is their any way to run loop in CREO ToolKit plugin so that i can send cmd from another app to CREO

typedef ProError (*ProTkdllFunction)( ProArgument* inputs,
ProArgument** outputs );
/*
Purpose: This is the function prototype for a function that can
be called from a external application using
ProToolkitTaskExecute().

Input Arguments:
inputs - ProArray of input arguments passed to the function.
The function must not free the array or any allocated
memory contained in this array.
Output Arguments:
outputs - ProArray of output arguments passed by the function.
The function must allocate memory for this array and
its contents.

Return Values:
Any return value - Passed as an output for ProToolkitTaskExecute().

extern ProError ProToolkitTaskExecute( ProToolkitDllHandle handle,
ProCharPath function_name,
ProArgument* input_arguments,
ProArgument** output_arguments,
ProError* function_return );
/*
Purpose: Causes Creo Parametric to execute a function in a DLL.
<b>Note:</b> The DLL must have been compiled in Pro/ENGINEER
Wildfire 1.0 or later.
<b>Note:</b>When done reading output_arguments, call
ProArgumentProarrayFree to free the data.

Input Arguments:
handle - The DLL handle.
function_name - The name of the function to call in the DLL. This
function must have been declared in the application
using the PRO_TK_DLL_EXPORT macro
and it must have a signature identical to the
signature declared for ProTKDllFunction.
input_arguments - A ProArray of input arguments passed to the DLL
function. This array should not contain any
ProValueData structures of type
PRO_VALUE_TYPE_POINTER.

Output Arguments:
output_arguments - A ProArray of output arguments outputted from the DLL
function. The called function should not populate
this array with any ProValueData structures of type
PRO_VALUE_TYPE_POINTER.
function_return - The return value of the DLL function.

Return Values:
PRO_TK_NO_ERROR - The DLL function execution succeeded.
PRO_TK_BAD_INPUTS - one or more of the arguments was invalid.
PRO_TK_BAD_CONTEXT - application handle is valid but the app was not
running.
PRO_TK_USER_ABORT - The DLL function returned something besides
PRO_TK_NO_ERROR. Check the value of function_return
for more details.
PRO_TK_E_NOT_FOUND - The function named could not be found and called.
PRO_TK_INVALID_PTR - One or more of the function argument arrays contain
value data of type PRO_VALUE_TYPE_POINTER. These
structures cannot be transferred.
*/

What mentioned by @RPN  is

'Task Based Application Libraries' - is a way to communicate between Creo auxiliary applications wrote in different API.

Not sure that is possible to send a cmd to creo from any external application.

Maybe you looking for "Asynchronous Mode". Check this chapter in Creo API documentation.