will reserve `/graphql` as the URI path to process queries.
The `buildSchema` method creates the schema and defines 2 types of queries for this
application:
[source,java]
----
include::{sourcedir}/se/GraphQlSnippets.java[tag=snippet_2, indent=0]
----
The following is a description of each of these steps:
<1> Define the GraphQL schema.
<2> Create a `DataFetcher` to return a list of hellos in different languages.
<3> Wire up the `DataFetcher` s.
<4> Generate the GraphQL schema.
== Configuration
include::{rootdir}/includes/graphql.adoc[]
== Examples
Using the schema defined in Section <>, you can probe the following endpoints:
1. Hello world endpoint
+
[source,bash]
----
curl -X POST http://127.0.0.1:PORT/graphql -d '{"query":"query { hello }"}'
"data":{"hello":"world"}}
----
2. Hello in different languages
+
[source,bash]
----
curl -X POST http://127.0.0.1:PORT/graphql -d '{"query":"query { helloInDifferentLanguages }"}'
{"data":{"helloInDifferentLanguages":["Bonjour","Hola","Zdravstvuyte","Nǐn hǎo","Salve","Gudday","Konnichiwa","Guten Tag"]}}
----
== Additional Information
* link:{graphql-javadoc-base-url}/module-summary.html[GraphQL Javadocs]