Search results for 'app:weblogs' matching tag 'NetFx3'

Workflow 4 and Visual Basic expressions

Maurice — Mon, 26 Oct 2009 05:00:00 GMT

When using Windows Workflow Foundation 4 you often need to enter expression in some activity property. The new thing is these expressions are all in the Visual Basic dialect regardless of what language you project is in. So when developing a project in C# the expressions are sill in Visual Basic.

Weird right?

Well not really when you think about it!

After all power business users are expected to be able to modify workflows. And guess what their favorite tools are. That would be Microsoft Excel and Word. And what do they use to create macros? Right Visual Basic for Applications is their language of choice.

So if they use VBA letting them enter VB into expression dialogs is a far more natural fit than having them use C#.

A case for the Delay activity

So lets take a look at the delay activity. This activity takes 1 input property Duration of type Time Span. So I guess that means our VBA power users are going to have to enter something like if they want to wait 5 seconds:

Now for some reason I suspect that is not the first thing they are going to type. In fact they are more likely to time something like “0:0:05” instead. Not very VB like right?

Well it turns out workflow is smart enough to realize it can convert the string literal to a Time Span and use this. So when our power users does the following it just works

Nice, I like this!

Enjoy WF4!

www.TheProblemSolver.nl
Wiki.WindowsWorkflowFoundation.eu

Nederlandse CodeCamp 2009

Maurice — Mon, 19 Oct 2009 05:00:00 GMT

Op 21 november 2009 organiseren de SDN, Stichting dotNed en VBcentral samen het derde Nederlandse Code Camp. Dit is een dag lang met code, code sharing, freaking en gezellig samenzijn. Een evenement door ontwikkelaars, voor ontwikkelaars. De regie ligt voor een belangrijk deel bij de deelnemers! Het aantal plaatsen voor deelnemers is wel beperkt tot maximaal 150. Wacht dus niet te lang met beslissen want voor je het weet is er geen plaats meer. Vergeet bij je aanmelding niet op te geven welke onderwerpen je interesse hebben. Bovendien nodigen we iedereen graag uit om zelf een sessie in te vullen.

Op de website, www.codecamp.nl, vind je meer informatie en kan je je aanmelden.

Sending your own objects to a WF4 workflow

Maurice — Thu, 20 Aug 2009 05:00:00 GMT

In the previous two blog posts (here and here) I showed how to create and expose a Windows Workflow Foundation 4 workflow via WCF and have both a workflow and a regular C# client work with it. But the parameter and return value where real simple with just a string each. So how about passing some more complex data.

To show how to do so I will replace the singe string with a person object. Admittedly not the most complex person with only an id, first and last name and their birth date but enough to demonstrate the principal.

The main of the service, which uses a WorkflowServiceHost, stays exactly the same so see the first blog post for that part. The CreateWorkflow() function will change now reflecting the fact that the service will no longer expect a string but a person object.

private static WorkflowElement CreateWorkflow()

    var result = new Sequence();

    var input = new Variable<Person>();

    result.Variables.Add(input);

    XNamespace ns = "http://tempuri.org";

    var handle = new Variable<CorrelationHandle>();

    result.Variables.Add(handle);

    var receive = new Receive()

        OperationName = "Operation1",

        ServiceContractName = ns + "MyService",

        Value = new OutArgument<Person>(input),

        AdditionalCorrelations = {

           {"ChannelBasedCorrelation", new InArgument<CorrelationHandle>(handle)}

},

        CanCreateInstance = true

};

    result.Activities.Add(receive);

    var write = new WriteLine()

        Text = new InArgument<string>(env => string.Format("\tThe workflow was called with '{0}'.", input.Get(env)))

};

    result.Activities.Add(write);

    var reply = new SendReply()

        Request = receive,

        Value = new InArgument<string>("The result")

};

    result.Activities.Add(reply);

    return result;

Not a big change really as we only have to change the input variable from Variable<string> to Variable<Person> and do the same with the Value property of the Receive activity which goes from new OutArgument<string>(input) to new OutArgument<Person>(input).

That leaves the Person class and this is just straightforward WCF work by turning the basic class into a data contract.

[DataContract(Namespace = "urn:WF4Sample:person")]

public class Person

    [DataMember]

    public int Id { get; set; }

    [DataMember]

    public string FirstName { get; set; }

    [DataMember]

    public string LastName { get; set; }

    [DataMember]

    public DateTime BirthDate { get; set; }

    public override string ToString()

        return string.Format("{0} {1} was born on {2} (ID: {3})", FirstName, LastName, BirthDate, Id);

Again no big deal

So with the service done we need to make the same changes to the two client applications. First the workflow client using the Send activity.

The Person class is exactly the same as on the server so just copy the code as is. Again the main in the workflow client doesn’t change, see the first blog post for that part. The part that does change a little is the CreateWorkflow() function so it creates and sends a Person instead of a string. The code goes as follows:

private static WorkflowElement CreateWorkflow()

    var result = new Sequence();

    XNamespace ns = "http://tempuri.org";

    var endpoint = new Endpoint()

        Uri = new Uri("http://localhost:8090/Sequence1/Operation1"),

        Binding = new BasicHttpBinding()

};

    var response = new Variable<string>();

    result.Variables.Add(response);

    var handle = new Variable<CorrelationHandle>();

    result.Variables.Add(handle);

    var person = new Person()

        Id = 7,

        FirstName = "Maurice",

        LastName = "de Beijer",

        BirthDate = new DateTime(1962, 8, 24)

};

    var request = new Send()

        OperationName = "Operation1",

        Endpoint = endpoint,

        AdditionalCorrelations =

           {"ChannelBasedCorrelation", new InArgument<CorrelationHandle>(handle)}

},

        ServiceContractName = ns + "MyService",

        Value = new InArgument<Person>(person)

};

    result.Activities.Add(request);

    var reply = new ReceiveReply()

        Request = request,

        Value = new OutArgument<string>(response)

};

    result.Activities.Add(reply);

    var write = new WriteLine()

        Text = new InArgument<string>(response)

};

    result.Activities.Add(write);

    return result;

Again a very minor change.

So how about the C# console client from the second blog post?

The service contract changes a little and is now:

[ServiceContract]

interface MyService

    [OperationContract]

    Operation1Response Operation1(Person request);

The person class is very different from the service though and looks like this:

[MessageContract(WrapperNamespace = "urn:WF4Sample:person")]

internal class Person

    [MessageBodyMember(Namespace = "urn:WF4Sample:person")]

    public int Id { get; set; }

    [MessageBodyMember(Namespace = "urn:WF4Sample:person")]

    public string FirstName { get; set; }

    [MessageBodyMember(Namespace = "urn:WF4Sample:person")]

    public string LastName { get; set; }

    [MessageBodyMember(Namespace = "urn:WF4Sample:person")]

    public DateTime BirthDate { get; set; }

But besides the difference from using a message contract as opposed to a data contract this isn’t a big deal.

The main program changes a bit but not a whole lot. Again the only changes are due to the fact we are passing in a Person instead of a string.

static void Main(string[] args)

    var binding = new BasicHttpBinding();

    var endpoint = new EndpointAddress("http://localhost:8090/Sequence1/Operation1");

    var factory = new ChannelFactory<MyService>(binding, endpoint);

    var proxy = factory.CreateChannel();

    var request = new Person()

        Id = 23,

        FirstName = "Joe",

        LastName = "Regular",

        BirthDate = new DateTime(1975, 7, 1)

};

    var result = proxy.Operation1(request);

    Console.WriteLine(result.Value);

    Console.WriteLine("Regular client is done.");

    Console.ReadLine();

All together not bad.

But so far we have only used a very simple workflow with a single message send to it. Suppose you want to send multiple messages to the same workflow? Well in that case we need to use message correlation as we will see next time.

Enjoy!

www.TheProblemSolver.nl
Wiki.WindowsWorkflowFoundation.eu

Using Windows Workflow Foundation 4 Receive from an non WF client

Maurice — Wed, 19 Aug 2009 05:00:00 GMT

In a previous blog post I described how to use the WorkflowServiceHost and host a workflow with a Receive activity that waits for WCF messages. I also added a WF4 client that called the service and received a response. However a lot of clients out there are not going to be workflows but “regular” code that calls into out workflow. So what does it take to have a simple console application talk to our WF4 service?

The first thing we need is an service contract describing the operation we can call. In our workflow the operation is named “Operation1” and our service contact name was “MyService” with the default namespace of “http://tempuri.org”. So our service contract looks like this:

[ServiceContract]

interface MyService

    [OperationContract]

    Operation1Response Operation1(Operation1Request request);

Next up are the request and response objects. In this case I am using just two strings so they are pretty simple as well.

[MessageContract(IsWrapped = false)]

public class Operation1Request

    [MessageBodyMember(

        Namespace = "http://schemas.microsoft.com/2003/10/Serialization/",

        Name = "string")]

    public string Value { get; set; }

[MessageContract(IsWrapped = false)]

public class Operation1Response

    [MessageBodyMember(

        Namespace = "http://schemas.microsoft.com/2003/10/Serialization/",

        Name = "string")]

    public string Value { get; set; }

The interesting to note here is that I have to use a MessageContact instead of a DataContract and I have to make sure the data isn’t wrapped in an extra element. Also interesting is the fact that the data is send across using the name “string”, not the easiest C# identifier to work with so I called them “Value” instead.

Using these WCF definitions creating a simple console app that calls the workflow is a breeze.

static void Main(string[] args)

    var binding = new BasicHttpBinding();

    var endpoint = new EndpointAddress("http://localhost:8090/Sequence1/Operation1");

    var factory = new ChannelFactory<MyService>(binding, endpoint);

    var proxy = factory.CreateChannel();

    var request = new Operation1Request()

        Value = "Test from a console."

};

    var result = proxy.Operation1(request);

    Console.WriteLine(result.Value);

    Console.WriteLine("Regular client is done.");

    Console.ReadLine();

Enjoy!

www.TheProblemSolver.nl
Wiki.WindowsWorkflowFoundation.eu

What does Windows Workflow Foundation 4 mean for existing workflow developers?

Maurice — Fri, 03 Jul 2009 05:00:00 GMT

The question of what Windows Workflow Foundation version 4 means for developers currently developing using WF recently came up. As I mentioned before WF 4 is a complete rewrite and doesn’t use any of the existing WF 3 classes. The design of WF 4 is even quite different from the design of WF 3.

So are WF 3 developers completely left in the dark and have to start from scratch? And what about their existing applications, will they still run on .NET 4 or are they stuck in .NET 3.5 until the end of times?

Fist of all let me address why I believe Microsoft could make such a radical change. Keep i mind this is just my personal opinion and I might be completely wrong .

WF 3 was never widely adopted so I believe the team felt they could do this and not create to much of a problem. Personally I don't think the low adoption of WF 3 had anything to do with the technology. Sure it has its problems but most people never got to the point that they ran into real technical issues. Instead most people looked, didn't understand and quit. So IMHO the main problem was far more a question if evangelism that technology.

So what is the big issue with a migration from WF 3 to WF 4?

One big issue with WF 4 is that Microsoft decided not to release a state machine implementation. In WF 3 there was a choice between state machine and sequential workflows. In WF 4 there is a choice between sequential and flow chart. And in WF 3 a state machine turned out to be far more flexible and useful and quite a few cases are not really covered by the WF 4 model. There are a few workarounds to do something like a state machine in WF 4 but they are not pretty. That said, a number of state machine workflows could very well be done using a flow chart.

As far as backward compatibility the story is a bit more complicated. WF 4 ships with an interop activity you can use to host custom WF 3 activities in a WF 4 workflow. How good or bad this is? I really don't know yet but given how different the two are I fear it is very limited.

But WF 3 developers need not worry about their existing projects!

There is however a second side to the compatibility story. .NET 4 will ship both with the WF 3 and the WF 4 runtimes. The WF 3 runtime will not be prominent but it will still be there so all existing WF 3 applications will continue to run as is. And because it is part of the current .NET framework I suspect this is a legal requirement (but then I am no lawyer so could be wrong here). So there is no reason for your clients to panic just yet .

So existing workflow developers should start learning WF 4 for future projects but can continue to keep using their existing WF 3 solutions for the foreseeable future.

Enjoy!

www.TheProblemSolver.nl
Wiki.WindowsWorkflowFoundation.eu

What does Windows Workflow Foundation 4 mean for existing workflow developers?

Maurice — Fri, 03 Jul 2009 05:00:00 GMT

Fist of all let me address why I believe Microsoft could make such a radical change. Keep i mind this is just my personal opinion and I might be completely wrong .

WF 3 was never widely adopted so I believe the team felt they could do this and not create too much of a problem. Personally I don't think the low adoption of WF 3 had anything to do with the technology. Sure it has its problems but most people never got to the point that they ran into real technical issues. Instead most people looked, didn't understand and quit. So IMHO the main problem was far more a question if evangelism that technology.

So what is the big issue with a migration from WF 3 to WF 4?

But WF 3 developers need not worry about their existing projects!

So existing workflow developers should start learning WF 4 for future projects but can continue to keep using their existing WF 3 solutions for the foreseeable future.

Enjoy!

www.TheProblemSolver.nl
Wiki.WindowsWorkflowFoundation.eu

Want to download all MIX sessions?

Maurice — Tue, 31 Mar 2009 05:00:00 GMT

Then you should check Mike Swanson’s blog post here. He has two batch files, the first downloads all MIX session recordings with in the format you like, the second renames them so it is easier to make sense of all the media file names.

If you just want a list of all sessions with download links this page might be the thing for you.

So much better than downloading them by hand. Not as good as going to the MIX itself but if you, like me, couldn’t go it is still a nice way to see all the content.

Enjoy!

Software Development Event march 30th

Maurice — Mon, 23 Mar 2009 05:00:00 GMT

Just one week to go to the next Software Development Event. The schedule with all the sessions is looking good. But this time there is even more!

We will have a Microsoft Surface machine somewhere in the common area for people to try our. And if you have never played, oops tested, with a Surface machine before this is a truly exiting machine!

Just goes to show, the SDN will go to extraordinary efforts to please all attendees

You can see the full schedule here. And don’t forget, we are not in Ede this time but in a great new location in Driebergen.

Hope to see everyone there next week Monday.

www.TheProblemSolver.nl
Wiki.WindowsWorkflowFoundation.eu

And now on Twitter at http://twitter.com/mauricedb.

Using Windows Workflow Foundation with Windows Communication Foundation

Maurice — Sat, 21 Mar 2009 05:00:00 GMT

Attached are the PowerPoint presentation and samples from my WF with WCF presentation in Timisoara, Romania. Thanks to Ineta for providing the funding for this.

Download the PowerPoint and samples

Unleash the power of State Machine Worklfows

Maurice — Sat, 21 Mar 2009 05:00:00 GMT

Attached are the PowerPoint presentation and samples from my state machine workflow presentation in Timisoara, Romania. Thanks to Ineta for providing the funding for this.

Download the PowerPoint and samples