How to find the end user's IP address in a cloud environment

We noticed today that one of our ASP.NET cloud applications incorrectly identified the end user's IP address. Our Request.ServerVariables["REMOTE_HOST"] and Request.ServerVariables["REMOTE_ADDR"] were initialized with the load balancer information instead of the end user's data.

We found the end user's IP in a different place: Request.Headers["X-Cluster-client-IP"].

Happy coding!

Modelus.Com Terms of Use updated

Modelus.Com site's Terms of Use have been updated. If you post comments on our blog, make sure you read, understand, and agree with our blog comment policy and blog comment guidelines outlined in the Terms of Use.

You can find links to Modelus.Com Terms of Use and Privacy Policy in the footer at the bottom of the page.

Silverlight 3 released

The long waited Silverlight 3 and its development tools have been released by Microsoft.

Farewell, Silverlight 2. Welcome, Silverlight 3!

Stuart Halloway speaks on Clojure at OTUG on Tue, July 21, 2009

Stuart Halloway, co-founder of Relevance, Inc, will be speaking on Clojure at OTUG on Tuesday, July 21, 2009.

Who: Stuart Halloway
What: Clojure, a dynamic language that compiles directly into JVM bytecode.
When: Tuesday, July 21, 2009
5:30 - 6:30 pm - Social Hour and Pizza Dinner
6:45 - 9:30 pm - Introduction and Presentation
Where: O'Shaughnessy Science LL 18, University of St. Thomas, St. Paul, MN
Cost: $25. Free to UST students and faculty.

RSVP is required. See more information at

How to set up FDF Toolkit on Windows Server 2008 and IIS 7

I have been moving a number of web applications from 64-bit Windows Server 2003 and IIS 6 running in 32-bit mode to 64-bit Windows Server 2008 and IIS 7. During testing we discovered the following COM exception when trying to pre-populate an FDF form using FDF toolkit 6:

0x80040154: Retrieving the COM class factory failed.

It turned out that FDF Toolkit 6 has been compiled only for a 32-bit OS. Thus, in order to make it work with IIS 7, you will need to register FDF Toolkit using the 32-bit version of regsvr32.exe. You will also need to enable 32-bit applications in your application pool.

Happy coding!

IE 8 and Dojo 1.1 issues resolved by upgrading to Dojo 1.3

According to our web statistics, IE8 user base is growing fast at the expense of IE6 and IE7 users. This prompted us to test our web applications using IE8 and, as a result, we discovered a number of CSS and JavaScript compatibility issues.

Most of the JavaScript problems were related to the Dojo 1.1 JavaScript toolkit and all of them have been resolved by upgrading to Dojo 1.3.

If you are wondering which browsers your applications should support, we recommend establishing a rule based on a percentage of your user base. For example, we support 95% of our users, which results in IE 6/7/8, Firefox 3, Chrome 2, and Safari 3 browsers.

Happy coding!

Modelus A3 Report Templates made available for download

I am pleased to announce that we made our standard templates for A3 reports available as a free download from website:

Earlier this year, I have reviewed Managing to Learn by John Shook and Understanding A3 Thinking by Durward K. Sobek II and Art Smalley. Both of these books have been highly influential on the design of the templates. Check them out.


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