HBase Configuration

NeoEMF HBase implementation allows to store and distribute models in a HBase cluster. Compared to Blueprints and MapDB implementations that rely on embedded databases that are instantiated by the framework, the HBase implementation requires to access an existing HBase server to store a model. We detail here how to setup and start a HBase server locally, and access it through NeoEMF.

This page is based on the Apache HBase tutorial available on HBase website.

Download HBase

HBase is not bundled with NeoEMF and has to be downloaded separately. Note that NeoEMF has been tested for HBase versions between 0.98 and 1.3.1 (latest version available at the moment), if you have another installed version you may experience compatibility issues. Extract the downloaded zip file containing HBase binaries.

Start HBase

You are required to set JAVA_HOME environment variable before starting HBase. You can set the variable via your operating system’s usual mechanism, but HBase provides a central mechanism, conf/hbase-env.sh. Edit this file, uncomment the line starting with JAVA_HOME, and set it to the appropriate location for your operating system. The JAVA_HOME variable should be set to a directory which contains the executable file bin/java.

You can now start HBase using the following commands:

cd hbase_directory/bin
./start-hbase.sh

You should see a message prompted in the console stating that the master node has been started, and a path referencing HBase logs.

NOTE: The default configuration of HBase uses the tmp folder to store data. This folder is typically erase upon operating system's reboot. You can specify a folder to HBase by editing the file conf/hbase-site.xml with the following properties:

<configuration>
  <property>
    <name>hbase.rootdir</name>
    <value>file:///home/testuser/hbase</value>
  </property>
  <property>
    <name>hbase.zookeeper.property.dataDir</name>
    <value>/home/testuser/zookeeper</value>
  </property>
</configuration>

Verify HBase is Running

You can monitor HBase by checking http://localhost:16010. The database provides a web interface presenting monitoring information, existing tables, etc.

In addition, you can run ./hbase shell from the bin directory of your installation to start a dedicated shell to interact with the database. Information on how to use the HBase console is available on the HBase tutorial.

Create a NeoEMF HBase Resource

Once HBase a started, you can use it to store and load NeoEMF resources using the following code. NeoEMF provides the HBaseUri utility class that allows to create an URI containing HBase host, port, and an embedded URI representing the name of the model. Note that 2181 is the default port used to connect to HBase.

ImmutableConfig config = new HBaseConfig();
URI uri = new HBaseUriFactory().createRemoteUri("localhost", 2181, "hbaseModel");

ResourceSet resourceSet = new ResourceSetImpl();
Resource resource = resourceSet.createResource(uri);
resource.load(config.asMap());

// Manipulate the resource using the standard EMF API
resource.getContents()

// [...]

resource.save(config.asMap());
resource.unload();