COALESCE vs. ISNULL in T-SQL

A colleague of mine forwarded the following article along to me:

Deciding between COALESCE and ISNULL in SQL Server (http://www.mssqltips.com/sqlservertip/2689/deciding-between-coalesce-and-isnull-in-sql-server/)

I switched over from ISNULL to COALESCE a couple of years ago and haven’t looked back, primarily to standardize and avoid nested ISNULLs.  This article seems to affirm my thought that there are few disadvantages to COALESCE except in certain unusual circumstances.  It’s worth a quick read.

Tracing WCF Calls

I ran into an issue with one of my WCF services and was having the quite a time trying to track it down, especially since it was failing before it was getting to the actual service.  I came across a nice way of tracing the call all the way through the process.  Add the following section to your web.config file:

<system.diagnostics>
  <sources>
    <source name="System.ServiceModel"
            switchValue="Information, ActivityTracing"
            propagateActivity="true">
      <listeners>
        <add name="traceListener"
            type="System.Diagnostics.XmlWriterTraceListener"
            initializeData= "C:\Logs\Traces.svclog" />
      </listeners>
    </source>
  </sources>
</system.diagnostics>

This will create a trace file that you can open up in the Microsoft Service Trace Viewer.  You can read about the details here.

Quick note – Don’t forget to remove it when you’re done!

WCF Security Debugging Trick

Not infrequently, while deploying my WCF web services to various dev and QA environments I run into security issues, where for some reason I can’t get authenticated.  I recently found an article that (WCF: "An error occurred when verifying security for the message." and Service Security Audit) that talks about how to get more info on these errors logged in the application log using the following serviceSecurityAudit behavior:

<serviceSecurityAudit 
	auditLogLocation="Application"
	serviceAuthorizationAuditLevel="Failure"
	messageAuthenticationAuditLevel="Failure"
	suppressAuditFailure="true"/>

Text Files, ASCII, ANSI, Unicode and Code Pages

OK, so according to Joel Spolsky, I should have known this 7 or so years ago, but I’m only now dealing with multi-lingual text files so you’ll have to forgive me.  Anyway, this is a very instructive article on the encoding of text files:\

The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!)

C# Case-Insensitive Dictionary

Here’s a neat little feature I wasn’t aware of until recently.  You can make a .NET Dictionary object case-insensitive.  i.e. myDictionary[“ABC”] returns the same as myDictionary[“aBc”].  You can read more at:

C# Case-Insensitive Dictionary on Dot Net Perls (http://www.dotnetperls.com/case-insensitive-dictionary)

Returning Multiple Disparate Result Sets as XML From SQL Server Using FOR XML EXPLICIT

OK.  So I’m finally returning to a SQL Server topic.  The integration tool I’m working on does a great deal of processing of XML.  In some cases, a single XML document consists of multiple result sets.  I won’t get into the details of why we need this, but a good example of where you might use it is to return an Order object from a database for an edit form and additional return a list of Order Types to populate the Order Type drop down box.  In this case the XML might look like this:

<orderformdata>
    <orders>
        <order>
            <orderdate>1/1/2011</orderdate>
            <ordertypeid>1</ordertypeid>
            <orderamount>1000.00</orderamount>
        </order>
        <order>
            <orderdate>1/1/2011</orderdate>
            <ordertypeid>1</ordertypeid>
            <orderamount>1000.00</orderamount>
        </order>
    </orders>
    <references>
        <ordertypes>
            <ordertype id="1" name="Professional Services"/>
            <ordertype id="2" name="Product"/>
            <ordertype id="3" name="Support Contract"/>
        </ordertypes>
    </references>
</orderformdata>

Using SQL Servers FOR XML clause, it’s quite easy to output a result set as XML.  With the EXPLICIT directive you can have a great amount of control over how the XML is rendered.  However, the examples tend to show how to create XML from a single result set or nested records (say orders and order details).  So how to return the above?

Fun with WCF, WSDL & the F5 (Updated)

So this week we pushed out an early iteration of the latest version of our integration tool to a customer as a proof-of-concept for evaluation.  One of the features they were most interested in evaluating is the web service interface.  Our current customers interact with the existing version of the integration tool through FTP and a UI. 

Although the backend functionality is fairly stable, the web service layer itself is not that mature.  Not too big a deal as it’s a fairly thin wrapper over our existing service layer.  We created, tested and delivered a test .NET client that seemed to work fine and so were reasonably confident that there wouldn’t be too many hiccups.

Not so much.  We spent the better part of the day simply trying to get their tool to retrieve and understand our WSDL.  The good news is that we finally got it to work.