Inconsistent behavior when executing New-WebServiceProxy in a loop - wcf

Question

I'm having a problem with a powershell script that I wrote to call a method on a WCF web service. The WCF service has a composite DataContract as its sole request parameter. We have recently modified the ServiceContract (by adding two new methods), but the new methods are not being called by the powershell script. Here is the original contract:
[ServiceContract]
public interface IFileSystemService {
[OperationContract]
HashFileResponse HashFile(HashFileRequest req);
[OperationContract]
void GenerateFiles(GenerateFilesRequest req);
}
And here is the new contract:
[ServiceContract]
public interface IFileSystemService {
[OperationContract]
HashFileResponse HashFile(HashFileRequest req);
[OperationContract]
void GenerateFiles(GenerateFilesRequest req);
[OperationContract]
ParseFilePathResponse ParseFilePath(ParseFilePathRequest req);
[OperationContract]
ArchiveParsedFileResponse ArchiveParsedFile(ArchiveParsedFileRequest req);
}
The GenerateFiles method is the one being called by the PowerShell script. We have not modified the GenerateFilesRequest DataContract at all, which is defined below:
[DataContract]
public class GenerateFilesRequest : BaseRequest {
[DataMember(IsRequired = true)]
public int Id { get; set; }
}
Baserequest is currently an empty class for future use (all our request data contracts use it):
[DataContract]
public abstract class BaseRequest {
}
Calling this method works consistently via other means; SoapUI, Fiddler and via WCF contracts defined throughout the application.
After adding the two new methods, our integration tests are failing due to the fact the powershell script fails to call the GenerateFiles method consistently within a loop (see error output).
When I initially wrote this script, I was having a similar issue running it (though it either consistently broke, or consistently worked) but I managed to get the service calls working by adding the -Namespace and -Class arguments to the New-WebServiceProxy cmdlet.
Context: We are running a powershell script on a developer's machine, connecting to a WCF service hosted in IISExpress. All developers experience the same issues.
Here's the original script (preferred) before my recent modifications (this was working fine, but now most calls fail):
$sqlServer=$args[0]
function CallFSS($Id) {
$uri = "http://localhost:1234/FileSystemService.svc?wsdl"
$srv = New-WebServiceProxy -Uri $uri -Namespace fssNS -Class fssClass
$req = [fssNS.GenerateFilesRequest](New-Object fssNS.GenerateFilesRequest)
$req.Id= $Id
$response = $srv.GenerateFiles($req)
}
$SqlConnection = New-Object System.Data.SqlClient.SqlConnection
$SqlConnection.ConnectionString = "Server=" + $sqlServer + ";Database=MyDatabase;Integrated Security=True"
$SqlConnection.Open()
$SqlCmd = New-Object System.Data.SqlClient.SqlCommand
$SqlCmd.CommandText = "select Id FROM MyTable WHERE Status = 2"
$SqlCmd.Connection = $SqlConnection
$sqlResult = $SqlCmd.ExecuteReader()
while ($sqlResult.Read()) {
$Id = $sqlResult.GetInt32(0)
Write-Host Generating files for Id $Id
CallFSS $Id
}
$SqlCmd.Dispose()
$SqlConnection.Dispose()
$SqlConnection.Close()
Here is an excerpt of the output from the script. As you can see, this is vastly inconsistent (Lines marked like this succeed):
Generating files for Id 1
Cannot convert argument "req", with value: "fssNS.GenerateFilesRequest", for "GenerateFiles" to type "fssNS.GenerateFilesRequest": "Cannot convert the "fssNS.GenerateFilesRequest" value of type "fssNS.GenerateFilesRequest" to type "fssNS.GenerateFilesRequest"." At C:\SolutionPath\GENERATE_FILES.ps1:23 char:2
+ $response = $srv.GenerateFiles($req)
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], MethodException
+ FullyQualifiedErrorId : MethodArgumentConversionInvalidCastArgument
Generating files for Id 2
Cannot convert argument "req", with value: "fssNS.GenerateFilesRequest", for "GenerateFiles" to type "fssNS.GenerateFilesRequest": "Cannot convert the "fssNS.GenerateFilesRequest" value of type "fssNS.GenerateFilesRequest" to type "fssNS.GenerateFilesRequest"." At C:\SolutionPath\GENERATE_FILES.ps1:23 char:2
+ $response = $srv.GenerateFiles($req)
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], MethodException
+ FullyQualifiedErrorId : MethodArgumentConversionInvalidCastArgument
**Generating files for Id 3**
Generating files for Id 4
Cannot convert argument "req", with value: "fssNS.GenerateFilesRequest", for "GenerateFiles" to type "fssNS.GenerateFilesRequest": "Cannot convert the "fssNS.GenerateFilesRequest" value of type "fssNS.GenerateFilesRequest" to type "fssNS.GenerateFilesRequest"." At C:\SolutionPath\GENERATE_FILES.ps1:23 char:2
+ $response = $srv.GenerateFiles($req)
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], MethodException
+ FullyQualifiedErrorId : MethodArgumentConversionInvalidCastArgument Generating files for Id 8 Cannot convert argument "req", with value: "fssNS.GenerateFilesRequest", for "GenerateFiles" to type "fssNS.GenerateFilesRequest": "Cannot convert the "fssNS.GenerateFilesRequest" value of type "fssNS.GenerateFilesRequest" to type "fssNS.GenerateFilesRequest"." At C:\SolutionPath\GENERATE_FILES.ps1:23 char:2
+ $response = $srv.GenerateFiles($req)
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], MethodException
+ FullyQualifiedErrorId : MethodArgumentConversionInvalidCastArgument
**Generating files for Id 9**
**Generating files for Id 10**
**Generating files for Id 11**
Generating files for Id 12
Cannot convert argument "req", with value: "fssNS.GenerateFilesRequest", for "GenerateFiles" to type "fssNS.GenerateFilesRequest": "Cannot convert the "fssNS.GenerateFilesRequest" value of type "fssNS.GenerateFilesRequest" to type "fssNS.GenerateFilesRequest"." At C:\SolutionPath\GENERATE_FILES.ps1:23 char:2
+ $response = $srv.GenerateFiles($req)
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], MethodException
+ FullyQualifiedErrorId : MethodArgumentConversionInvalidCastArgument
Sometimes, most calls pass, and only the odd-one fails.
Here's another version of the script, which uses the auto-generated namespaces from New-WebServiceProxy:
$sqlServer=$args[0]
function CallFSS($Id) {
$uri = "http://localhost:1234/FileSystemService.svc?wsdl"
$srv = New-WebServiceProxy -Uri $uri
$type = $srv.GetType().Namespace
$datatype = ($type + '.GenerateFilesRequest')
$req = New-Object($datatype)
$req.Id = $Id
$response = $srv.GenerateFiles($req)
}
$SqlConnection = New-Object System.Data.SqlClient.SqlConnection
$SqlConnection.ConnectionString = "Server=" + $sqlServer + ";Database=MyDatabase;Integrated Security=True"
$SqlConnection.Open()
$SqlCmd = New-Object System.Data.SqlClient.SqlCommand
$SqlCmd.CommandText = "select Id FROM MyTable WHERE Status = 2"
$SqlCmd.Connection = $SqlConnection
$sqlResult = $SqlCmd.ExecuteReader()
while ($sqlResult.Read()) {
$Id = $sqlResult.GetInt32(0)
Write-Host Generating files for Id $Id
CallFSS $Id
}
$SqlCmd.Dispose()
$SqlConnection.Dispose()
$SqlConnection.Close()
Again, the results are inconsistent, though the error I get now relates to the auto-generated namespace:
**Generating files for Id 1**
**Generating files for Id 2**
Generating files for Id 3
Cannot convert argument "req", with value: "Microsoft.PowerShell.Commands.NewWebserviceProxy.AutogeneratedTypes.WebServiceProxy3234_FileSystemService_svc_wsdl.GenerateFilesRequest", for "GenerateFiles" to type "Microsoft.PowerShell.Commands.NewWebserviceProxy.AutogeneratedTypes.WebServiceProxy3234_FileSystemService_svc_wsdl.GenerateFilesRequest": "Cannot convert the "Microsoft.PowerShell.Commands.NewWebserviceProxy.AutogeneratedTypes.WebServiceProxy3234_FileSystemService_svc_wsdl.GenerateFilesRequest" value of type "Microsoft.PowerShell.Commands.NewWebserviceProxy.AutogeneratedTypes.WebServiceProxy3234_FileSystemService_svc_wsdl.GenerateFilesRequest" to type "Microsoft.PowerShell.Commands.NewWebserviceProxy.AutogeneratedTypes.WebServiceProxy3234_FileSystemService_svc_wsdl.GenerateFilesRequest"." At C:\SolutionPath\GENERATE_FILES.ps1:23 char:2
+ $response = $srv.GenerateFiles($req)
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], MethodException
+ FullyQualifiedErrorId : MethodArgumentConversionInvalidCastArgument
Generating files for Id 4
Cannot convert argument "req", with value: "Microsoft.PowerShell.Commands.NewWebserviceProxy.AutogeneratedTypes.WebServiceProxy3234_FileSystemService_svc_wsdl.GenerateFilesRequest", for "GenerateFiles" to type "Microsoft.PowerShell.Commands.NewWebserviceProxy.AutogeneratedTypes.WebServiceProxy3234_FileSystemService_svc_wsdl.GenerateFilesRequest": "Cannot convert the "Microsoft.PowerShell.Commands.NewWebserviceProxy.AutogeneratedTypes.WebServiceProxy3234_FileSystemService_svc_wsdl.GenerateFilesRequest" value of type "Microsoft.PowerShell.Commands.NewWebserviceProxy.AutogeneratedTypes.WebServiceProxy3234_FileSystemService_svc_wsdl.GenerateFilesRequest" to type "Microsoft.PowerShell.Commands.NewWebserviceProxy.AutogeneratedTypes.WebServiceProxy3234_FileSystemService_svc_wsdl.GenerateFilesRequest"." At C:\SolutionPath\GENERATE_FILES.ps1:23 char:2
+ $response = $srv.GenerateFiles($req)
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], MethodException
+ FullyQualifiedErrorId : MethodArgumentConversionInvalidCastArgument
+ FullyQualifiedErrorId : MethodArgumentConversionInvalidCastArgument
Etc... execution is different every time.
I dearly hope this is something I'm doing wrong / misunderstanding as I am about to entirely give up on PowerShell. Is this maybe a caching issue? Any help would be greatly appreciated.

Answer 1

Ok, I found something :)
I added an output for the GenerateFiles method definition within the CallFSS function:
$srv | gm -Name GenerateFiles | select -ExpandProperty Definition
Foreach successful request, the output was
void GenerateFiles(fssNS.GenerateFilesRequest req)
The definition was different if I encountered an error:
void GenerateFiles(fssNS.GenerateFilesRequest, oehlvn0y,
Version=0.0.0.0, Culture=neutral, PublicKeyToken=null req)
So if you create the object using the full qualified name, it should work:
function CallFSS($Id)
{
$uri = "http://localhost:11662/Service1.svc?wsdl"
$srv = New-WebServiceProxy -Uri $uri -Namespace fssNS -Class fssClass
# Get the definition of the GenerateFiles method
$definition = $srv | gm -Name GenerateFiles | select -ExpandProperty Definition
# Extract the full qualified type name of the first parameter
$paramType = [regex]::Match($definition, 'GenerateFiles\((.*)\s\w+').Groups[1].Value
$bar = new-object $paramType
$bar.Id = $Id
$response = $srv.GenerateFiles($bar)
}
Note: This solution only works for methods with one parameter due to the regex. However, here is an implementation I would recommend:
function Invoke-FSS # Invoke is a valid Verb (see Get-Verb)
{
[CmdletBinding()]
Param
(
[Parameter(Mandatory=$true,ValueFromPipeline=$true,Position=0)]
[int]$Id
)
Begin
{
$uri = "http://localhost:11662/Service1.svc?wsdl"
$srv = New-WebServiceProxy -Uri $uri -Namespace fssNS -Class fssClass
# Get the definition of the GenerateFiles method
$definition = $srv | gm -Name GenerateFiles | select -ExpandProperty Definition
# Extract the full qualified type name of the first parameter
$paramType = [regex]::Match($definition, 'GenerateFiles\((.*)\s\w+').Groups[1].Value
}
Process
{
$bar = new-object $paramType
$bar.Id = $Id
$response = $srv.GenerateFiles($bar)
}
End
{
$srv.Dispose()
}
}
In your example, you would invoke the method by piping the ids to the Invoke-FFS method:
$ids = #()
while ($sqlResult.Read()) {
$ids += $sqlResult.GetInt32(0)
}
$ids | Invoke-FSS
The Begin{} block gets called only once (to initialize your proxy) and the Process{} block gets called for each item in $ids. Finally, the End{} block gets called once at the end to dispose the proxy gracefully.