Webdispatcher Communicating with SAP CRM Server behiind the DMZ

[Former Member]

Hi Experts,

Please provide your inputs for the communication scenario as mentioned below.

We have a external application hosted in Cloud and which needs to communicate with the CRM server which is Located behind the DMZ(De-militerised Zone) which has no Internet connectivity. Hence a Webdispatcher is placed in between the CRM system and the Client Machines which is trying to access the application. The request goes through the Webdispatcher and reaches the CRM server. The Webdipatcher serves to carry the request from the client machine to the other end where the CRM server is located , which is behind the DMZ. How is an Outbound communication possible. Say a webrequest from CRM server has to reach back to the Client. Please suggest what is the best possible way to communicate back via webdispatcher without using a reverse proxy. Kindly suggest !

[Former Member]

So here the reponse is comming back to the USER who is trying to send/recieve request via dispatcher to the CRM server behind the DMZ, but the same has to be updated in XCOT which is in "Cloud"... so i need a reverse proxy to push the request or a webservice to update/sync the information which is comming via dispatcher to the Internet Cloud (Xcot application).

[Former Member]

Thanks for the Reply Markus. I apprciate your timely help.

We have implemented SAP webdispathcer and now we want to implement reverse proxy. But SAP Webdispathcer does not work as a perfect reverse proxy. IISPROXY is no more supported as a reverse proxy as per the note 886214.

http://help.sap.com/saphelp_nw04/helpdata/en/e9/3bb7f8f6ea4e938ef0b9687cbb6c14/frameset.htm

under section "structure of the web dispatcher" it reads: "The response from the application server does not pass via the Web dispatcher again to the client u2013 it goes direct to the client (via a proxy, if the network is configured with one)."

Therefore it cannot be used as a full reverse proxy.

But for a full fledged reverse proxy you need to use SAP Webdispatcher with SPNego or any 3rd party reverse proxy server. Please refer SAP notes 886214 - End of Maintenance of IisProxy.

I have gone through many blogs and there is no exact blog which can suggest a perfect reverse proxy. The organisations who want to implement very high security they have an option to go with SPNego or a perfect 3rd party reverse proxy. We do not want to go with SPNego, but we prefer a 3rd party reverse proxy in a windows environment ... still searching for one such proxy and how it can be implemented in this scenario... where the request from our prduct X-COT which is in cloud, a webservice has to go via SAPwebdispatcher and reach SAP CRM server and bring back the update via SAPWebdispacther to the x-CON in cloud and update it. A better word to use other than Update is SYNC. From CRM server a calender update is not getting updated in XCOT via dispatcher. for that reason 3rd party reverse proxy is required, we are only using webdisp for masking the URL for security reasons and not for loadbalancing(which is the webdispatchers actual role). Kindly appriciate your valuble inputs.

Thanks and Regards,

Syed Subahan

[Former Member]

Hello Experts,

The request hits the DMZ system (proxy service / SAP web dispatcher), then it checks for the URL mapping of https://server01.companyname.com:8000/* and forwards through the firewall to the AS Server and responds back to the user in the same path. How does the reverse communication happen back to the client via the firewalls and the DMZ, how it is triggered back, please let me know in detail from node to node. Kindly. Thanks.

[markus_doehr2]

> How does the reverse communication happen back to the client via the firewalls and the DMZ, how it is triggered back, please let me know in detail from node to node. Kindly. Thanks.

You just answered your question yourself:

> ... forwards through the firewall to the AS Server and responds back to the user in the same path.

Markus