Construct routing driver from first available address

driver/src/main/java/org/neo4j/driver/internal/DriverFactory.java

@@ -47,10 +47,12 @@
 
 import static java.lang.String.format;
 import static org.neo4j.driver.internal.security.SecurityPlan.insecure;
-import static org.neo4j.driver.v1.Config.EncryptionLevel.REQUIRED;
 
 public class DriverFactory
 {
+    public static final String BOLT_URI_SCHEME = "bolt";
+    public static final String BOLT_ROUTING_URI_SCHEME = "bolt+routing";
+
     public final Driver newInstance( URI uri, AuthToken authToken, RoutingSettings routingSettings,
             RetrySettings retrySettings, Config config )
     {
@@ -86,10 +88,10 @@ private Driver createDriver( URI uri, BoltServerAddress address, ConnectionPool
         String scheme = uri.getScheme().toLowerCase();
         switch ( scheme )
         {
-        case "bolt":
+        case BOLT_URI_SCHEME:
             assertNoRoutingContext( uri, routingSettings );
             return createDirectDriver( address, connectionPool, config, securityPlan, retryLogic );
-        case "bolt+routing":
+        case BOLT_ROUTING_URI_SCHEME:
             return createRoutingDriver( address, connectionPool, config, routingSettings, securityPlan, retryLogic );
         default:
             throw new ClientException( format( "Unsupported URI scheme: %s", scheme ) );

driver/src/main/java/org/neo4j/driver/v1/GraphDatabase.java

@@ -23,6 +23,9 @@
 import org.neo4j.driver.internal.DriverFactory;
 import org.neo4j.driver.internal.cluster.RoutingSettings;
 import org.neo4j.driver.internal.retry.RetrySettings;
+import org.neo4j.driver.v1.exceptions.ServiceUnavailableException;
+
+import static org.neo4j.driver.internal.DriverFactory.BOLT_ROUTING_URI_SCHEME;
 
 /**
  * Creates {@link Driver drivers}, optionally letting you {@link #driver(URI, Config)} to configure them.
@@ -131,4 +134,46 @@ public static Driver driver( URI uri, AuthToken authToken, Config config )
 
         return new DriverFactory().newInstance( uri, authToken, routingSettings, retrySettings, config );
     }
+
+    /**
+     * Try to create a bolt+routing driver from the <b>first</b> available address.
+     * This is wrapper for the {@link #driver} method that finds the <b>first</b>
+     * server to respond positively.
+     *
+     * @param routingUris an {@link Iterable} of server {@link URI}s for Neo4j instances. All given URIs should
+     * have 'bolt+routing' scheme.
+     * @param authToken authentication to use, see {@link AuthTokens}
+     * @param config user defined configuration
+     * @return a new driver instance
+     */
+    public static Driver routingDriver( Iterable<URI> routingUris, AuthToken authToken, Config config )
+    {
+        assertRoutingUris( routingUris );
+
+        for ( URI uri : routingUris )
+        {
+            try
+            {
+                return driver( uri, authToken, config );
+            }
+            catch ( ServiceUnavailableException e )
+            {
+                // try the next one
+            }
+        }
+
+        throw new ServiceUnavailableException( "Failed to discover an available server" );
+    }
+
+    private static void assertRoutingUris( Iterable<URI> uris )
+    {
+        for ( URI uri : uris )
+        {
+            if ( !BOLT_ROUTING_URI_SCHEME.equals( uri.getScheme() ) )
+            {
+                throw new IllegalArgumentException(
+                        "Illegal URI scheme, expected '" + BOLT_ROUTING_URI_SCHEME + "' in '" + uri + "'" );
+            }
+        }
+    }
 }

driver/src/test/java/org/neo4j/driver/v1/integration/CausalClusteringIT.java

@@ -22,6 +22,7 @@
 import org.junit.Test;
 
 import java.net.URI;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.Callable;
 import java.util.concurrent.CountDownLatch;
@@ -66,6 +67,7 @@
 import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
+import static org.neo4j.driver.internal.logging.DevNullLogging.DEV_NULL_LOGGING;
 import static org.neo4j.driver.v1.Values.parameters;
 
 public class CausalClusteringIT
@@ -85,6 +87,16 @@ public void shouldExecuteReadAndWritesWhenDriverSuppliedWithAddressOfLeader() th
         assertEquals( 1, count );
     }
 
+    @Test
+    public void shouldExecuteReadAndWritesWhenRouterIsDiscovered() throws Exception
+    {
+        Cluster cluster = clusterRule.getCluster();
+
+        int count = executeWriteAndReadThroughBoltOnFirstAvailableAddress( cluster.anyReadReplica(), cluster.leader() );
+
+        assertEquals( 1, count );
+    }
+
     @Test
     public void shouldExecuteReadAndWritesWhenDriverSuppliedWithAddressOfFollower() throws Exception
     {
@@ -446,6 +458,19 @@ private int executeWriteAndReadThroughBolt( ClusterMember member ) throws Timeou
         }
     }
 
+    private int executeWriteAndReadThroughBoltOnFirstAvailableAddress( ClusterMember... members ) throws TimeoutException, InterruptedException
+    {
+        List<URI> addresses = new ArrayList<>( members.length );
+        for ( ClusterMember member : members )
+        {
+            addresses.add( member.getRoutingUri() );
+        }
+        try ( Driver driver = discoverDriver( addresses ) )
+        {
+            return inExpirableSession( driver, createWritableSession( null ), executeWriteAndRead() );
+        }
+    }
+
     private Function<Driver,Session> createSession()
     {
         return new Function<Driver,Session>()
@@ -592,6 +617,15 @@ public Logger getLog( String name )
         return GraphDatabase.driver( boltUri, clusterRule.getDefaultAuthToken(), config );
     }
 
+    private Driver discoverDriver( List<URI> routingUris )
+    {
+        Config config = Config.build()
+                .withLogging( DEV_NULL_LOGGING )
+                .toConfig();
+
+        return GraphDatabase.routingDriver( routingUris, clusterRule.getDefaultAuthToken(), config );
+    }
+
     private static void createNodesInDifferentThreads( int count, final Driver driver ) throws Exception
     {
         final CountDownLatch beforeRunLatch = new CountDownLatch( count );

driver/src/test/java/org/neo4j/driver/v1/util/cc/LocalOrRemoteClusterRule.java

@@ -25,6 +25,8 @@
 import org.neo4j.driver.v1.AuthToken;
 import org.neo4j.driver.v1.AuthTokens;
 
+import static org.neo4j.driver.internal.DriverFactory.BOLT_ROUTING_URI_SCHEME;
+
 public class LocalOrRemoteClusterRule extends ExternalResource
 {
     private static final String CLUSTER_URI_SYSTEM_PROPERTY_NAME = "externalClusterUri";
@@ -88,7 +90,7 @@ private static void assertValidSystemPropertiesDefined()
                     "Both cluster uri and 'neo4j' user password system properties should be set. " +
                     "Uri: '" + uri + "', Password: '" + password + "'" );
         }
-        if ( uri != null && !"bolt+routing".equals( uri.getScheme() ) )
+        if ( uri != null && !BOLT_ROUTING_URI_SCHEME.equals( uri.getScheme() ) )
         {
             throw new IllegalStateException( "CLuster uri should have bolt+routing scheme: '" + uri + "'" );
         }