Friday, May 26, 2017

Connecting to on-premise IBM DB2 instances

Check out the following link to see the complete port list for connecting to an IBM DB2 database instance: http://www-01.ibm.com/support/docview.wss?uid=nas8N1019667

Of particular note, you'll want the "Database Access" port and the "DRDA" port, the latter seemingly used by OLEDB drivers.
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Getting table column metadata in IBM DB2 v7.2

So here's a useful little snippet for getting column metadata for tables in IBM DB2 7.2 :

SELECT * FROM sysibm.columns WHERE TABLE_SCHEMA = 'my_schema_name' AND TABLE_NAME = 'my_table_name'
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Tuesday, May 16, 2017

Unexpected ArgumentNullException when returning from a WCF operation call

I've recently run into a problem executing WCF calls to one of my services. I suspect that it has to do with a change to one of the Service Contracts, but I haven't been able to confirm this. I get the stack trace similar to the following:

System.ArgumentNullException:
   at System.Runtime.AsyncResult.End (System.ServiceModel.Internals, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35)
   at System.ServiceModel.Channels.ServiceChannel+SendAsyncResult.End (System.ServiceModel, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.ServiceModel.Channels.ServiceChannel.EndCall (System.ServiceModel, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.ServiceModel.Channels.ServiceChannelProxy+TaskCreator+<>c__DisplayClass7_0`1.<CreateGenericTask>b__0 (System.ServiceModel, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.Threading.Tasks.TaskFactory`1.FromAsyncCoreLogic (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at MyCompanyCanonical.Util.ServiceModelClient.ChannelFactoryExtensions+<UsingResultAsync>d__3`2.MoveNext (MyCompanyCanonical.Util.ServiceModelClient, Version=1.2.1716.1, Culture=neutral, PublicKeyToken=null)
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at MyCompanyCanonical.Data.CostCodeRepository+<RelayCostCodesAsync>d__11.MoveNext (MyCompanyCanonical.Data, Version=1.2.1716.1, Culture=neutral, PublicKeyToken=null)
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at MyCompanyCanonical.Service.Controllers.CostCodeController+<RelayCostCodesAsync>d__10.MoveNext (MyCompanyCanonical.Service, Version=1.2.1716.1, Culture=neutral, PublicKeyToken=null)
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.Threading.Tasks.TaskHelpersExtensions+<CastToObject>d__3`1.MoveNext (System.Web.Http, Version=5.2.2.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35)
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.Web.Http.Controllers.ApiControllerActionInvoker+<InvokeActionAsyncCore>d__0.MoveNext (System.Web.Http, Version=5.2.2.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35)
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.Web.Http.Filters.ActionFilterAttribute+<CallOnActionExecutedAsync>d__5.MoveNext (System.Web.Http, Version=5.2.2.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35)
   at System.Web.Http.Filters.ActionFilterAttribute+<CallOnActionExecutedAsync>d__5.MoveNext (System.Web.Http, Version=5.2.2.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35)
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.Web.Http.Filters.ActionFilterAttribute+<ExecuteActionFilterAsyncCore>d__0.MoveNext (System.Web.Http, Version=5.2.2.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35)
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.Web.Http.Controllers.ActionFilterResult+<ExecuteAsync>d__2.MoveNext (System.Web.Http, Version=5.2.2.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35)
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.Web.Http.Filters.AuthorizationFilterAttribute+<ExecuteAuthorizationFilterAsyncCore>d__2.MoveNext (System.Web.Http, Version=5.2.2.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35)
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.Web.Http.Filters.AuthorizationFilterAttribute+<ExecuteAuthorizationFilterAsyncCore>d__2.MoveNext (System.Web.Http, Version=5.2.2.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35)
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
   at System.Web.Http.Controllers.ExceptionFilterResult+<ExecuteAsync>d__0.MoveNext (System.Web.Http, Version=5.2.2.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35)


The problem turned out to be the Microsoft.ApplicationInsights.Wcf package that I'm using (v0.27 at the time of this writing). There's a problem with the WcfDependencyTelemetryInitializer module that slowly builds up over time and then suddenly starts tanking your requests. This thing is a land mine.
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