Last week I had the pleasure of attending the 4DotNet event in Zwolle, The Netherlands. Next to catching up with old friends, I enjoyed presenting and listening to two other talks

Pat Hermens | Learning from Failure – Finding the ‘second story’

The first speaker up was Pat Hermens. Pat talked to us about Failure. Going over three examples exploring how a catastrophic event came to be, continuously returning to the question: was this a failure [by someone]? His point was that the answer was “no” in all these cases. Instead of focusing on what we believe was a mistake or human error in hindsight, we should focus on the circumstances that made a such an error even possible. Assuming no ill intent, no one wants a nuclear meltdown or a space shuttle crash to occur – still they did while everyone believed they were making correct decisions. Focusing on the second story, or the circumstances or culture that allowed the wrong decision to look like a good decision is the way forward in his opinion.

Patrick Schmidt | Valkuilen bij het maken van high performance applicaties

Next up was Patrick Schmidt. Patrick talked about some .NET internals and explained how you can still create memory leaks in a managed language. He showed how creating a labda function that uses a closure over large object can end in memory leaks. He then moved on to explain some garbage collector internals and how incorrect usage of object creation and destruction can ruin your performance. Of course the prime example of string concatenation vs. the StringBuilder came along here. Finally, he talked about some pitfalls when using Entity Framework: the 1+ n problem and how you can accidentally download a whole table and only do the selection in memory by mixing up IQueryable and IEnumerable.

Henry Been | Logging, instrumentation, dashboards, alerts and all that – for developers

For the final session I had the privilege of presenting myself. In this session I share what I have learned about monitoring and logging over the last year when using Azure Monitor in a number of applications. The slidedeck for this session can be downloaded. If you are looking for an example application to try things out yourself, you can continue working with the example I showed during the talk.


If you have read any of my blogs before, or know me only a little bit, you know I am a huge fan of ARM templates for Azure Resource Manager. However, every now and then I run into some piece of infrastructure that I would like to set up for my application only to find out that it is not supported by ARM templates. Examples are Cosmos DB databases and collections. Having to createIfNotExists() these was always a pain to code and also mixes the responsibility of resource allocation up with business logic. But no more as part of all the #MSBuild news, the following came in!

As of right now, you can specify the creation of an CosmosDB database and collection, using ARM templates. To create a CosmosDB database for use with the SQL API, you can now use the following template:

After setting up a database, it is time to add a few containers. In this case I already provisioned throughput at the database level, so I can add as many containers as I need without additional cost. But, let’s start with just one:

I cannot just create the container and specify the, now mandatory, PartitionKey but also specify custom indexing policies. Putting this together with the template that I already had for creating a CosmosDB account, I can now automatically create all the dependencies for my application using the following ARM template:

I hope you enjoy CosmosDB database and collection support just as much as I do, happy coding!