November 4, 2010

Reactive Extensions

For the past couple of weeks I’ve been looking into the Reactive Extensions framework. This resulted into a presentation for some of my colleagues about what Rx is, how it can be used and some of the cool stuff you can do with it. I delivered that presentation yesterday evening. Today I wanted to share the sources of the demo’s I’ve used during this presentation. You can download these from here: RxDemos.

January 25, 2010

Throttling workflow services

For the project I’m currently working on I did some research into the throttling of workflow services using WCF and WF with .NET 3.5. We didn’t have much experience with throttling of services, let alone workflow services so we decided to some simple tests to determine the possibilities and effects of throttling. Before diving into the technical details of how to do throttling I want to look at the scenario we had.

November 18, 2009

Creating a workflow image from a workflow service

Introduction For the project I’m currently working on we wanted to be able to display an image of a running workflow instance for diagnostic purposes. There are numerous examples of this floating around the internet, but most of them focused on a client side application that would generate the image. This is fine if your client application has access to all the necessary assemblies, but if does not you’re going to run into some problems.

March 2, 2009

Even better message based correlation

As a follow up to my previous post, I’ve been extending my implementation a bit. In the comments section of my last post you might have read that we were thinking about creating a CorrelationSequenceActivity. I’ve implemented this activity now and it currently accepts only one child activity which should be a ReceiveActivity. This is validated using an activity validator. It has an attached property called CorrelationKey which will then appear on the ReceiveActivity.

February 24, 2009

Message based correlation with WF/WCF in .NET 3.5

When .NET 3.0 was released we got Windows Communication Foundation (WCF) and Windows Workflow Foundation (WF). These were great technologies, but they would have been even greater if they were used together. Unfortunately, Microsoft decided not to include this for .NET 3.0. However, with the release of .NET 3.5 we got the WCF Send and Receive activities that you can use in your workflows in order to implement a WCF service contract by using a workflow.

June 19, 2008

Workflows mysteriously being aborted

Part of the project I’m currently working on involves a workflow system we have build ourselves on top of Windows Workflow Foundation. It consist of a WCF service that contains task, a front end that displays these to users and of course several workflow activities for creating tasks and waiting for them to be completed by the users. Last Friday it was finally time to perform an installation of the system on our acceptance environment so the users could test it.

June 10, 2008

Service Pack 1 for .NET fixes XML serialization?

Today we ran into an issue with a Windows Forms application we had written. It was working fine on our development virtual PC’s, but for some reason it failed on the actual host machines that we needed it to run on. The application is written purely against the .NET Framework version 2.0. We do communicate with a service that is using WCF, which is part of the .NET Framework version 3.

May 23, 2008

Cool tools: NetMassDownloader

Today I was working on an issue in our application that was brought to our attention by one of the users. So I started investigating this issue and soon found out that the problem was situated in our ASP.Net front end. While I was debugging and analyzing the call stack I found out that something went wrong between the page that is being posted and the Mediator, which is responsible for actually saving the data to our back end services.

April 30, 2008

Issue fixed

I thought I’d write a little follow up on my previous post. We found out yesterday that the bug we found in Windows Workflow Foundation which caused us to make a work around, has been fixed in the recently released .NET Framework 2.0 and 3.0 SP1. We haven’t been able to find a mention of this bug in the release notes, but we had a small application that showed the bug was there, so we tested it on our development machine which were using the service packs and then on a test server which didn’t have the service pack installed and it showed that it was working find on our development machines, but it didn’t work on our test servers.

April 28, 2008

State machine workflows

At the beginning of last week a report came in from our users which said that they were experiencing timeout issues while working with the application that has been running in production quite stable since the beginning of this year. Because this was a blocking issue we quickly started investigating what went wrong. After looking at the code for about half an hour we decided we needed to put on tracing to find out what really happens.

September 19, 2007

WF: Required bindable properties

Today I was working on a bit of workflow we have in our project. We’ve written a couple of activities to handle some of the processing done in our application (such as sending out emails at a specified point in time). These activities have been working quite well, but they lacked some kind of validation on required properties or how they were used in the workflow. So I was assigned the task to implement some of that stuff.

September 6, 2007

Silverlight 1.0 RTM

As my colleague Willem mentioned, Microsoft has finally released Silverlight 1.0. I find it amazing how fast this technology has gone. A year ago nobody heard of Silverlight, and now there is a first release. Although I’m quite impressed by the features of Silverlight 1.0, I think that Silverlight 1.1 has far more potential. Having the power of C# inside the browser, that must be awesome. It is going to open up a lot of possibilities for a richer end-user experience, while a lot of the advantages of web applications are still there.