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License Apache Software License 2.0
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Authored by:

Andres Almiray
aalmiray@yahoo.com

The HBase plugin enables lightweight access to HBase databases. This plugin does NOT provide domain classes nor dynamic finders like GORM does.

Usage

Upon installation the plugin will generate the following artifacts in $appdir/griffon-app/conf:

  • HBaseConfig.groovy - contains the database definitions.
  • BootstrapHBase.groovy - defines init/destroy hooks for data to be manipulated during app startup/shutdown.

Two dynamic methods named withHBase and withHTable will be injected into all controllers, giving you access to a org.apache.hadoop.conf.Configuration object, with which you'll be able to make calls to the database. Remember to make all database calls off the UI thread otherwise your application may appear unresponsive when¨doing long computations inside the UI thread.

This method is aware of multiple databases. If no configurationName is specified when calling it then the default database will be selected. Here are two example usages, the first queries against the default database while the second queries a database whose name has been configured as 'internal'

package sample
class SampleController {
    def queryAllDatabases = {
        withHBase { configName, configuration -> ... }
        withHBase('internal') { configName, configuration -> ... }
    }
}

Querying a particular table can be done in the following way

package sample
class SampleController {
    def queryPersonTable = {
        withHTable('person') { configName, configuration, tableName, htable -> ... }
        withHTable('default', 'person') { configName, configuration, tableName, htable -> ... }
    }
} 

The following list enumerates all the variants of the injected method

  • <R> R withHBase(Closure<R> stmts)
  • <R> R withHBase(CallableWithArgs<R> stmts)
  • <R> R withHBase(String configurationName, Closure<R> stmts)
  • <R> R withHBase(String configurationName, CallableWithArgs<R> stmts)
  • <R> R withHTable(String tableName, Closure<R> stmts)
  • <R> R withHTable(String tableName, CallableWithArgs<R> stmts)
  • <R> R withHTable(String configurationName, String tableName, Closure<R> stmts)
  • <R> R withHTable(String configurationName, String tableName, CallableWithArgs<R> stmts)

These methods are also accessible to any component through the singleton griffon.plugins.hbase.HBaseConnector. You can inject these methods to non-artifacts via metaclasses. Simply grab hold of a particular metaclass and call HBaseEnhancer.enhance(metaClassInstance, hbaseProviderInstance).

Configuration

HBaseAware AST Transformation

The preferred way to mark a class for method injection is by annotating it with @griffon.plugins.hbase.HBaseAware. This transformation injects the griffon.plugins.hbase.HBaseContributionHandler interface and default behavior that fulfills the contract.

Dynamic method injection

Dynamic methods will be added to controllers by default. You can change this setting by adding a configuration flag in griffon-app/conf/Config.groovy

griffon.hbase.injectInto = ['controller', 'service']

Dynamic method injection will be skipped for classes implementing griffon.plugins.hbase.HBaseContributionHandler.

Events

The following events will be triggered by this addon

  • HBaseConnectStart[config, configurationName] - triggered before connecting to the database
  • HBaseConnectEnd[configurationName, configuration] - triggered after connecting to the database
  • HBaseDisconnectStart[config, configurationName, configuration] - triggered before disconnecting from the database
  • HBaseDisconnectEnd[config, configurationName] - triggered after disconnecting from the database

Multiple Databases

The config file HBaseConfig.groovy defines a default database block. As the name implies this is the database used by default, however you can configure named databases by adding a new config block. For example connecting to a database whose name is 'internal' can be done in this way

datastore {
    internal {
        resources = [
            '/opt/hbase/conf/hbase-site.xml'
        ]
    }
}

This block can be used inside the environments() block in the same way as the default database block is used.

Configuration Storage

The plugin will load and store the contents of HBaseConfig.groovy inside the application's configuration, under the pluginConfig namespace. You may retrieve and/or update values using

app.config.pluginConfig.hbase

Connect at Startup

The plugin will attempt a connection to the default database at startup. If this behavior is not desired then specify the following configuration flag in Config.groovy

griffon.hbase.connect.onstartup = false

Example

A trivial sample application can be found at https://github.com/aalmiray/griffon_sample_apps/tree/master/persistence/hbase

Testing

Dynamic methods will not be automatically injected during unit testing, because addons are simply not initialized for this kind of tests. However you can use HBaseEnhancer.enhance(metaClassInstance, hbaseProviderInstance) where hbaseProviderInstance is of type griffon.plugins.hbase.HBaseProvider. The contract for this interface looks like this

public interface HBaseProvider {
    <R> R withHBase(Closure<R> closure);
    <R> R withHBase(CallableWithArgs<R> callable);
    <R> R withHBase(String configurationName, Closure<R> closure);
    <R> R withHBase(String configurationName, CallableWithArgs<R> callable);
    <R> R withHTable(String tableName, Closure<R> closure);
    <R> R withHTable(String tableName, CallableWithArgs<R> callable);
    <R> R withHTable(String configurationName, String tableName, Closure<R> closure);
    <R> R withHTable(String configurationName, String tableName, CallableWithArgs<R> callable);
}

It's up to you define how these methods need to be implemented for your tests. For example, here's an implementation that never fails regardless of the arguments it receives

class MyHBaseProvider implements HBaseProvider {
    public <R> R withHBase(Closure<R> closure) { null }
    public <R> R withHBase(CallableWithArgs<R> callable) { null }
    public <R> R withHBase(String configurationName, Closure<R> closure) { null }
    public <R> R withHBase(String configurationName, CallableWithArgs<R> callable) { null }
    public <R> R withHTable(String tableName, Closure<R> closure) { null }
    public <R> R withHTable(String tableName, CallableWithArgs<R> callable) { null }
    public <R> R withHTable(String configurationName, String tableName, Closure<R> closure) { null }
    public <R> R withHTable(String configurationName, String tableName, CallableWithArgs<R> callable) { null }
}

This implementation may be used in the following way

class MyServiceTests extends GriffonUnitTestCase {
    void testSmokeAndMirrors() {
        MyService service = new MyService()
        HBaseEnhancer.enhance(service.metaClass, new MyHBaseProvider())
        // exercise service methods
    }
}

On the other hand, if the service is annotated with @HBaseAware then usage of HBaseEnhancer should be avoided at all costs. Simply set hbaseProviderInstance on the service instance directly, like so, first the service definition

@griffon.plugins.hbase.HBaseAware
class MyService {
    def serviceMethod() { ... }
}

Next is the test

class MyServiceTests extends GriffonUnitTestCase {
    void testSmokeAndMirrors() {
        MyService service = new MyService()
        service.hbaseProvider = new MyHBaseProvider()
        // exercise service methods
    }
}

Tool Support

DSL Descriptors

This plugin provides DSL descriptors for Intellij IDEA and Eclipse (provided you have the Groovy Eclipse plugin installed). These descriptors are found inside the griffon-hbase-compile-x.y.z.jar, with locations

  • dsdl/hbase.dsld
  • gdsl/hbase.gdsl

Lombok Support

Rewriting Java AST in a similar fashion to Groovy AST transformations is possible thanks to the lombok plugin.

JavaC

Support for this compiler is provided out-of-the-box by the command line tools. There's no additional configuration required.

Eclipse

Follow the steps found in the Lombok plugin for setting up Eclipse up to number 5.

  1. Go to the path where the lombok.jar was copied. This path is either found inside the Eclipse installation directory or in your local settings. Copy the following file from the project's working directory

     $ cp $USER_HOME/.griffon/<version>/projects/<project>/plugins/hbase-<version>/dist/griffon-hbase-compile-<version>.jar .
    
  2. Edit the launch script for Eclipse and tweak the boothclasspath entry so that includes the file you just copied

    -Xbootclasspath/a:lombok.jar:lombok-pg-<version>.jar:        griffon-lombok-compile-<version>.jar:griffon-hbase-compile-<version>.jar
    
  3. Launch Eclipse once more. Eclipse should be able to provide content assist for Java classes annotated with @HBaseAware.

NetBeans

Follow the instructions found in Annotation Processors Support in the NetBeans IDE, Part I: Using Project Lombok. You may need to specify lombok.core.AnnotationProcessor in the list of Annotation Processors.

NetBeans should be able to provide code suggestions on Java classes annotated with @HBaseAware.

Intellij IDEA

Follow the steps found in the Lombok plugin for setting up Intellij IDEA up to number 5.

  1. Copy griffon-hbase-compile-<version>.jar to the lib directory

     $ pwd
       $USER_HOME/Library/Application Support/IntelliJIdea11/lombok-plugin
     $ cp $USER_HOME/.griffon/<version>/projects/<project>/plugins/hbase-<version>/dist/griffon-hbase-compile-<version>.jar lib
    
  2. Launch IntelliJ IDEA once more. Code completion should work now for Java classes annotated with @HBaseAware.