Command registry framework in websphere commerce

Websphere commerce controller command and task commands are registered in command registry framework.

Interfacename
MyControllerCmd --> extends --> com.ibm.commerce.commands.ControllerCommand

Implementation class:
MyControllerCmdImpl --> extends --> com.ibm.commerce.commands.ControllerCommandImpl
and 
MyControllerCmdImpl implements MyControllerCmd
            
CommandFactory is a bean used for instantiating commands in websphere commerce.
Ex:
MyControllerCmd myCmd   = null;
myCmd  = (MyControllerCmd) CommandFactory.CreateCommand(com.ibm.commerce.myCommands.MyControllerCmd, getStoreId());
myCmd.setComandContext(getCommandContext());
myCmd.setRequestProperties(this.requestProperties);
myCmd.execute();
Where this.requestProperties is a TypedProperty object has all the request properties set.

There are 2 ways of defining implementation class for the inteface in websphere commerce:

1) defaultCommandClassName -The implementation class for the interface is defined in the interface by defaultCommandClassname
Ex:
public interface MyControllerCmd  extends ControllerCommand {
public Static final String defaultCommandClassName = com.ibm.commerce.myCommands.MyControllerCmdImpl;
}
      
2) CMDREG entry- Command Registry
 This table has following columns:
STORE_ID- 0 if the same implementation command  is used for all the stores.                    
INTERFACENAME- Name of the interface
CLASSNAME - implementation class name
DESCRIPTION - short description about the command
PROPERTIES - properties that are to be passed to command

CMDREG is preferred when different implementation classes are used for different stores. i.e the logic implementation changes based on the storeID

If suppose there is different entry in defaultCommandClassName and CMDREG table for the implementation class then Command Registry takes the precedence.

Simillarly for the taskcommands
Interfacename
myTaskCommand extends  --> com.ibm.commerce.commands.TaskCommand

Implementation class:
myTaskCommandImpl extends --> com.ibm.commerce.commands.TaskCommandImpl
and 
myTaskCommandImpl implements myTaskCommand

Imp Points:

• A controller command and task command both can be called from a controller command.
• A task command can call a taskcommand and even controller command.
• Both task command and controller command can have entry in CMDREG table.

Differences between controller command and task command:

Controller Command	Task Command
This is the entry point for fulfilling any request	This contains a part f business logic to be executed
This has struts entry	This cannot have an entry in struts file
Access Control policy (ACP) is enabled by default	ACP is not enabled
It has a viewname entry for redirecting the flow to the viewname after successful execution	It does not have viewname, the control is returned back to the called command.
Can be called from JSP	Cannot be called from JSP