GraphQL

AppSync/GraphQL.md

@@ -0,0 +1,43 @@
+# GraphQL
+GraphQL is an FOSS agnostic query adaptor that allows you to query data from many different data sources. GraphQL is used to build APIs where clients will send a query for nested data. GraphQL mitigates the issue of versioned or rapidly changing APIs compared to REST APIs because you can request the data you want.
+
+GraphQL schemas are written in the GraphQL SDL (Schema Definition Language) composed on:
+- **Types**. Represent objects and their **fields**:
+```graphql
+type Query {
+    me: User
+}
+
+type User {
+    id: ID
+    name: String
+}
+```
+- **Fields**
+- **Queries**. Define the exact shape of the data needed by the client:
+```graphql
+query CurrentUser {
+    currentUser {
+        name
+        age
+    }
+}
+```
+- **Mutations**. Allow for data to be create, updated or deleted:
+```graphql
+mutation CreateUser($name: String!, $age: Int!) {
+    createUser(userName: $name, age: $age) {
+        name
+        age
+    }
+}
+```
+- **Subscriptions**. Supports live updates sent from the server to the client:
+```graphql
+subscription {
+    newPerson {
+        name
+        age
+    }
+}
+```