smallrye#521: initial GraphQL Federation extension

t1 · May 27, 2021 · 3aeb34d · 3aeb34d
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diff --git a/server/federation/README.adoc b/server/federation/README.adoc
@@ -0,0 +1,43 @@
+= GraphQL Federation
+
+Extension library to add support for https://www.apollographql.com/docs/federation/federation-spec/[GraphQL Federation].
+
+The `api` module defines the directives `@Key`, etc. The `runtime` module hooks into the SmallRye GraphQL events to dynamically enhance the GraphQL schema with the Federation extras (`_Entity`, `_Service`, etc.).
+
+== API
+
+Annotate the type you want to extend with `@Key`, e.g.:
+
+[source,java]
+----------
+@Key(fields = "id")
+public class Film {
+    String id;
+    String year;
+    String name;
+    // ...
+}
+----------
+
+In the service that extends that type, declare a reduced view that only defines the keys, e.g. `id`. Annotate the type as `@Extends` and the field as `@External`, e.g.:
+
+[source,java]
+----------
+@Extends @Key(fields = "id")
+public class Film {
+    @External String id;
+}
+----------
+
+And write a resolver method that adds the fields to that type, just like a 'local' `@Source` resolver would, but use `@FederatedSource` instead, e.g.:
+
+[source,java]
+----------
+class Reviews {
+    public List<Review> reviews(@FederatedSource Film film) {
+        //...
+    }
+}
+----------
+
+For a full example, see https://github.com/t1/graphql-federation-demo
diff --git a/server/federation/api/pom.xml b/server/federation/api/pom.xml
@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+         <groupId>io.smallrye</groupId>
+        <artifactId>smallrye-graphql-federation-parent</artifactId>
+        <version>1.2.3-SNAPSHOT</version>
+        <relativePath>../pom.xml</relativePath>
+    </parent>
+
+    <artifactId>smallrye-graphql-federation-api</artifactId>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.eclipse.microprofile.graphql</groupId>
+            <artifactId>microprofile-graphql-api</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.smallrye</groupId>
+            <artifactId>smallrye-graphql-api</artifactId>
+            <scope>provided</scope>
+        </dependency>
+    </dependencies>
+</project>
diff --git a/server/federation/api/src/main/java/io/smallrye/graphql/federation/api/Extends.java b/server/federation/api/src/main/java/io/smallrye/graphql/federation/api/Extends.java
@@ -0,0 +1,19 @@
+package io.smallrye.graphql.federation.api;
+
+import static io.smallrye.graphql.api.DirectiveLocation.INTERFACE;
+import static io.smallrye.graphql.api.DirectiveLocation.OBJECT;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Retention;
+
+import org.eclipse.microprofile.graphql.Description;
+
+import io.smallrye.graphql.api.Directive;
+
+/** <b><code>directive @extends on OBJECT | INTERFACE</code></b> */
+@Directive(on = { OBJECT, INTERFACE })
+@Description("Some libraries such as graphql-java don't have native support for type extensions in their printer. " +
+        "Apollo Federation supports using an @extends directive in place of extend type to annotate type references.")
+@Retention(RUNTIME)
+public @interface Extends {
+}
diff --git a/server/federation/api/src/main/java/io/smallrye/graphql/federation/api/External.java b/server/federation/api/src/main/java/io/smallrye/graphql/federation/api/External.java
@@ -0,0 +1,18 @@
+package io.smallrye.graphql.federation.api;
+
+import static io.smallrye.graphql.api.DirectiveLocation.FIELD_DEFINITION;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Retention;
+
+import org.eclipse.microprofile.graphql.Description;
+
+import io.smallrye.graphql.api.Directive;
+
+/** <b><code>directive @external on FIELD_DEFINITION</code></b> */
+@Directive(on = FIELD_DEFINITION)
+@Description("The @external directive is used to mark a field as owned by another service. " +
+        "This allows service A to use fields from service B while also knowing at runtime the types of that field.")
+@Retention(RUNTIME)
+public @interface External {
+}
diff --git a/server/federation/api/src/main/java/io/smallrye/graphql/federation/api/FederatedSource.java b/server/federation/api/src/main/java/io/smallrye/graphql/federation/api/FederatedSource.java
@@ -0,0 +1,19 @@
+package io.smallrye.graphql.federation.api;
+
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * A federated resolver method is the federated equivalent to a 'local' resolver method (with a parameter annotated as
+ * <code>{@link org.eclipse.microprofile.graphql.Source @Source}</code>), i.e. it adds a field with the name of the method
+ * and the type of the method return type to the source object.
+ * The class of the source parameter must be annotated as <code>{@link Extends @Extends}</code>
+ * and have at least one field annotated as <code>{@link External @External}</code>.
+ */
+@Retention(RUNTIME)
+@Target(PARAMETER)
+public @interface FederatedSource {
+}
diff --git a/server/federation/api/src/main/java/io/smallrye/graphql/federation/api/Key.java b/server/federation/api/src/main/java/io/smallrye/graphql/federation/api/Key.java
@@ -0,0 +1,22 @@
+package io.smallrye.graphql.federation.api;
+
+import static io.smallrye.graphql.api.DirectiveLocation.INTERFACE;
+import static io.smallrye.graphql.api.DirectiveLocation.OBJECT;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Retention;
+
+import org.eclipse.microprofile.graphql.Description;
+import org.eclipse.microprofile.graphql.NonNull;
+
+import io.smallrye.graphql.api.Directive;
+
+/** <b><code>directive @key(fields: _FieldSet!) on OBJECT | INTERFACE</code></b> */
+@Directive(on = { OBJECT, INTERFACE })
+@Description("The @key directive is used to indicate a combination of fields that can be used to uniquely identify " +
+        "and fetch an object or interface.")
+@Retention(RUNTIME)
+public @interface Key {
+    @NonNull
+    String[] fields();
+}
diff --git a/server/federation/api/src/main/java/io/smallrye/graphql/federation/api/Provides.java b/server/federation/api/src/main/java/io/smallrye/graphql/federation/api/Provides.java
@@ -0,0 +1,20 @@
+package io.smallrye.graphql.federation.api;
+
+import static io.smallrye.graphql.api.DirectiveLocation.FIELD_DEFINITION;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Retention;
+
+import org.eclipse.microprofile.graphql.Description;
+import org.eclipse.microprofile.graphql.NonNull;
+
+import io.smallrye.graphql.api.Directive;
+
+/** <b><code>directive @provides(fields: _FieldSet!) on FIELD_DEFINITION</code></b> */
+@Directive(on = FIELD_DEFINITION)
+@Description("When resolving the annotated field, this service can provide additional, normally `@external` fields.")
+@Retention(RUNTIME)
+public @interface Provides {
+    @NonNull
+    String[] fields();
+}
diff --git a/server/federation/api/src/main/java/io/smallrye/graphql/federation/api/Requires.java b/server/federation/api/src/main/java/io/smallrye/graphql/federation/api/Requires.java
@@ -0,0 +1,21 @@
+package io.smallrye.graphql.federation.api;
+
+import static io.smallrye.graphql.api.DirectiveLocation.FIELD_DEFINITION;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Retention;
+
+import org.eclipse.microprofile.graphql.Description;
+import org.eclipse.microprofile.graphql.NonNull;
+
+import io.smallrye.graphql.api.Directive;
+
+/** <b><code>directive @requires(fields: _FieldSet!) on FIELD_DEFINITION</code></b> */
+@Directive(on = FIELD_DEFINITION)
+@Description("In order to resolve the annotated field, this service needs these additional `@external` fields, " +
+        "even when the client didn't request them.")
+@Retention(RUNTIME)
+public @interface Requires {
+    @NonNull
+    String[] fields();
+}
diff --git a/server/federation/pom.xml b/server/federation/pom.xml
@@ -0,0 +1,39 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>io.smallrye</groupId>
+        <artifactId>smallrye-graphql-server-parent</artifactId>
+        <version>1.2.3-SNAPSHOT</version>
+        <relativePath>../pom.xml</relativePath>
+    </parent>
+
+    <artifactId>smallrye-graphql-federation-parent</artifactId>
+    <packaging>pom</packaging>
+
+    <modules>
+        <module>api</module>
+        <module>runtime</module>
+    </modules>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-source-plugin</artifactId>
+                <version>3.2.1</version>
+                <executions>
+                    <execution>
+                        <id>attach-sources</id>
+                        <goals>
+                            <goal>jar-no-fork</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+</project>
diff --git a/server/federation/runtime/pom.xml b/server/federation/runtime/pom.xml
@@ -0,0 +1,44 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+         <groupId>io.smallrye</groupId>
+        <artifactId>smallrye-graphql-federation-parent</artifactId>
+        <version>1.2.3-SNAPSHOT</version>
+        <relativePath>../pom.xml</relativePath>
+    </parent>
+
+    <artifactId>smallrye-graphql-federation-runtime</artifactId>
+
+    <dependencies>
+        <dependency>
+             <groupId>io.smallrye</groupId>
+            <artifactId>smallrye-graphql-federation-api</artifactId>
+            <version>${project.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>jakarta.enterprise</groupId>
+            <artifactId>jakarta.enterprise.cdi-api</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.smallrye</groupId>
+            <artifactId>smallrye-graphql</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.smallrye</groupId>
+            <artifactId>smallrye-graphql-schema-builder</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.jboss.logging</groupId>
+            <artifactId>jboss-logging</artifactId>
+            <scope>provided</scope>
+        </dependency>
+    </dependencies>
+</project>