ExecutionStrategy.java

package org.springframework.roo.shell;

/**
 * Strategy interface to permit the controlled execution of methods.
 * <p>
 * This interface is used to enable a {@link Shell} to execute methods in a
 * consistent, system-wide manner. A typical use case is to ensure user
 * interface commands are not executed concurrently when other background
 * threads are performing certain operations.
 * 
 * @author Ben Alex
 * @since 1.0
 */
public interface ExecutionStrategy {

  /**
   * Executes the method indicated by the {@link ParseResult}.
   * 
   * @param parseResult that should be executed (never presented as null)
   * @return an object which will be rendered by the {@link Shell}
   *         implementation (may return null)
   * @throws RuntimeException which is handled by the {@link Shell}
   *             implementation
   */
  Object execute(ParseResult parseResult) throws RuntimeException;

  /**
   * Indicates commands are able to be presented. This generally means all
   * important system startup activities have completed.
   * 
   * @return whether commands can be presented for processing at this time
   */
  boolean isReadyForCommands();

  /**
   * Indicates the execution runtime should be terminated. This allows it to
   * cleanup before returning control flow to the caller. Necessary for clean
   * shutdowns.
   */
  void terminate();
}