Andreas Lehmann

Be aware of the serializer when using AppFabric or Workflow Manager

2013-11-26T13:47:00Z

When you develop a custom activity for Workflow Foundation 4.x xamlx workflows think about the persistence of your arguments and context variables.
This are the “Persistence Best Practices” which MSDN recommends:
“A workflow can only be persisted if all of the data types used by the workflow are serializable. In addition, custom types used in persisted workflows must be serializable with NetDataContractSerializer in order to be persisted by SqlWorkflowInstanceStore.” (http://msdn.microsoft.com/en-us/library/ff729670%28v=vs.110%29.aspx)

But what is “serializable” in this context, what serializer is used for serialization?

Every time your workflow hit a persistence point (explicit or implicit [like a delay activity]) your context data will be serialized into your configured persistence store.
At one of our projects a workflow was hosted in Workflow Manager and we end up with a serialization exception for an Exception type (see damirs blog for details: http://developers.de/blogs/damir_dobric/archive/2012/11/16/serialization-of-exceptions-in-workflow-manager.aspx). On another project a workflow was hosted in AppFabric (IIS) and here we end up with a serialization exception at an XmlDocument typed argument of a custom activity. But we although use Exception as argument for a custom logging activity with no issues on serialization.

So I ask myself the question what serializer is used (if you have a link to an official documentation, please leave a comment). It cannot be the same serializer in AppFabric and Workflow Manager.

After some search on the web it seems to be that Workflow Manager uses (good old BizTalk proven) XmlSerializer to serialize persistence data (XmlDocument has a special handling here and Exception is not serializable with XmlSerializer). AppFabric (with SqlWorkflowInstanceStore for persistence) uses the NetDataContractSerializer (XmlDocument cannot be serialized but Exception works well).

So when you write custom activities make sure to check appropriate serialization for your arguments and context variables. Since you can host your xamlx workflow in Workflow Manager and AppFabric check that the types you are using can be serialized with both XmlSerializer and NetDataContractSerializer.

Here is some quick code to check serialization of your types (using one of the thousand console application on your dev machine ;)

static void S1(object x)

    var fs = new FileStream(@"c:\temp\text1.xml", FileMode.Create);

    var writer = XmlDictionaryWriter.CreateTextWriter(fs);

    var s = new NetDataContractSerializer();

    s.WriteObject(writer, x);

    writer.Close();

static void S2(object x)

    var fs = new FileStream(@"c:\temp\text2.xml", FileMode.Create);

    var writer = XmlDictionaryWriter.CreateTextWriter(fs);

    var s = new XmlSerializer(x.GetType());

    s.Serialize(writer, x);

    writer.Close();

How to manage local files on Windows 8.1 / RT

2013-10-24T13:49:00Z

Hi there, are you looking for a "metro"-style file manager?
There is one already built into windows 8.1, the SkyDrive app. Just switch from "SkyDrive" to "This PC" in the headline to access all your local files and folders.

Here you can do all the basic file operations like delete, copy, cut, rename...
Like some other features in Windows 8.1 sometimes hard to find ;-)

Windows Phone 7 Series CTP of the SDK available

2010-03-16T07:27:00Z

You can get your copy of the Windows Phone 7 Series SDK (CTP) at http://developer.windowsphone.com/windows-phone-7-series/.

Grab all your Silverlight knowledge and start developing apps for the new Windows Phone…

Slide Deck and Samples for Windows Mobile Widgets Session at Basta! 2010

2010-02-25T12:17:56Z

Here you can download the slides (here) and samples (here) I used for my session at Basta! 2010.

HowTo: Enable WCF Message Tracing

2009-11-12T19:14:23Z

In this post I will shortly describe how to enable and use WCF-Message-Tracing.

1. Add tracing to your web.config of the WCF-Service. I use WCF-Config-Editor for this task, so I don’t have to keep all this xml nodes and settings in mind.

When you have started the WCF Service Configuration Editor once a time in a Visual Studio session, you can use the context menu of the web.config file to open it.

2. In the WCF Config Editor you can enable the logging for the service messages (Usually when I wan to debug a service I enable everything I can get)

Make sure that the logging and tracing files are written to path that exists on the hosting environment (usually I enter only the filename without path so the log-files are written in the service directory)

3. After deploying your new configuration it is time to call your service and let the WCF write some traces…

4. After your service call it might be necessary to reset the application pool of the WCF service to flush the WCF log writer (sometimes log is not written when the call has ended). Normally I do this using iisreset command (one of my dev-favorite commands ;-) but you can although recycle the app-pool

5. Go and take a look at your log files.If you have chosen the same brute-force logging as I did on my screenshots you should see two log files created with the extension ’svclog’.

6. Give it a try and feel the pain open this file using notepad…

7. Now open the ‘Service Trace Viewer’ tool which you can find in "C:\Program Files\Microsoft SDKs\Windows\v6.0A\bin\SvcTraceViewer.exe" or "C:\Program Files\Microsoft SDKs\Windows\v7.0A\bin\NETFX 4.0 Tools\SvcTraceViewer.exe".Using Vista or 7 you just have to type ‘trace’ in the start search field and you will see the tool…

8. Just drag&drop both log-files in the tool. The Trace Viewer will do the linking between the trace- and log-file

9. Start analyzing your messages and find the annoying bug you are chasing for…

10. Important: Because tracing and logging has impact to the performance of the WCF-Service don’t forget to disable or at least reduce it (e.g. log only errors) when you are finished.

More information about logging and tracing in WCF you can find in the MSDN:

WCF Message Logging - http://msdn.microsoft.com/en-us/library/ms731859.aspx
WCF Tracing - http://msdn.microsoft.com/en-us/library/ms730342.aspx
Service Trace Viewer Tool - http://msdn.microsoft.com/en-us/library/ms732023.aspx

Set max upload size for IIS7 web applications

2009-06-24T11:52:32Z

If you want to set the maximum request size, e.g. to define the maximum size for file uploads, you can use the way described in this post:

http://developers.de/blogs/nadine_storandt/archive/2009/04/24/moss-set-max-upload-size-on-iis-7.aspx (thanks to Nadine)

This command line tool just adds a new node to the web.config file of the target application. This node is added to the <system.webServer> section:

        1: <security>

       2:     <requestFiltering>

       3:         <requestLimits maxAllowedContentLength="52428800" />

       4:     </requestFiltering>

       5: </security>

The value of the maxAllowedContentLength attribute is the number of bytes for the request.
If you want to allow 50 MB file upload this means 1024 x 1024 x 50 = 52428800

A simple implementation of config files for windows mobile

2009-05-26T13:06:00Z

Have you ever written a mobile application using .NET compact framework and tried to use config files? I think there are many scenarios where you want to have a configurable mobile application. So I can’t understand why Microsoft hasn’t implemented (even a subset of) the .NET application configuration handling in CF.
Here is a short implementation which gives you very basic configuration abilities in CF.

First I build a simple class for reading the configuration using the XmlDocument class. This class is designed to be static, so you can access the configuration without having to create an instance of the MobileConfiguration class.

public static class MobileConfiguration
{
    public static NameValueCollection Settings;
  
    static MobileConfiguration()
    {
        string appPath = Path.GetDirectoryName(Assembly.GetExecutingAssembly().GetName().CodeBase);
        string configFile = Path.Combine(appPath, "App.config");
  
        if (!File.Exists(configFile))
        {
            throw new FileNotFoundException(string.Format("Application configuration file '{0}' not found.", configFile));
        }
  
        XmlDocument xmlDocument = new XmlDocument();
        xmlDocument.Load(configFile);
        XmlNodeList nodeList = xmlDocument.GetElementsByTagName("appSettings");
        Settings = new NameValueCollection();
  
        foreach (XmlNode node in nodeList)
        {
            foreach (XmlNode key in node.ChildNodes)
            {
                Settings.Add(key.Attributes["key"].Value, key.Attributes["value"].Value);
            }
        }
    }
}

Now you just need to add an app.config to the root of your mobile application. You can do this by adding a new xml-document with the name “app.config” (or whatever name you would like). Don’t forget to set the Build Action of this file to “Contend” so that the file will be deployed to the mobile device.

Here is a sample App.config:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <appSettings>
    <add key="ServerName" value="myServer.MyDomain" />
    <add key="ServerPort" value="0815" />
    <add key="UserName" value="MyUser" />
    <add key="Password" value="MyPwd" />
  </appSettings>
</configuration>

The access to these settings in the mobile application is very easy:

...
string userName = MobileConfiguration.Settings["UserName"];
...

I know this is no solution for more complex scenarios and it can’t be compared with the power of ConfigSections in the “real” Framework, but with this solution it is possible to use simple configuration for windows mobile based applications.

Where the “c:\fakepath” comes from…

2009-05-15T13:01:48Z

Thanks to new security features in IE 8 the file upload will not report the real file path to the control unless you add the page to the trusted site collection of the IE. Instead the “c:\fakepath” is shown to the JavaScript that handles the file upload information.

So don’t try to find the error in your implementation :-)

How to use Entity Framework to query string values with filter conditions

2009-04-08T12:57:33Z

Have you ever tried to filter a LINQ statement by string values. E.g. you want to get all persons where the name starts with letters from ‘A’ to ‘Z’. In this post I will show you how to build a query like this.

My first approach was to do a simple <= operation like I do in SQL. But this results in an exception: “Operator '<=' cannot be applied to operands of type 'string' and 'string'”. OK, I remember, we are in the .NET world. So I tried the .CompareTo() method of string. And it seems to work. So my LINQ statement would be:

        1: string valueMin = "A";

       2: string valueMax = "Z";

       3:  

       4: var x = from p in context.TPerson

       5:         where p.Name.CompareTo(valueMin) >= 0 &&

       6:               p.Name.CompareTo(valueMax) <= 0

       7:         select p;

Imagine a list of people: “Anton”, “Bill”, “Hans”, “Hugo”, “Steve” and “Xavier”. When I set the valueMin to ‘A’ and valueMax to ‘Z’ I receive all names. When I set valueMax to ‘X’, “Xavier” is NOT returned. That is because “Xavier”.CompareTo(“X”) returns 1 and 1 is not <= 0. Writing my own string comparer is not possible in this scenario because it would not be used by the Entity Framework. So I have to find a workaround. And here is the LINQ statement that works fine for me:

       1: string valueMin = "A";

       2: string valueMax = "Z";

       3:  

       4: var x = from p in context.TPerson

       5:         where p.Name.ToLower().Substring(0, valueMin.Length).CompareTo(valueMin.ToLower()) >= 0 &&

       6:               p.Name.ToLower().Substring(0, valueMax.Length).CompareTo(valueMax.ToLower()) <= 0

       7:         select p;

Remembering the above problem I have to find a way where “Xavier”.CompareTo(“X”) results in –1 or 0 to make my query work. So –1 would be the wrong result, what I really want is that it return 0. CompareTo() will return 0 when both values are equal. So lets make them equal… Therefore all values are converted to lower (or upper) case. Than we shorten the queried value to the length of the filter value. In result we get the following statement: “x”.CompareTo(“x”) which results in 0. So the above query works as expected.

The query by valueMin = ‘A’ and valueMax = ‘A’ returns all persons where the name starts with ‘A’.

Dynamic where with Entity Framework

2009-03-18T17:18:54Z

In my last project I have to implement a dynamic where filter for some date stored in the Enitity Framework (EF) model. The next picture shows the DB schema of the data.

This is a common scenario to store multiple properties of a single item in a very dynamic way. The TItemProp table has a foreign key relation to the TItem table. The PropKey column in the TItemProp table holds the key of the Property (e.g. “Name”) and the PropValue column stores the value of that property (e.g. “Stephe”).

Now I have to filter some items from the TItem table with some specific properties using the EF in a simple one-to-one mapping (for more I will wait for v2 ;-).

Using LINQ to Entity a static way could be:

        1: using (EFTestEntities context = new EFTestEntities())

       2: {

       3:     var items = from item in context.TItem.Include("TItemProp")

       4:                 where item.TItemProp.Count(ip => ip.PropKey == "PropA" && ip.PropValue == "abc") > 0 &&

       5:                       item.TItemProp.Count(ip => ip.PropKey == "PropB" && ip.PropValue == "cde") > 0

       6:                 select item;

       7:  

       8:     return items.ToList();

       9: }

That is what I want to do. But I need it a bit more dynamic…

       1: using (EFTestEntities context = new EFTestEntities())

       2: {

       3:     var items = from item in context.TItem.Include("TItemProp")

       4:                 select item;

       5:  

       6:     items = items.Where(i => (i.TItemProp.Count(ip => ip.PropKey == "PropA" && ip.PropValue == "abc")) > 0);

       7:     items = items.Where(i => (i.TItemProp.Count(ip => ip.PropKey == "PropB" && ip.PropValue == "cde")) > 0);

       8:  

       9:     return items.ToList();

      10: }

That gives me what I want to do, but still the list of parameters is not dynamic. Therefore I will create a Dictionary which holds the Key Value collection and use a foreach loop to build the filter.

       1: Dictionary<string, string> props = new Dictionary<string, string>();

       2: props.Add("PropA", "abc");

       3: props.Add("PropB", "cde");

       4:  

       5: using (EFTestEntities context = new EFTestEntities())

       6: {

       7:     var items = from item in context.TItem.Include("TItemProp")

       8:                 select item;

       9:  

      10:     foreach (var prop in props)

      11:     {

      12:         items = items.Where(i => (i.TItemProp.Count(ip => ip.PropKey == prop.Key && ip.PropValue == prop.Value)) > 0);

      13:     }

      14:  

      15:     return items.ToList();

      16: }

I thought I was done right now, but when I run my project I recognized, that my result has changed for my last approach with the foreach loop. What went wrong here, it took me some time with the SQL-Profile to figure out happen here. The generated SQL statements of all three codes where identical but in the last one the parameters went wrong. Instead of passing P1 = “PropA”, P2 = “abc”, P3 = “Propb” and P4 = “cde” the last version passes P1 = “PropB”, P2 = “cde”, P3 = “Propb” and P4 = “cde”. That where two times the last parameter. If I change the order of the parameters in my Dictionary the other parameter was passed twice. To solve this proplem I have to introduce two more variables; key and value. Assigning the values first to the variables and using them in the LINQ statement results in the correct behavior. Here is the code that worked for me:

       1: Dictionary<string, string> props = new Dictionary<string, string>();

       2:  

       3: props.Add("PropA", "abc");

       4: props.Add("PropB", "cde");

       5:  

       6: using (EFTestEntities context = new EFTestEntities())

       7: {

       8:     var items = from item in context.TItem.Include("TItemProp")

       9:                 select item;

      10:  

      11:     foreach (var prop in props)

      12:     {

      13:         string key = prop.Key.ToString();

      14:         string value = prop.Value.ToString();

      15:  

      16:         items = items.Where(i => (i.TItemProp.Count(ip => ip.PropKey == key && ip.PropValue == value)) > 0);

      17:     }

      18:  

      19:     return items.ToList();

      20: }

There seems to be some strange behavior LINQ to EF is handling passed parameters. I think this is related to the deferred execution of LINQ statements and that the reference to the specific key value pair get lost.

So be careful by passing values to a LINQ statement!

Update for Silverlight 2

2009-02-19T15:07:44Z

Microsoft has just released a update for Silverlight 2. The release version was Silverlight 2 RTW (2.0.31005.0). This update installs version Silverlight 2 GDR 1 (2.0.40115.0) [GDR stands for General Distributed Release]. This is only a bug fix release and has no additional features in it. To get the latest version of Silverlight go to:

http://www.microsoft.com/silverlight/resources/install.aspx

There should be a updated version of the dev tools in near future so check out this site for the latest Silverlight Tools for Visual Studio 2008 SP1:

http://www.microsoft.com/downloads/details.aspx?FamilyId=c22d6a7b-546f-4407-8ef6-d60c8ee221ed&displaylang=en

Microsoft has released Service Pack 3 for SQL Server 2005

2008-12-16T10:00:37Z

On 15. December Microsoft has released Service Pack 3 for SQL Server 2005. The new version number after applying the service pack is 9.00.4035. You can find the download here:

http://www.microsoft.com/downloads/details.aspx?FamilyID=ae7387c3-348c-4faa-8ae5-949fdfbe59c4&displaylang=en

More information about the Service Pack 3 you can find here:

http://msdn.microsoft.com/en-us/library/dd353312(SQL.90).aspx

Silverlight Tools for Visual Studio 2008 SP1 final available

2008-10-28T15:49:00Z

Regarding to my last post here is the Link to the final of the Microsoft Silverlight Tools for Visual Studio 2008 SP1:
http://www.microsoft.com/downloads/details.aspx?FamilyId=c22d6a7b-546f-4407-8ef6-d60c8ee221ed&displaylang=en

Silverlight 2 is available for Download

2008-10-14T09:26:00Z

Download Silverlight 2 here:
http://www.microsoft.com/silverlight/

Microsoft Silverlight Tools for Visual Studio 2008 SP1 (RC1) can be found here:
http://www.microsoft.com/downloads/details.aspx?FamilyID=c22d6a7b-546f-4407-8ef6-d60c8ee221ed&DisplayLang=en

Microsoft Silverlight 2 SDK can be found here:
http://www.microsoft.com/downloads/details.aspx?FamilyID=8d933343-038f-499c-986c-c3c7e87a60b3&DisplayLang=en

Microsoft Expression Blend 2 SP1 (Blend 2.5 Preview is now named SP1) can be found here:
http://www.microsoft.com/downloads/details.aspx?FamilyId=EB9B5C48-BA2B-4C39-A1C3-135C60BBBE66&displaylang=en

The Silverlight 2 RTW (Release To Web) has the Version 2.0.31005.0. You can check the installed version by clicking on "Silverlight Configuration" on any Silverlight application.

Saving not permitted in SQL Server Management Studio 2008

2008-09-04T19:01:00Z

"Saving changes is not permitted. The changes you have made require the following tables to be dropped ..."

I found that this is one of the most annoying default settings I ever saw in a development tool.
In this dialog you can save the text to a text file (not very helpful here) or cancel the save action of the item you are working on.

To prevent SQL Server Management Studio 2008 to show that message while you are developing a database schema go to the Options.
Tools -> Options -> Designers -> Table and Database Designer and uncheck the "Prevent saving changes that require table re-creation".