MSTDC Error in clustered Environment in while interacting to DB Server from BizTalk server

Question

Hi All,
After completing all my required Biz-talk Integrations (All were related to WCF-Custom Adapter : SQL Binding), I deployed the same to the client environment. But, the same thing which worked for me in my development environment was giving some issues in
the deployed environment.
The main difference was, at client environment - The DB Server was clustered environment and the interaction was through the load balancer.
The first issue I encountered was, there was firewall blocking the access to the DB server from Biz Talk server. Then after enabling and opening the Port 1433, the issue got fixed and I was able to communicate with the DB Server.
After this, I was getting the error related to MSTDC. For this to work properly, in my BizTalk application Configuration, if i set the property for "UseAmbientTransaction" as false under "SqlBinding" for the WCF-Custom Send Port, it is
working as expected!
But, I heard from our Architects that the best approach is to set the property as "TRUE" for "UseAmbientTransaction" property.
So I set the property as true and done the below configurations.
1. Enabling Network DTC using "dcomcnfg.exe"
2. Adding and enabling Fire wall exception for DTC.
Even after making the above changes, I was getting the same error. Then after cross checking with DTCPing and DCTester on both local and deployed copy, i got the below difference.
1. Port 135 (RPC EPM) was opened in my local environment but it was having "Filtered" access at the deployed copy.
So my question is, after opening the above port, will it solve the issue?
Secondly, is there any security threat ter opening the above Port?
Any quick suggestion/solution is highly appreciated.
Thanks in Advance,
Anand

Answer 1

Hi Anand,
Performing operations on SQL Server using BizTalk Server always involves two resources—the adapter connecting to SQL Server and the BizTalk Message Box residing on SQL Server. Hence, all operations performed using BizTalk Server are performed within the
scope of an MSDTC transaction. So, to use the SQL adapter with BizTalk Server, you must always enable MSDTC. To enable the adapter to perform operations within the scope of an MSDTC transaction, you must configure MSDTC both on the computer running the SQL
adapter and SQL Server. Also, you must add MSDTC to the exceptions list of Windows Firewall. That is the reason why recommend setting for this binding property is
true; otherwise you might either experience message loss or duplicate messages, depending on whether you are performing inbound or outbound operations.
Exception is for operations where the adapter client does not write any data to the SQL Server database, such as a Select operation, you might not want the additional overhead of performing the operations inside a transaction. In such cases,
you can configure the SQL adapter to perform operations without a transactional context by setting the
UseAmbientTransaction binding property to false.
Just refer the link fo all the details:
Configure MSDTC on SQL Server and Adapter Client
Rachit
Rachit
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