com.ibm.websphere.command
Class TargetableCommandImpl

java.lang.Object
  |
  +--com.ibm.websphere.command.TargetableCommandImpl

All Implemented Interfaces:

Command, java.io.Serializable, TargetableCommand

public abstract class TargetableCommandImpl

extends java.lang.Object

implements TargetableCommand

The TargetableCommandImpl class implements the generic methods in the TargetableCommand interface. Application programmers must implement the application-specific methods. The TargetableCommand interface provides support for the remote execution of commands, and the TargetableCommandImpl class provides a runtime for command execution.

All targetable commands extend the TargetableCommandImpl class.

See Also:

Serialized Form

Field Summary

protected CommandTarget	commandTarget The target object for the command.
protected java.lang.String	commandTargetName The name of the target object for the command.
protected boolean	hasOutputProperties Indicates if the command has output properties.
static java.lang.String	LOCAL A target object that executes a command within the client's JVM.
protected static TargetPolicy	targetPolicy The target policy used by the command to determine the target associated with the command.

Fields inherited from interface com.ibm.websphere.command.Command

serialVersionUID

Constructor Summary

TargetableCommandImpl()

Method Summary

void	execute() Executes the task encapsulated by the command.
CommandTarget	getCommandTarget() Returns the target object for the command.
java.lang.String	getCommandTargetName() Returns the name of the target object for the command.
static TargetPolicy	getTargetPolicy() Returns the target policy for the command.
boolean	hasOutputProperties() Indicates if the command has any output properties that will have to be returned to the client.
abstract boolean	isReadyToCallExecute() Indicates if all required input properties have been set.
abstract void	performExecute() Runs the business logic that makes up the command.
abstract void	reset() Sets the output properties to the values they had before the the execute method was run.
void	setCommandTarget(CommandTarget commandTarget) Sets the target object on the command.
void	setCommandTargetName(java.lang.String commandTargetName) Sets the name of the target object on the command.
void	setHasOutputProperties(boolean inProp) Sets the hasOutputProperties class variable to indicate if the command has output properties that must be returned to the client.
void	setOutputProperties(TargetableCommand fromCommand) Sets the return values on the command.
static void	setTargetPolicy(TargetPolicy targetPolicy) Sets the target policy for the command.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LOCAL

public static java.lang.String LOCAL

A target object that executes a command within the client's JVM. This implementation is provided in the LocalTarget class.

This is static so that it is easy to obtain.

targetPolicy

protected static TargetPolicy targetPolicy

The target policy used by the command to determine the target associated with the command. The default value is an instance of the TargetPolicyDefault class.

This is static so that it is easy to obtain.

commandTarget

protected transient CommandTarget commandTarget

The target object for the command.

commandTargetName

protected java.lang.String commandTargetName

The name of the target object for the command. The name is a fully qualified name for a Java class, for example, mypkg.bp.MyBusinessCmdTarget.

hasOutputProperties

protected boolean hasOutputProperties

Indicates if the command has output properties. Defaults to true. Can be set to false to eliminate unecessary copying and remote invocations.

Constructor Detail

TargetableCommandImpl

public TargetableCommandImpl()

Method Detail

execute

public void execute()
             throws CommandException

Executes the task encapsulated by the command. This is the default implementation for the execute() method in the Command interface, but it can be overridden by the application programmer.

This implementation of the execute() method does the following:

• Throws an UnsetInputPropertiesException if the isReadyToCallExecute method returns false for the command.
• Gets the target for the command according to the target policy.
• Invokes the executeCommand() method on the target, which in turn calls the performExecute() method on the command.
• Copies output values by using the setOutputProperties() method if the hasOutputProperties() method returns true and if the returned command is not the same instance as this command.

Specified by:

execute in interface Command

Throws:

CommandException - The superclass for all command exceptions. Specificially, UnsetInputPropertiesException is thrown if this command's isReadyToCallExecute() method returns false.

getCommandTarget

public CommandTarget getCommandTarget()

Returns the target object for the command. This implements the getCommandTarget() method declared in the TargetableCommand interface.

Specified by:

getCommandTarget in interface TargetableCommand

Returns:

The target object, which locates the server where the command will run.

getCommandTargetName

public java.lang.String getCommandTargetName()

Returns the name of the target object for the command. This implements the getCommandTargetName() method declared in the TargetableCommand interface.

Specified by:

getCommandTargetName in interface TargetableCommand

Returns:

The fully qualified name of the Java class of the target object.

getTargetPolicy

public static TargetPolicy getTargetPolicy()

Returns the target policy for the command.

hasOutputProperties

public final boolean hasOutputProperties()

Indicates if the command has any output properties that will have to be returned to the client. This implements the hasOutputProperties() method in the TargetableCommand interface.

Specified by:

hasOutputProperties in interface TargetableCommand

Returns:

The value true if the command has output properties that must be copied back to the client.

isReadyToCallExecute

public abstract boolean isReadyToCallExecute()

Indicates if all required input properties have been set. This abstract method is declared in the Command interface and must be implemented by the application programmer.

A typical implementation simply checks whether the required input properties are set:

      return (inputProperties != null)
 

Specified by:

isReadyToCallExecute in interface Command

Returns:

The value true if all required input properties are set and the command can be run.

performExecute

public abstract void performExecute()
                             throws java.lang.Exception

Runs the business logic that makes up the command. This abstract method is declared in the TargetableCommand interface and must be implemented by the application programmer. It is called by the executeCommand() method on the command target.

Specified by:

performExecute in interface TargetableCommand

Throws:

java.lang.Exception - Any exception that occurs in this method is thrown as an Exception or CommandException.

reset

public abstract void reset()

Sets the output properties to the values they had before the the execute method was run. This abstract method is declared in the Command interface and must be implemented by the application programmer.

A typical implementation just resets the output property variables:

      outputPropertyP = null;
      outputPropertyQ = 0;
 

Specified by:

reset in interface Command

setCommandTarget

public void setCommandTarget(CommandTarget commandTarget)

Sets the target object on the command. This implements the setCommandTarget() method declared in the TargetableCommand interface.

Specified by:

setCommandTarget in interface TargetableCommand

Parameters:

commandTarget - The target object, which locates the server where the command will run.

setCommandTargetName

public void setCommandTargetName(java.lang.String commandTargetName)

Sets the name of the target object on the command. This implements the setCommandTargetName() method declared in the TargetableCommand interface.

Specified by:

setCommandTargetName in interface TargetableCommand

Parameters:

commandTargetName - The fully qualified name of the Java class of the target object.

setHasOutputProperties

public final void setHasOutputProperties(boolean inProp)

Sets the hasOutputProperties class variable to indicate if the command has output properties that must be returned to the client.

Parameters:

inProp - A boolean indicating if there are output properties to be returned to the client.

setOutputProperties

public void setOutputProperties(TargetableCommand fromCommand)

Sets the return values on the command. This is the default implementation for the setOutputProperties() method in the TargetableCommand interface, but it can be overridden by the application programmer.

This implementation uses introspection to copy all instance variables, provided that they are non-private and non-package; that is, must be public or protected. This implementation does not copy the final, static or transient fields.

If this implementation is not acceptable, the programmer can override this method. A typical re-implementation does the following:

      this.outputPropertyA = fromCommand.outputPropertyA;
      this.outputPropertyB = fromCommand.outputPropertyB;
 

Specified by:

setOutputProperties in interface TargetableCommand

Parameters:

fromCommand - The command from which the output properties are copied.

setTargetPolicy

public static void setTargetPolicy(TargetPolicy targetPolicy)

Sets the target policy for the command.

Parameters:

targetPolicy - The target policy for the command.