Understanding Extenders in the Itinerary Designer

By Nick Hauenstein

I was lurking around the ESB Toolkit forums yesterday, and got involved in an exchange with someone who was hitting the same roadblock to the Itinerary Designer that a lot of people hit: confusion with the model elements and extenders. Upon my first exposure to the Itinerary Designer it took me a week to get over the learning curve of this, and to understand why every send operation seemingly involved two off-ramp shapes instead of one.

Now in the case of that thread, the problem was actually not having a properly formatted SOAP request for the service that was going to be invoked (also a fairly common issue), but getting to the actual issue took cutting through some of the confusing bits of how the itinerary services themselves are implemented, and what they do.

That being said, I took some time last night to write up an article on the different model elements in the itinerary designer, their extenders, and how they can be used to compose an itinerary. You can access the article here: Making Sense of Model Elements and Extenders in the Itinerary Designer

Side note: The article is now part of the brand new (and still under-construction) QuickLearn Technical Library, which will soon contain many more similar articles and links to technical resources for all of the technologies about which QuickLearn teaches.

That’s all for now!

Implementing Simple Discovery using WCF

By Nick Hauenstein

Imagine that you have written an application that will need to invoke a service at some point. You can hard code the service address, you could place it in configuration, you can stick it into an external registry (a la UDDI), or you could come up with some custom method for resolution (e.g., storing endpoint information in a table of a SQL database).

However, Juval Lowy reminds us that we don’t have to re-invent the wheel. He wrote an excellent article in last month’s MSDN magazine about simple discovery in WCF. In the article he provides a simple explanation of what it is, and how it works, and even provides sample classes that can jump-start your development.

You can check out the article here: Foundations – Discover a New WCF with Discovery