Can not connect to graph with Cassandra as backend

[代栋]

Hi, all, I am writing a java client with Titan to connect to a Cassandra cluster as backend server. Things got broken and I can not figure out why. Thanks very much if you can help me here. 

I am trying the Remote Server Mode. I installed Cassandra cluster which operates well using cqlsh tool. It is 3.0.1.

After that, I created a maven project with dependencies including: titan-core(1.0.0) and titan-cassandra(1.0.0).

I follow the page:http://s3.thinkaurelius.com/docs/titan/1.0.0/cassandra.html to init the graph like this:

TitanGraph graph = TitanFactory.build().
set("storage.backend", "cassandra").
set("storage.hostname", "77.77.77.77").
open();

It replies me with this error:

SLF4J: Class path contains multiple SLF4J bindings.

SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.

SLF4J: Actual binding is of type [ch.qos.logback.classic.util.ContextSelectorStaticBinder]

12:06:09.689 [main] DEBUG c.t.t.d.c.a.AstyanaxStoreManager - About to instantiate class public com.netflix.astyanax.connectionpool.impl.FixedRetryBackoffStrategy(int,int) with 2 arguments

12:06:09.692 [main] DEBUG c.t.t.d.c.a.AstyanaxStoreManager - Instantiated RetryBackoffStrategy object com.netflix.astyanax.connectionpool.impl.FixedRetryBackoffStrategy@543788f3 from config string "com.netflix.astyanax.connectionpool.impl.FixedRetryBackoffStrategy,1000,5000"

12:06:09.693 [main] DEBUG c.t.t.d.c.a.AstyanaxStoreManager - About to instantiate class public com.netflix.astyanax.retry.BoundedExponentialBackoff(long,long,int) with 3 arguments

12:06:09.694 [main] DEBUG c.t.t.d.c.a.AstyanaxStoreManager - Instantiated RetryPolicy object com.netflix.astyanax.retry.BoundedExponentialBackoff@15bfd87[maxSleepTimeMs=25000,MAX_SHIFT=30,random=java.util.Random@3d0f8e03,baseSleepTimeMs=100,maxAttempts=8,attempts=0] from config string "com.netflix.astyanax.retry.BoundedExponentialBackoff,100,25000,8"

12:06:09.705 [main] DEBUG c.t.t.d.c.a.AstyanaxStoreManager - Custom RetryBackoffStrategy com.netflix.astyanax.connectionpool.impl.FixedRetryBackoffStrategy@543788f3

12:06:09.906 [main] INFO  c.n.a.c.i.ConnectionPoolMBeanManager - Registering mbean: com.netflix.MonitoredResources:type=ASTYANAX,name=ClusterTitanConnectionPool,ServiceType=connectionpool

12:06:09.915 [main] INFO  c.n.a.c.i.CountingConnectionPoolMonitor - AddHost: 128.110.96.155

12:06:09.931 [pool-4-thread-1] DEBUG c.n.astyanax.thrift.ThriftConverter - java.net.ConnectException: Connection refused

12:06:19.924 [main] DEBUG c.t.t.d.c.a.AstyanaxStoreManager - Failed to describe keyspace titan

12:06:19.933 [main] DEBUG c.t.t.d.c.a.AstyanaxStoreManager - Creating keyspace titan...

12:06:19.957 [pool-4-thread-1] DEBUG c.n.astyanax.thrift.ThriftConverter - java.net.ConnectException: Connection refused

Is there any reason causing this connection refused?

After googling a while, i also tried cassandrathrift as the backend server, but it still fails, with a different error:

Exception in thread "main" java.lang.IllegalArgumentException: Could not instantiate implementation: com.thinkaurelius.titan.diskstorage.cassandra.thrift.CassandraThriftStoreManager

at com.thinkaurelius.titan.util.system.ConfigurationUtil.instantiate(ConfigurationUtil.java:55)

at com.thinkaurelius.titan.diskstorage.Backend.getImplementationClass(Backend.java:473)

at com.thinkaurelius.titan.diskstorage.Backend.getStorageManager(Backend.java:407)

at com.thinkaurelius.titan.graphdb.configuration.GraphDatabaseConfiguration.<init>(GraphDatabaseConfiguration.java:1320)

at com.thinkaurelius.titan.core.TitanFactory.open(TitanFactory.java:94)

at com.thinkaurelius.titan.core.TitanFactory.open(TitanFactory.java:84)

at com.thinkaurelius.titan.core.TitanFactory$Builder.open(TitanFactory.java:139)

at edu.prism.TitanApp.initConnection(TitanApp.java:12)

at edu.prism.TitanApp.main(TitanApp.java:20)

Caused by: java.lang.reflect.InvocationTargetException

at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)

at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)

at java.lang.reflect.Constructor.newInstance(Constructor.java:422)

at com.thinkaurelius.titan.util.system.ConfigurationUtil.instantiate(ConfigurationUtil.java:44)

... 8 more

Caused by: com.thinkaurelius.titan.diskstorage.TemporaryBackendException: Temporary failure in storage backend

at com.thinkaurelius.titan.diskstorage.cassandra.thrift.CassandraThriftStoreManager.getCassandraPartitioner(CassandraThriftStoreManager.java:208)

at com.thinkaurelius.titan.diskstorage.cassandra.thrift.CassandraThriftStoreManager.<init>(CassandraThriftStoreManager.java:186)

... 13 more

Caused by: org.apache.thrift.transport.TTransportException: java.net.ConnectException: Connection refused

at org.apache.thrift.transport.TSocket.open(TSocket.java:187)

at org.apache.thrift.transport.TFramedTransport.open(TFramedTransport.java:81)

at com.thinkaurelius.titan.diskstorage.cassandra.thrift.thriftpool.CTConnectionFactory.makeRawConnection(CTConnectionFactory.java:88)

at com.thinkaurelius.titan.diskstorage.cassandra.thrift.thriftpool.CTConnectionFactory.makeObject(CTConnectionFactory.java:52)

at com.thinkaurelius.titan.diskstorage.cassandra.thrift.thriftpool.CTConnectionFactory.makeObject(CTConnectionFactory.java:21)

at org.apache.commons.pool.impl.GenericKeyedObjectPool.borrowObject(GenericKeyedObjectPool.java:1220)

at com.thinkaurelius.titan.diskstorage.cassandra.thrift.CassandraThriftStoreManager.getCassandraPartitioner(CassandraThriftStoreManager.java:205)

... 14 more

Caused by: java.net.ConnectException: Connection refused

at java.net.PlainSocketImpl.socketConnect(Native Method)

at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)

at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)

at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)

at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)

at java.net.Socket.connect(Socket.java:589)

at org.apache.thrift.transport.TSocket.open(TSocket.java:182)

... 20 more

Any suggestion will be great! And, most importantly, I find it is very hard to find some example codes for Titan-1.0.0 using Java. There are all kinds of different APIs and ways to write Titan client codes. I am not sure which one will work and I am not sure whether they are good for the latest version of Titan. Could you please give me some reference implementation if you are aware of some?

thanks!

- Dong

[David]

package example.com;

import java.util.Iterator;

import com.thinkaurelius.titan.core.TitanFactory;
import com.thinkaurelius.titan.core.TitanGraph;
import org.apache.commons.configuration.BaseConfiguration;

import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversalSource;

import org.apache.tinkerpop.gremlin.structure.Edge;
import org.apache.tinkerpop.gremlin.structure.Vertex;
import org.apache.tinkerpop.gremlin.structure.VertexProperty;

/**
 * Basic Java Program For Titan 1.X on Cassandra 2.2.3
 * NO idea if this runs on Cassandra 3.x
 * Anything past 2.1.9 is a bit risky at the moment
 */
public class SampleTitanProgram
{
    public static void main(String args[])
    {
        SampleTitanProgram me = new SampleTitanProgram();
        me.doWork();
    }

    private void doWork()
    {
        TitanGraph tg = null;
        try
        {
            // build up a configuration.
            BaseConfiguration conf = new BaseConfiguration();
            // or cassandra
            conf.setProperty("storage.backend", "cassandrathrift");
            conf.setProperty("storage.hostname", "11.95.61.231,11.95.61.230,11.95.61.238");
            conf.setProperty("storage.cassandra.keyspace", "titan");

            tg = TitanFactory.open(conf);
            Vertex v1 = tg.addVertex("keyone", "valueone");
            Vertex v2 = tg.addVertex("keytwo", "valuetwo");

            Edge e1 = v1.addEdge("fromOneToTwo", v2, "weight", 1.0);

            GraphTraversalSource gts = tg.traversal();
            Vertex v3 = gts.V().has("keyone", "valueone").out().next();

            Iterator<VertexProperty<String>> itr1 = v3.properties();
            while (itr1.hasNext())
            {
                VertexProperty vp = itr1.next();
                System.out.println("key value pair is: " + vp.key() + ": " + vp.value());
            }
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
        finally
        {
            // should check if tg is null first
            tg.close();
        }
    }
}

testit.jar in the execution line contains the compiled class above.

Put all jars in titan lib directory in your classpath in addition to testit.jar to run this:

java -cp /whateverpath/titanbuild/titan/lib/*:/whateverpath/testit.jar com.example.SampleTitanProgram

[David]

Error correction

java -cp /whateverpath/titanbuild/titan/lib/*:/whateverpath/testit.jar example.com.SampleTitanProgram

[Jason Plurad]

Hi Dong,

Your stack traces are showing ConnectionExceptions to Cassandra over thrift. You didn't mention what version of Cassandra you have, but make sure you enable thrift on your Cassandra nodes. It is disabled by default on Cassandra 2.2 and higher.

1. update ./conf/cassandra.yaml before starting the node

# Whether to start the thrift rpc server.
start_rpc: true

# The address or interface to bind the Thrift RPC service and native transport
# server to.
#
# Set rpc_address OR rpc_interface, not both. Interfaces must correspond
# to a single address, IP aliasing is not supported.
#
rpc_address: 77.77.77.77

2. or if the node is already running

./bin/nodetool enablethrift

-- Jason

[Laxmikant Patil]

Hi David,

Here in your code you are creating graph. But how does it actually stored in Cassandra? How do I retrieve it later if I just want to use it later?

[Stephen Mallette]

I'm not sure what you are asking, but a TitanGraph is an abstraction over databases like Cassandra.  When you make method calls on it, like addVertex(), to build your graph it stores that data there on commit.  You would only later access that data through a TitanGraph instance - the data is encoded in cassandra so you won't be able to easily make sense of it with CQL or anything like that.

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