Setting SOAP, HTTP, and HTTP-based WCF Adapters Concurrent Connections

By default the SOAP, HTTP, and HTTP-based WCF adapters (and .NET in general) open only two concurrent HTTP connections from each BizTalk host instance to any specific destination server. For example, if you have a SOAP send port sending messages to http://www.contoso.com/SomeWebService.asmx, then by default each host instance running on each BizTalk Server will open only two concurrent HTTP connections to www.contoso.com, no matter how many messages need to be sent.

This setting conforms to the IETF RFC for the HTTP 1.1 specification, and although it is suitable for user scenarios, it is not optimized for high throughput server to server communications. The default setting effectively throttles outbound SOAP and HTTP calls to each destination server to two concurrent sends from each BizTalk Server host instance.

Increasing the Number of Concurrent Connections

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To increase the number of concurrent connections, you can modify the entry in the BizTalk Server configuration file, BTSNTSvc.exe.config (or BTSNTSvc64.exe.config for 64-bit hosts), on each computer running BizTalk Server. You can increase this for the specific servers being called. For information about modifying this entry in the BTSNTSvc.exe.config or BTSNTSvc64.exe.config file, see SOAP Adapter Configuration and Tuning Parameters (http://go.microsoft.com/fwlink/?LinkId=154197) in BizTalk Server 2009 Help.

The following is an example of the configuration for the maximum connections property:

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<configuration>
  <system.net>
    <connectionManagement>
      <add address="www.contoso.com" maxconnection="20" />
      <add address="*" maxconnection="10" />
    </connectionManagement>
  </system.net>
</configuration>

Note
Do not increase the value for the maxconnection parameter to such a large value that the Web server being called is overwhelmed with HTTP connections. Perform stress testing by sending requests to each destination Web server to determine a value for maxconnection that will provide good performance for SOAP and HTTP sends without overwhelming the target Web servers.