I am trying to setup Titan (server 0.4.4) with Cassandra embedded. My environment is Windows 8.1 x64 + Cygwin. The install is in E:\titan-server-0.4.4.
I also need to be able to access this setup via Rexster.
For my configuration, I referred to https://github.com/thinkaurelius/titan/wiki/Using-Cassandra.
I've modified graph configuration
E:\titan-server-0.4.4\conf\rexster-cassandra-es.xml
graph section to
<graph>
<graph-name>graph</graph-name>
<graph-type>com.thinkaurelius.titan.tinkerpop.rexster.TitanGraphConfiguration</graph-type>
<graph-read-only>false</graph-read-only>
<properties>
<auto-type>none</auto-type>
<storage.batch-loading>true</storage.batch-loading>
<storage.cassandra-config-dir>file:///E:\titan-server-0.4.4\conf\cassandra.yaml</storage.cassandra-config-dir>
<storage.backend>embeddedcassandra</storage.backend>
<storage.index.search.backend>elasticsearch</storage.index.search.backend>
<storage.index.search.directory>../db/es</storage.index.search.directory>
<storage.index.search.client-only>false</storage.index.search.client-only>
<storage.index.search.local-mode>true</storage.index.search.local-mode>
</properties>
<extensions>
<allows>
<allow>tp:gremlin</allow>
</allows>
</extensions>
</graph>
(Note
<auto-type>none</auto-type>
<storage.batch-loading>true</storage.batch-loading>
these are to allow bulk insert. The whole idea of embedded Cassandra is to improve the insertion performance.)
However, when I tried starting the service with ./bin/titan.sh -v start, the start failed with:
org.apache.cassandra.exceptions.ConfigurationException: localhost/127.0.0.1:7000 is in use by another process. Change listen_address:storage_port in cassandra.yaml to values that do not conflict with other services at org.apache.cassandra.net.MessagingService.getServerSocket(MessagingService.java:439) at org.apache.cassandra.net.MessagingService.listen(MessagingService.java:387) at org.apache.cassandra.service.StorageService.joinTokenRing(StorageService.java:549) at org.apache.cassandra.service.StorageService.initServer(StorageService.java:514) at org.apache.cassandra.service.StorageService.initServer(StorageService.java:411) at org.apache.cassandra.service.CassandraDaemon.setup(CassandraDaemon.java:278) at org.apache.cassandra.service.CassandraDaemon.activate(CassandraDaemon.java:366) at org.apache.cassandra.service.CassandraDaemon.main(CassandraDaemon.java:409) at com.thinkaurelius.titan.diskstorage.cassandra.utils.CassandraDaemonWrapper.start(CassandraDaemonWrapper.java:51) at com.thinkaurelius.titan.diskstorage.cassandra.embedded.CassandraEmbeddedStoreManager.(CassandraEmbeddedStoreManager.java:102) 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:408) at com.thinkaurelius.titan.diskstorage.Backend.instantiate(Backend.java:344) at com.thinkaurelius.titan.diskstorage.Backend.getImplementationClass(Backend.java:367) at com.thinkaurelius.titan.diskstorage.Backend.getStorageManager(Backend.java:311) at com.thinkaurelius.titan.diskstorage.Backend.(Backend.java:121) at com.thinkaurelius.titan.graphdb.configuration.GraphDatabaseConfiguration.getBackend(GraphDatabaseConfiguration.java:1173) at com.thinkaurelius.titan.graphdb.database.StandardTitanGraph.(StandardTitanGraph.java:75) at com.thinkaurelius.titan.core.TitanFactory.open(TitanFactory.java:40) at com.thinkaurelius.titan.tinkerpop.rexster.TitanGraphConfiguration.configureGraphInstance(TitanGraphConfiguration.java:25) at com.tinkerpop.rexster.config.GraphConfigurationContainer.getGraphFromConfiguration(GraphConfigurationContainer.java:119) at com.tinkerpop.rexster.config.GraphConfigurationContainer.(GraphConfigurationContainer.java:54) at com.tinkerpop.rexster.server.XmlRexsterApplication.reconfigure(XmlRexsterApplication.java:99) at com.tinkerpop.rexster.server.XmlRexsterApplication.(XmlRexsterApplication.java:47) at com.tinkerpop.rexster.Application.(Application.java:96) at com.tinkerpop.rexster.Application.main(Application.java:188) localhost/127.0.0.1:7000 is in use by another process. Change listen_address:storage_port in cassandra.yaml to values that do not conflict with other services
I tried mofiying the ports in "E:\titan-server-0.4.4\conf\cassandra.yaml", but after some investigation, I've realized that the port is actually taken by Cassandra itself, i.e. in this configuration, ./bin/titan.sh -v start tries to start multiple instances of Cassandra?!
I copied cassandra.yaml to cassandra2.yaml with different port settings and specified path to cassandra2.yaml in the graph configuration xml. After this, I was able to start Rexster with Titan and Cassandra embedded by running ./bin/titan.sh -v start.
However, I strongly believe that something is wrong with this setup. Besides, the system does not behave well - sometime I cannot save a graph in Rexster's (Web based) Gremlin shell by using g.commit() - the command succeeds, but nothing gets saved.
So is the right way to run Titan with Cassandra embedded? What is the configuration supposed to be?
If you use Titan server via the shell or bat script, it will automatically start a Titan instance for you and attempt to connect to it over localhost. When you configured it to use Cassandra embedded, the two instances naturally conflict.
Is there a particular reason you want to use Cassandra embedded. I'd strongly encourage you to try the out-of-the-box version first. Cassandra embedded is mostly meant for low latency applications and requires a solid understanding of the JVM.
Good luck!