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.

Setting Up a Test Reverse Proxy/SSL Accelerator Environment (or for that matter, a budget production one)

In a previous post I talked about dealing with WCF services behind an F5 BIG-IP box (http://www.f5.com/products/big-ip/) that provides load balancing and SSL offloading.  I’ve actually found and developed solutions to the problems but needed to be able to properly test them.
Given that, according to our operations people, BIG-IP boxes start at 5 figures and rapidly go up, they seemed unwilling to purchase one for me.  Additionally, for security issues, and to remain in compliance with our SAS-70, I don’t have access to our production environment for testing.

Execute-Remotely

One of the really powerful features of PowerShell is the ability to run commands remotely.  I used this when I wanted to loop through my test servers from the build machine and run my MSI installs.

The following script loops through an array of machines and returns a list of .log files under the C:\Windows folder.  One thing to note.  The remote session doesn't have access to any of the local script variables, so we pass them as parameters using the -Args argument of the Invoke-Command cmdlet, receiving them using the param statement inside the remote script block.

    $AgentServers = @("MYSERVER1", "MYSERVER2");
   
    ForEach ($AgentServer in $AgentServers) {
        $Session = New-PSSession -ComputerName $AgentServer;
        $FilePattern = "*.log";
        $Arguments = $FilePattern
        Invoke-Command -Session $Session  -Args $Arguments -Script {
            param($FilePattern)

            Set-Location "C:\Windows"
            Get-ChildItem -Include $FilePattern -Recurse
        }
        Remove-PSSession -Session $Session
    }                                                                                                    

Now the first time you run the remote script above, it may well fail. Why? Because you forgot to enable remoting on the target machine. On each machine you want to run remote sessions on you’ll have to run:

Enable-PSRemoting

Note that you’ll have to start PowerShell as administrator to perform this.

Also take note that we’re killing each session using Remove-PSSession when we’re done with it as there is a 5 session limit on each remote server and it’s pretty easy to hit that if you forget to close out prior ones.

On that note, there’s a quick trick on clearing out all those orphaned sessions:

Get-PSSession | Remove-PSSession

Get-PSSession will return a list of all open session objects, piping them to Remove-PSSession which subsequently closes them out.

Run-Script

As I mentioned in an earlier post, just like the DOS command line has batch files, PowerShell can run PowerShell script files.  These have the .PS1 extension.

So go ahead, throw a bunch of PowerShell commands together into a .PS1 file in NotePad and save it.  Next, navigate to the folder you saved it to and double-click on it.  Awesome, you just ran your first PowerShell script!  What do you mean it didn’t run?  It came up in NotePad?

Oh yeah.  By default, for security reasons, double-clicking on a PowerShell script doesn’t run it.  To do that you have a couple of options.  First is to open up PowerShell and run the script from PowerShell's command line.  To do that you simply  type:

C:\MyScripts\MyCoolScript.ps1

If your current folder is already C:\MyScripts you’ll type:

.\MyCoolScript.ps1

Note that we prefaced the script file with “.\”.  Without that, PowerShell thinks it’s a built-in command and yells that it doesn’t recognize it.

OK, you’ve typed it in, hit enter and away it goes, no?  Except that all you see is:

File C:\MyScripts\MyCoolScript.ps1 cannot be loaded because the execution of scripts is disabled on this system. Please see "get-help about_signing" for more details.
At line:1 char:11
+ .\test.ps1 <<<<
    + CategoryInfo          : NotSpecified: (:) [], PSSecurityException
    + FullyQualifiedErrorId : RuntimeException

$%!#$%!^&*#…OK, ok, breath…again…deep breath…Yet another security “feature”.  With this one type at the command line:

Set-ExecutionPolicy RemoteSigned
Or
Set-ExecutionPolicy Unrestricted

You only need to run this once and it will allow you to run scripts.  When setting RemoteSigned, any local scripts will run as-is, but remote scripts will need to be digitally signed.  Like Enable-PSRemoting, you’ll need to open PowerShell as administrator.

But I’m not an administrator!  The execution policy is not a true security setting, it’s simply there to help prevent the inadvertent running of malicious scripts.  You can actually set the execution policy when you open PowerShell from the command line by using the –ExecutionPolicy argument, using the same RemoteSigned or Unrestricted value.  This will only set the execution policy for that session.

Note that when using the Set-ExectuionPolicy you can set the scope of the setting using the –Scope argument to be either the current process (-Scope Process, same as setting it on the command line), current User (-Scope CurrentUser) or the local machine (-Scope LocalMachine).  The default value is LocalMachine.