Package com.wles.blm.pool

API for managing the BLMContextManager Pool.

See:
Description

Interface Summary

BLMContextValidator

Validates an instance of BLMContextManager object.

Class Summary

BLMContextFactory	Implements PoolableObjectFactory for managing BLMContextManager instances.
CallBasedContextValidator	Validates BLM Context Manager by calling the BLMDeclarationManager.getKind(String) method.

Package com.wles.blm.pool Description

API for managing the BLMContextManager Pool.

The com.wles.blm.pool package defines BLM API for pooling of BLMContextManager objects. The API is extends the Apache Common Pool Framework.

Here is a simple example of using the pool. Steps that are optional are marked as (Optional}.

  public class PoolHolder
  {
    public static GenericObjectPool blmContextPool = null; 
	
    //Initialize the pool
    public static synchronized void init(String blmUrl, String username, String password) {
      
      //Initialize only once
      if (blmContextPool == null)
        return;
        
      // Step 1. (Optional)
      // Create a BLMContextManager validator
		
      CallBasedContextValidator blmContextValidator = new CallBasedContextValidator();

      // Step 2.
      // Create the BLMContext factory.
      // The factory is responsible for creating, destroying and validating of BLMContextManager instances.
      
      BLMContextFactory blmContextFactory = new BLMContextFactory(
      			blmUrl, username, password, blmContextValidator, 5);
      
      // Step 3. (Optional)
      // Create configuration for the pool.
      // Please see set methods of GenericObjectPool for more information on different pool parameters.
      // See also default values at http://jakarta.apache.org/commons/pool/apidocs/constant-values.html.
      
      GenericObjectPool.Config config = new GenericObjectPool.Config();
      
      // The maximum number of objects that can be borrowed from the pool at one time.
      config.maxActive = 5;
      
      // The maximum number of objects that can sit idle in the pool at any time.
      config.maxIdle = -1; //unlimited
		
      // The behaviour of the GenericObjectPool method when the pool is exhausted
      config.whenExhaustedAction = GenericObjectPool.WHEN_EXHAUSTED_BLOCK; //wait
      
      // The maximum amount of time (in milliseconds) the borrowObject() method should block before throwing an exception. 
      config.maxWait = -1; //unlimited
      
      // When true, objects will be validated before being returned by the borrowObject() method.
      config.testOnBorrow = true;
      
      // When true, objects will be validated before being returned to the pool within the returnObject(java.lang.Object). 
      config.testOnReturn = false;
      
      // The following parameters affect the background eviction thread
      
      // The number of milliseconds to sleep between runs of the idle object evictor thread.
      // When non-positive, no idle object evictor thread will be run.
      config.timeBetweenEvictionRunsMillis = 1000 * 60 * 5; //Every 5 minutes
      
      // The minimum amount of time an object may sit idle in the pool before it is eligable for eviction
      config.minEvictableIdleTimeMillis = 1000 * 60 * 60; //An hour
      
      // The minimum amount of time an object may sit idle in the pool before it is eligable for eviction.
      // With the extra condition that at least "minIdle" amount of object remain in the pool.
      config.softMinEvictableIdleTimeMillis = 1000 * 60 * 10; //Ten minutes
      
      // When true, objects will be validated by the idle object evictor.
      config.testWhileIdle = false;
      
      // Sets the max number of objects to examine during each run of the idle object evictor thread (if any).
      config.numTestsPerEvictionRun = 5;
      
      // Sets the minimum number of objects allowed in the pool.
      // Setting this number may improve performance because the pool will contain pre-loaded context managers.
      config.minIdle = 2;
      
      // Step 4.
      // Create the pool
      
      blmContextPool = new GenericObjectPool(blmContextFactory, config);		
    }
  }

A class that makes use of a BLMContextManager could then use the pool as shown below:

  public class Foo
  {
    private ObjectPool pool;
    public Foo()
    {
      PoolHolder.init("https://blmserver:7011", "system", "weblogic");
      pool = PoolHolder.blmContextPool;
    }

    public doSomething()
    {
      ...
      BLMContextManager context = null;
      try
      {
        context = (BLMContextManager) pool.borrowObject();
        // use the context
        ...
      }
      finally
      {
        if (context != null)
        {
          pool.returnObject(context);
        }
      }
      ...
    }
  }