ImpalaStandaloneConfiguration

Simple Startup

With Spring, a standalone Spring ApplicationContext will normally be set up using a call such as:

new ClassPathXmlApplicationContext(contextLocatons);

There is a little more indirection in the mechanism for starting up a standalone application context. The easiest way to do this is to use the static method:

Impala.init();

Advanced Startup

So how do we control how Impala is configured at startup time?

The class Impala is really itself just a very thin wrapper with static methods around OperationsFacade, which in turn is a facade to the various operations Impala exposes. Most of the implementations you are likely to use extends BaseOperationsFacade. This class defines an abstract method

protected abstract List<String> getBootstrapContextLocations();

which the concrete class will need to implement. The default implementation used is BootstrappingOperationFacade.

As with web-based Impala applications, this implementation uses a two pronged approached to configuring Impala at runtime.

• For built-in Impala capabilities, configuration can be applied by setting properties, typically

using entries in impala.properties. For more details, see PropertyConfiguration.

• For introducing extensions into the Impala runtime, new Spring application context XML files can be added with additional

beans to be loaded. This is described in more detail in BootstrapContexts.

It is straightforward to change the actual implementation class used through the system property FacadeConstants.FACADE_CLASS_NAME, which translates to FacadeConstants.facade.class.name. For example, when using the interactive test runner, a different OperationsFacade subclass is used.