Cannot get the BizTalk ExposeWebService sample to run on Windows XP

I had problems getting the BizTalk 2006 R2 ExposeWebService sample to run on my Windows XP machine. The published orchestration threw a SOAPException. The event log said

 

An attempt to connect to "BizTalkMgmtDb" SQL Server database on server "SE-890652" failed. Error: "Cannot open database "BizTalkMgmtDb" requested by the login. The login failed."

 

and

 

The Messaging Engine failed to register the adapter for "SOAP" for the receive location "/ExposeWebService_Proxy/Microsoft_Samples_BizTalk_ExposeWebService_ProcessClientRequest_SOAPPort.asmx". Please verify that the receive location exists, and that the isolated adapter runs under an account that has access to the BizTalk databases.

 

Clear as a cucumber. You need to add the account that the isolated adapter runs under to the BizTalk Isolated Host Users group. But which account? In Windows Server 2003 (IIS 6), you can configure the account the application pool is using, as pointed out in the documentation (ms-help://MS.BTS.2006/BTS06CoreDocs/html/b6d2377b-5a8c-4f1c-8d01-75d3f34bef6a.htm). But Windows XP (IIS 5) does not have this feature. It turns out it is the local ASPNET account that has to be added to the BizTalk Isolated Host Users group. Run IISReset before trying again.