Scott Weinstein on .Net, Linq, PowerShell, WPF, and WCF

Powershell V2 has some great new features, in particular Add-Type and Remoting features are likely to be quite popular and work together without much issue. That said, there are edge cases which illustrate how the types returned from remoting calls. The following script demonstrates the issue

$csCode = @"
using System;
using System.Collections.Generic;
using System.Linq;
namespace Demo {
    public static class D
    {
        public static int Add(int a, int b)
        {
            return a + b;
        }
        public static int AddArray(int[] ints)
        {
            return ints.Sum();
        }
        public static int AddEnumerable(IEnumerable<object> ints)
        {
            return ints.Cast<int>().Sum();
        }
        public static int AddEnumerable(IEnumerable<int> ints)
        {
            return ints.Sum();
        }
    }
}
"@

Add-Type -TypeDefinition $csCode -Language CSharpVersion3
$oneRemote = Invoke-Command -ComputerName localhost  -ScriptBlock { return 1 }
$listRemote = Invoke-Command -ComputerName localhost  -ScriptBlock { return (1,2,3) }
$one = &{return 1}
if ($one -eq $oneRemote)
{
    Write-Host "1 == 1"
}

$v =  [Demo.D]::Add($one,$oneRemote)
Write-output "One + OneRemote = $v"  ; $v=$null
$v = [Demo.D]::AddArray(($one,$oneRemote))
Write-output "One + OneRemote via array =  $v" ; $v=$null

$v = [Demo.D]::AddArray($listRemote)
Write-output "One + OneRemote via remote array =  $v" ; $v=$null

$v = [Demo.D]::AddEnumerable((1,2,3,4))
Write-output "One + OneRemote via local IEnumerable =  $v" ; $v=$null

$v = [Demo.D]::AddEnumerable($listRemote)
Write-output "One + OneRemote via remote IEnumerable =  $v"; $v=$null



$oneRemote | Get-Member

The output from the above is

1 == 1
One + OneRemote = 2
One + OneRemote via array =  2
One + OneRemote via remote array =  6
One + OneRemote via local IEnumerable =  10 # so far as expected

 
Exception calling "AddEnumerable" with "1" argument(s): "Specified cast is not valid."
At typeDemo.ps1:49 char:29
+ $v = [Demo.D]::AddEnumerable <<<< ($listRemote)

   TypeName: System.Int32

Name               MemberType   Definition                                                                                                                                                                       
----               ----------   ----------                                                                                                                                                                       
CompareTo          Method       System.Int32 CompareTo(Object value)
Equals             Method       System.Boolean Equals(Object obj), System.Boolean Equals(Int32 obj)                                                                                                              
GetHashCode        Method       System.Int32 GetHashCode()                                                                                                                                                       
GetType            Method       System.Type GetType()                                                                                                                                                            
GetTypeCode        Method       System.TypeCode GetTypeCode()                                                                                                                                                    
ToString           Method       System.String ToString()
PSComputerName     NoteProperty System.String PSComputerName=localhost                                                                                                                                           
PSShowComputerName NoteProperty System.Boolean PSShowComputerName=True                                                                                                                                           
RunspaceId         NoteProperty System.Guid RunspaceId=e0dc5c05-c87d-41ad-afe0-16bc1b711f08                                                                                                                      

What’s happening under the covers is that the PowerShell reporting infrastructure is returning a PSObject. By inspecting the type via Get-Member you can see that it has some extra NoteProperties. To PowerShell and .Net methods that expect integers and arrays of integers, the object looks and behaves like it should. But if your Add-Types use a more LINQ style approach, which expects an IEnumerable<T>, the PowerShell type system doesn’t properly convert the adapted type to its native underlying type and runtime exceptions are the result.

There are some interesting sessions at the 2009 EntDevCon.

Three of particular interest to me are are

1. “Coral8 Engine Integrated with Microsoft Windows HPC Server 2008”  at 11 on Tuesday.

I had a chance to see some of the early bits, and for anyone interesting in streaming data with high computations needs, this promises to be well worth your time. In a future post I’ll talk about how this technology can be used.

Additionally, some co-workers at Lab49 will be presenting on Wednesday:

2. Marc Jacobs and Citi on “Agile Development using Low-Fidelity Prototypes, Expression Blend and SketchFlow:A Case Study”

3. Daniel Simon on “Patterns and practices:composite development for WPF and Silverlight using Composite Application Guidance (a.k.a. Prism 2.0)”

And if I have time, I might have a few hours at the Lab49 booth, stop by to say hi.

The PowerShell team has a short post on using V2 cmdlets to Monitor performance counters.

Building on that, and the prior work with the PoShAdapter, here’s a sample with Coral8 and PowerShell to alert you via SMS when the rolling 30 seconds average CPU hits a threshold.

create VARIABLE float CPUThreashold  = 70; 
create OUTPUT STREAM fakeout SCHEMA (x string);
CREATE SCHEMA CPUSchema (cpu FLOAT);
create INPUT STREAM inCPU SCHEMA CPUSchema;
create OUTPUT STREAM highCPU SCHEMA CPUSchema;
create local STREAM avgCPU SCHEMA CPUSchema;

ATTACH OUTPUT ADAPTER smsAdapter TYPE PoShAdapter TO STREAM highCPU
PROPERTIES
    BEGINBLOCK  = [[ 
    Add-Type -AssemblyName System.Security   
    Add-Type -Path "C:\Program Files\Coral8\Server\bin\GmailHelper.dll" 
    $pass = ".."
    ]],
PROCESSBlock     = [[
 foreach ($cpuSpike in $input)
 {
  $m = "CPU spike at {0:0.00}" -f $cpuSpike['cpu']
  [RC.Gmail.GmailMessage]::SendFromGmail("user", $pass,"6465555555@tmomail.net", 
   "Via Powershell/Coral8",$m)
 }
]];

ATTACH OUTPUT ADAPTER CPUAdapter TYPE PoShAdapter TO STREAM fakeout
PROPERTIES
    RESULTSSTREAM = "ccl://localhost:6789/Stream/Default/MonitorCPU/inCPU",
    INPUTBLOCK    = [[
Get-Counter '\Processor(*)\% Processor Time'    |
    select -expand CounterSamples               |
        ? { $_.InstanceName -eq "_total" }      | 
            % { ,,($_.CookedValue,0) } # 
]];

INSERT into avgCPU
select avg(cpu)  
from inCPU 
keep 30 SECONDS 
OUTPUT EVERY 30 SECONDS;

INSERT into highCPU 
select cpu 
from avgCPU 
WHERE cpu > CPUThreashold;

Yields:

*I lowered the threshold for testing
** Yes, I should check my voice mail

The system I helped build at my previous job gets a nice write-up in Wall Street & Technology:

Citi Taps CEP for Analyzing Equity Data

I’m sure Marc, Hanno and the rest of the team are pleased.

Congrats guys!

I’ve updated the PowerShell Coral8 adapter so it can be used to receive input. Rather than demonstrate input from a database or an RSS stream, both of which can are supported by the native Coral8 adapters, I have a demo with WMI events. In this case allowing us to monitor process creation across a network.

Using the same general template as before we have the following two script blocks

BeginBlock

$computers = &{$args} localhost ccs01 ccs02
$jobs = $computers | % `
 {
   Register-WmiEvent -Class Win32_ProcessStartTrace -ComputerName $_ ` 
   -Action  { `
            $res = @{}
            $res['ProcessName'] = $args[1].NewEvent.ProcessName
            $res['ComputerName'] = $args[0].scope.Path.Server
            return $res
        }
    }

InputBlock

while ($true) 
{
    Start-Sleep -Milliseconds 100
    foreach ($p in (Receive-Job $jobs))
    {
        # Input adapter doesn't support hashtables yet
        ,,($p['ProcessName'],$p['ComputerName']) 
    }
}

And the payoff

In the first post on integrating PowerShell and Coral8 I showed how to create a message sink. In C#ish pseudocode we did the following:

OutputStream<T>  =>  Action<T>

where the Action<T> was a PowerShell block to send a message via GMail.

Today the goal is to do a transform, something along the following

OutputStream<T>  =>  Func<T,T2> => InputStream<T2>

In this example, T will be a pair of stock symbols, T2 will be a pair stock symbols along with the correlation of their log normal closing prices for the past 10 days.

let’s get started.

CREATE SCHEMA           StockPairSchema( SecA STRING,SecB STRING );
CREATE SCHEMA           StockPairCorrelationSchema INHERITS from StockPairSchema (CORR  FLOAT) ;
CREATE OUTPUT   STREAM  StockPairs          SCHEMA StockPairSchema;
CREATE INPUT    STREAM  StockCorrelations   SCHEMA StockPairCorrelationSchema;
ATTACH OUTPUT ADAPTER PairstoCorrelationsFunc TYPE PoShAdapter TO STREAM StockPairs
PROPERTIES
RESULTSSTREAM = "ccl://localhost:6789/Stream/Default/TestC8/StockCorrelations",

The process block is very simple:

foreach ($t in $input)
{
    $a = Get-LogReturns $t["SecA"]
    $b = Get-LogReturns $t["SecB"]
    $c = [Demo.Stats]::Correlate($a, $b)
    ,,($t["SecA"],$t["SecB"],$c) #// double commas so the values are not flattened
}

The block path defines the Get-LogReturns and Correlate function, so naturally it’s a bit longer.
Get-LogReturns:

$wc = New-Object Net.WebClient    
function Get-LogReturns ($sec)
{
    $qry = "http://ichart.finance.yahoo.com/table.csv?s=$sec"
    $secAData = ConvertFrom-Csv $wc.DownloadString($qry) | select  -First 10 | % { $_.'Adj Close' }
    for ($i=0; $i -lt $secAData.Count-1; $i++) { [Math]::Log( $secAData[$i] / $secAData[$i+1] )  }
}

[Demo.Stats]::Correlate

$csCode = @"
using System;
using System.Collections.Generic;
using System.Linq;
namespace Demo 
{
    public static class Stats
    {
        private static IEnumerable<TResult> Zip<TFirst, TSecond, TResult>(IList<TFirst> first, 
				IList<TSecond> second, 
				Func<TFirst, TSecond, TResult> func)
        {
            for (int ii = 0; ii < Math.Min(first.Count(),second.Count()); ii++)
                yield return func(first[ii],second[ii]);
        }
        public static double Correlate(object[] s1,object[] s2)
        {
            return Correlate(s1.Cast<double>(), s2.Cast<double>());
        }
        public static double Correlate(IEnumerable<double> s1,IEnumerable<double> s2)
        {
            var sum1 = s1.Sum();
            var sum2 = s2.Sum();
            var sumSq1 = s1.Select(v=> v*v).Sum();
            var sumSq2 = s2.Select(v=> v*v).Sum();
            var pSum = Zip(s1.ToList(),s2.ToList(), ( a, b) => a*b).Sum();
            var len = s1.Count();
            var num = pSum - ((sum1 * sum2) / len);
            var denom = Math.Sqrt(((sumSq1 - (sum1 * sum1) / len) * (sumSq2 - (sum2 * sum2) / len)));
            return (denom == 0.0) ? 0 : num / denom;
        }
    }
}
"@
Add-Type -TypeDefinition $csCode -Language CSharpVersion3 -PassThru 

And in case you missed it, the correlate function isn't in PowerShell at all, but rather coded up via in-line C# code, compiled at the startup of the adaptor, and running in the Coral8 server process.

For certain types, PowerShell has automatic properties, by this I mean PowerShell is able to inspect the object and then expose properties where normally you would need to use a string indexer.

Like so:

$xbooks = [xml]"<Books><Book><Title>PowerShell in Action</Title></Book></Books>" 
$xbooks.Books.Book.Title

Similar functionality is available for COM, WMI, ADO.Net, and AD types. It’s one of the core features of PowerShell, and its simplicity and elegance makes even diehard UNIX types sit up and take notice.

But if you’re writing your own cmdlet, navigation provider, or are hosting PowerShell, and you wish to provide an adapter for your own type – you will quickly find that adapters and rest of the infrastructure for automatic properties are internal classes and unavailable to you.

The best option you have is something along the following:

public PSObject CreateCustomPSObject(MyType mytype )
{
    PSObject pso = new PSObject(mytype);
    foreach (string name in MyColumnNames)     
    { 
        string getter = String.Format("$this[\"{0}\"]", name); 
        string setter = String.Format("$this[\"{0}\"] = $value", name); 
        pso.Properties.Add(new PSScriptProperty(name,                                        InvokeCommand.NewScriptBlock(getter),                                InvokeCommand.NewScriptBlock(setter))); 
    
    } 
    return pso; 
}
WriteItemObject(CreateCustomPSObject(mytype));

This will work, but the output from get-member won’t be as clean as it is for a DataRow or other adapted types. Even worse, this option isn’t available at all for hosted scenarios as there no instance of CommandInvocationIntrinsics available from a Runspace or Pipleline.

A few days ago a thought crept into my head; wouldn’t it be nice if I could have a Coral8 in-process adapter to run PowerShell code? If it worked it could potentially be a “universal” adapter, limiting the need for custom one-off adapters.

Coral8, out-of-the-box, supports two different types of adapters. In-process adapters which must be written in C (enough said?), and out-of-process adapters which can be written in the language of your choice, but then have startup sequence, configuration, and deployment work associated with them.

Using the PoShAdapter I’ve been developing, let’s take a look at the adapter as a message sink. In this case a  “sent to Gmail” adapter.

CREATE SCHEMA TSchema ( toAddr STRING , subject string, message as string); 
CREATE OUTPUT STREAM outGmail SCHEMA TSchema; 
ATTACH OUTPUT ADAPTER PoShAdapter TYPE PoShAdapter  TO STREAM outGmail  PROPERTIES          
BEGINBLOCK  = [[   
    Add-Type -AssemblyName System.Security     
    Add-Type -Path "C:\Program Files\Coral8\Server\bin\GmailHelper.dll"   
    $encPassword = "AQQbRXQr…kg=="   
    $password =[Text.Encoding]::UTF8.GetString([Security.Cryptography.ProtectedData]::UnProtect([System.Convert]::FromBase64String($encPassword),$null,"CurrentUser"))
]],
PROCESS     = [[             
    foreach ($t in $input)             
    {                  
        [RC.Gmail.GmailMessage]::SendFromGmail("from.user", $password,
                       $t["toAddr"], $t["subject"], $t[“message”])
    }
    ]];

The posh adapter, like PowerShell scripts and functions have begin, process, and end blocks.

In the beginblock we load the assemblies for System.Security and GmailHelper, as well as decrypt the gmail password.

The process block will have as its $input set to a collection of the Coral8 tuples, so it simply loops through them sends out an email for each one. Because we the Runspace is kept for the lifetime of the adapter, context from the beginblock is available in the process block.

In later posts I’ll explore using the PoShAdapter to transform data (as in a select or map operator), and look into the possibility of using the adapter to listen for WMI or other system events.

Anyone who’s ever done office integration has come across a method definition like so:

object Run(object Macro, object Arg1, object Arg2, …, object Arg30);

if you're working in VB it’s not such an issue, and rumor has it that it’s that C# 4 will also solve the problem of code such as:

Run(“…”, Type.Missing, Type.Missing,/*28 more times*/ …, Type.Missing);

But for everyone else, you can avoid the extra typing with an extension method and dynamic lambda expressions. For example with:

    public static class OfficeHelpers
    {
        private static MemberInfo missingMemberInfo = typeof(Type).GetMembers().Where(mi => mi.Name == "Missing").Single();
        private static MethodInfo runMethodInfo = typeof(_Application).GetMethod("Run");
        private static ParameterExpression macroNameParamExp = Expression.Parameter(typeof(string), "macroName");
        private static ParameterExpression argsParamExp = Expression.Parameter(typeof(object[]), "args");

        public static object Run(this Application App, string macroName, params object[] args)
        {
            var argsExprs = GenerateArgs(runMethodInfo, macroName, args);
            var callExpr = Expression.Call(Expression.Constant(App), runMethodInfo, argsExprs);
            var paramExprs = new ParameterExpression[] { macroNameParamExp, argsParamExp };
            var lambda = Expression.Lambda>(callExpr, paramExprs);
            return lambda.Compile().Invoke(macroName, args);
        }

        private static IEnumerable<Expression> GenerateArgs(MethodInfo runfuncMI, string macroName, object[] args)
        {
            yield return macroNameParamExp;
            for (int ii = 0; ii < args.Length; ii++)
                yield return BinaryExpression.ArrayIndex(argsParamExp, Expression.Constant(ii, typeof(int)));
            for (int ii = 0; ii < runfuncMI.GetParameters().Length - args.Length - 1; ii++)
                yield return Expression.MakeMemberAccess(null, missingMemberInfo);
        }

a call to

OfficeHelpers.Run("…", arg1,arg2,arg3);

will generate and execute an expression like so:

(macroName, args) => RunFuncTest(macroName, args[0], args[1], args[2], Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing)

A few months ago, over the winter holiday, I put together a Linq provider for the Kdb+ database. The folks at KX systems have graciously provided a place to host the code, which you can find at https://code.kx.com/svn/contrib/sweinstein/linq2kdbplus. Use anonymous/anonymous for access.

As of now the list of the unimplemented items is considerably longer than implemented features.

What works

• Basic projections / Selects (map)
• Basic restrictions / Wheres (filter)
• code generation to create strongly typed representations of a Kdb database

Still remaining to implemented

• Joins
• Orderbys
• Grouping
• Aggregates and other functions/method calls
• Kdb+ columns with array types
• Code generation support for Kdb+ user functions

A few notes on the code

• run  SetupCodeGen.ps1 to have the correct paths placed in the registry

Feedback welcome.