Hi Experts,
In my landscape like below
SAP ECC --> SAP NW GW 7.41 ABAP stack --> SAP Web Dispatcher 7.41(Standalone DMZ).
all are above different physical servers and we are already successfully installed ECC and GW.
Here my questions is
1.Is it mandatory to select ABAP or Java Stack during the installation Web Dispatcher (Standalone) ?.
2.If it is mandatory for the above landscape, ABAP/Java or Dual-stack is required ?.
Can you please give suggestions on above questions 
.
Thanks,
Syam