feat: Support for Slash GraphqQL endpoint (#158)

antblood · abhimanyusinghgaur · web-flow · commit b7dce2af40f9 · 2020-10-23T16:36:13.000+05:30
This PR adds a method on DgraphClient to easily construct a gRPC stub for Slash GraphQL endpoints.

Co-authored-by: Abhimanyu Singh Gaur &lt;12651351+abhimanyusinghgaur@users.noreply.github.com&gt;
diff --git a/README.md b/README.md
@@ -25,6 +25,7 @@ and understand how to run and work with Dgraph.
 - [Intro](#intro)
 - [Using the Synchronous Client](#using-the-synchronous-client)
   * [Creating a Client](#creating-a-client)
+  * [Creating a Client for Slash Graphql Endpoint](#creating-a-client-for-slash-graphql-endpoint)
   * [Creating a Secure Client Using TLS](#creating-a-secure-client-using-tls)
   * [Check Dgraph Version](#check-dgraph-version)
   * [Login Using ACL](#login-using-acl)
@@ -154,6 +155,15 @@ DgraphStub stub3 = DgraphGrpc.newStub(channel3);
 DgraphClient dgraphClient = new DgraphClient(stub1, stub2, stub3);
 ```
 
+### Creating a Client for Slash Graphql Endpoint
+
+If you want to connect to Dgraph running on your [Slash GraphQL](https://slash.dgraph.io) instance, then all you need is the URL of your Slash GraphQL endpoint and the API key. You can get a client using them as follows :
+
+```java
+DgraphStub stub = DgraphClient.clientStubFromSlashEndpoint("https://your-slash-instance.cloud.dgraph.io/graphql", "your-api-key");
+DgraphClient dgraphClient = new DgraphClient(stub);
+```
+
 ### Creating a Secure Client using TLS
 
 To setup a client using TLS, you could use the following code snippet. The server needs to be
diff --git a/src/main/java/io/dgraph/DgraphClient.java b/src/main/java/io/dgraph/DgraphClient.java
@@ -19,6 +19,13 @@
 import io.dgraph.DgraphProto.TxnContext;
 import io.dgraph.DgraphProto.Version;
 
+import io.grpc.ManagedChannelBuilder;
+import io.grpc.Metadata;
+import io.grpc.stub.MetadataUtils;
+
+import java.net.MalformedURLException;
+import java.net.URL;
+
 /**
  * Implementation of a DgraphClient using grpc.
  *
@@ -27,18 +34,46 @@
  * @author Edgar Rodriguez-Diaz
  * @author Deepak Jois
  * @author Michail Klimenkov
+ * @author Neeraj Battan
+ * @author Abhimanyu Singh Gaur
  */
 public class DgraphClient {
+  private static final String gRPC_AUTHORIZATION_HEADER_NAME = "authorization";
 
   private final DgraphAsyncClient asyncClient;
 
+  /**
+   * Creates a gRPC stub that can be used to construct clients to connect with Slash GraphQL.
+   *
+   * @param slashEndpoint The url of the Slash GraphQL endpoint. Example:
+   *                      https://your-slash-instance.cloud.dgraph.io/graphql
+   * @param apiKey        The API key used to connect to your Slash GraphQL instance.
+   * @return A new DgraphGrpc.DgraphStub object to be used with DgraphClient/DgraphAsyncClient.
+   */
+  public static DgraphGrpc.DgraphStub clientStubFromSlashEndpoint(
+      String slashEndpoint, String apiKey) throws MalformedURLException {
+    String[] parts = new URL(slashEndpoint).getHost().split("[.]", 2);
+    if (parts.length < 2) {
+      throw new MalformedURLException("Invalid Slash URL.");
+    }
+    String gRPCAddress = parts[0] + ".grpc." + parts[1];
+
+    Metadata metadata = new Metadata();
+    metadata.put(Metadata.Key.of(gRPC_AUTHORIZATION_HEADER_NAME,
+        Metadata.ASCII_STRING_MARSHALLER), apiKey);
+    return MetadataUtils.attachHeaders(
+        DgraphGrpc.newStub(
+            ManagedChannelBuilder.forAddress(gRPCAddress, 443).useTransportSecurity().build()),
+        metadata);
+  }
+
   /**
    * Creates a new client for interacting with a Dgraph store.
    *
    * <p>A single client is thread safe.
    *
    * @param stubs - an array of grpc stubs to be used by this client. The stubs to be used are
-   *     chosen at random per transaction.
+   *              chosen at random per transaction.
    */
   public DgraphClient(DgraphGrpc.DgraphStub... stubs) {
     this.asyncClient = new DgraphAsyncClient(stubs);
@@ -142,7 +177,7 @@ public Version checkVersion() {
    * access JWT and a refresh JWT, which will be stored in the jwt field of this class, and used for
    * authorizing all subsequent requests sent to the server.
    *
-   * @param userid the id of the user who is trying to login, e.g. Alice
+   * @param userid   the id of the user who is trying to login, e.g. Alice
    * @param password the password of the user
    */
   public void login(String userid, String password) {
diff --git a/src/test/java/io/dgraph/DgraphClientTest.java b/src/test/java/io/dgraph/DgraphClientTest.java
@@ -15,21 +15,24 @@
  */
 package io.dgraph;
 
-import static org.testng.Assert.assertEquals;
-import static org.testng.Assert.assertTrue;
-
 import com.google.gson.JsonObject;
 import com.google.gson.JsonParser;
 import com.google.protobuf.ByteString;
 import io.dgraph.DgraphProto.Mutation;
 import io.dgraph.DgraphProto.Operation;
 import io.dgraph.DgraphProto.Response;
 import io.dgraph.DgraphProto.TxnContext;
+
+import java.net.MalformedURLException;
 import java.util.Collections;
 import java.util.Map;
+
 import org.testng.annotations.BeforeMethod;
 import org.testng.annotations.Test;
 
+import static org.testng.Assert.*;
+import static org.testng.Assert.fail;
+
 /**
  * @author Edgar Rodriguez-Diaz
  * @author Deepak Jois
@@ -150,4 +153,23 @@ public void testCheckVersion() {
     assertTrue(v.getTag().length() > 0);
     assertEquals(v.getTag().charAt(0), 'v');
   }
+
+  @Test
+  public void testFromSlashEndpoint_ValidURL() {
+    try {
+      DgraphClient.clientStubFromSlashEndpoint("https://your-slash-instance.cloud.dgraph" +
+          ".io/graphql", "");
+    } catch (MalformedURLException e) {
+      fail(e.getMessage());
+    }
+  }
+
+  @Test
+  public void testFromSlashEndpoint_InValidURL() {
+    try {
+      DgraphClient.clientStubFromSlashEndpoint("https://a-bad-url", "");
+      fail("Invalid Slash URL should not be accepted.");
+    } catch (MalformedURLException e) {
+    }
+  }
 }
