Portal 7.3 & Web Dynpro iView, both accessed from Internet via Web Dispatch

Question

Hi guru,
I'd like to know the best (or the correct) way to configure the FQDN and required DNS setting to allow user access ABAP Web Dynpro iview from internet.
My setup here is very typical:
One EP 7.3 in intranet, having "ep.internal.mycomp.com" as FQDN (given during installation)
One SAP ECC in intranet, having "erp.internal.mycomp.com" as SAPLOCALHOSTFULL parameter
One Web Dispatcher in DMZ, having "service.mycomp.com", and listen to 80 port (later added 8000 port for AS ABAP).
   User access my portal by using http://service.mycomp.com/irj, no problem.
But problem raised during access WD4A iview, here are my problem and questions:
[Problem]
At the beginning, we found that the WD4A iView can only be accessed in intranet, not from internet. Eventhough we register "service.mycomp.com" in public DNS. After some http level analysis, I was shock that the WD4A iview is provided directly by AS ABAP which running this WD4A, EP does not play a "relay" role. (Don't believe the URL bar in your IE, use Tamper Data or HTTP live to check the HTTP requests, you will get it). Since we DO NOT have "erp.internal.mycomp.com" in public DNS, so the iview cannot be displayed. But I DON'T want direct access to my ERP box.
I don't know a way to get rid of the "erp.mycomp.com" request generated by EP. So I tried to overcome the problem by leveraging the same Web Dispatcher used by EP. And I did make the WDisp -> ERP WD4A work using WDisp's FQDN (ie. service.mycomp.com:8000, also keep original service.mycomp.com:80 to EP), but the iview in EP does not use this FQDN. It use the SAPLOCALHOSTFULL parameter configured in backend ERP.  WDisp does not do any URL replacement for me.
[Question 1]
Is there any way to hide WD4A iview in EP (server to server communication only)?
[Question 2]
If I can only have "service.mycomp.com" entry in my public DNS, should I change the SAPLOCALHOSTFULL in ERP to "service.mycomp.com"?  I doubt  that it may cause a "loop" situation between WDisp and ERP ?
[Question 3]
Is it possible to access WD4A on ERP by two different FQDNs (one for public via WDisp, the other for internal access w/o WDisp) ? I know there is only one SAPLOCALHOSTFULL configuration.
Anyone have done such integration ? please share your configuraiton. Thanks

Answer 1

Hay Wei-Shang Ku,
Many thanks to your prompt reply of this very old post I tried to ask!
for the /sap/* redirect, think it required to use icm/HTTP/redirect_<xx> parametet in WDISP profile. And i did applied below too to make default WDISP URL go to /irj  (Portal login page).
icm/HTTP/redirect_0 = PREFIX=/,TO=/irj
so for "all request to /sap/* will go to ERP":
icm/HTTP/redirect_0 = PREFIX=/sap/*,TO=/???  (how do you set the TO value here?)
May i have your WDISP profile setting for reference? Did you make use of parameter wdisp/system_0?
And here is my overall setting:
we only have "service.mycomp.com" entry in public DNS.
1. "service.mycomp.com" is WDISP URL mapped to 1 public IP (we used default http 80 port)
2. we want user can access JPortal & also backend ERP via WebDynpro iView in JPortal via
   service.mycomp.com  (only port only)
3. ERP system profile:
    SAPLOCALHOSTFULL = <ERPHOSTNAME>.mycomp.com (not in public DNS)
    icm/server_port_0 = PROT=HTTP,PORT=80$$,TIMEOUT=3600,PROCTIMEOUT=3600
4. Portal:
    ABAP WebDynpro iView setting -
   System  = XXX (where XXX is alias of system iView)
  System iView setting -
    Logical System Name = ERPCLNTXXX
    ITS host = <ERPHOSTNAME>.mycomp.com:8000
Thanks again your information, have headache of this issue for long times....
Gary