I did search for this question before posting it here but still no success. I do see there are certain discussions about the lack of this 'necessary' API but they were raised quite long ago (about 1 year) so I am wondering if it is now available or there is an alternate/tricky way to do this?

Is it all about using 'filters'? As for transactions which are included into blocks, using filter will be useful but for the pending transactions, it will be much trickier (and the system performance will hurt) since all I can get is a list of pending transactions and I will have to iterate through this list to see which transaction belongs to which address to see if it is the one that I'm looking for.

Any advice or suggestions/recommendation in this case?

Thank you in advance!