package org.drools;


/**
 * Interface invoke WorkingMemory methods within a callback. The concrete implementations
 * of this interface can provide various services related to the WorkingMemory instance
 * (eg, synchronization).
 */
public interface WorkingMemoryTemplate {

    /**
     * Callback interface for invoking WorkingMemory methods within a synchronized block.
     */
    public interface Callback {
        /**
         * Gets called by <code>WorkingMemorySynchronizedTemplate.execute</code> with a
         * WorkingMemory instance protected by a synchronized block.
         * @param workingMemory
         * @return Any object or null.
         */
        Object doInWorkingMemory(final WorkingMemory workingMemory) throws DroolsException;
    }

    /**
     * Invokes <code>Callback.doInWorkingMemory</code>. Any thrown <code>DroolsException<code> is
     * softened to <code>DroolsRuntimeException</code>.
     * @param callback
     * @return Any object or null.
     */
    Object execute(Callback callback);

}