code
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Fast projections
Most EventStore client libraries allow you to subscribe to a stream by passing in a callback which is invoked when an e... -
Commands and events with JustSaying and AWS
I've been looking into handing a bit of our messaging infrastructure over to a managed alternative. Managing your own me... -
Using a batch layer for fast(er) aggregations
In the oldest system I'm maintaining right now, we have an account aggregate that, next to mutating various balances, pr... -
Notifications from an event log
User notifications are a feature that came as an afterthought, but turned out to be rather easy to implement - without t... -
Functional one-liner for running totals in C#
Visualizing some data earlier this week I had to compute the [running total](https://en.wikipedia.org/wiki/Running_total... -
Visualizing event streams
In my recent talk on [Evil by Design](http://www.jefclaes.be/2015/11/slides-from-my-talk-evil-by-design-at.html), I show... -
Bulk SQL projections with F# and type providers
Early Summer, I had to set up an integration with an external partner. They required of us to daily provide them with a ... -
Aspect ratio calculation
Earlier today I was writing a migration script in F\# where I had to calculate the aspect ratio based on the given scree... -
Basic casino math
In a previous series of posts, I went over the models used by casinos to spin a wheel ([spinning](http://www.jefclaes.be... -
Consumed: Queries and projections (F#)
This is the third post in my series on porting a node.js application to an F\# application. So far, I've looked at ... -
Consumed: Handling commands (F#)
As [I wrote earlier](http://www.jefclaes.be/2015/04/parsing-command-line-arguments-with-f.html), I've been working on po... -
Finding unused code (F#)
Coming from C\#, I'm used to the compiler warning me about unused variables. Relying on the compiler to help me with [ch... -
Consumed: Parsing command line arguments (F#)
Last year, I set out to write my first node.js application; a small web application for keeping lists of [everything I c... -
Checked errors in F#
In the land of C\#, exceptions are king. [By definition](https://msdn.microsoft.com/en-us/library/ms173160(v=vs.80).aspx... -
Scaling promotion codes
In our system a backoffice user can issue a promotion code for users to redeem. Redeeming a promotion code, a user recei... -
Domain Language: The Playthrough Bonus
Since online gambling has been regulated in Belgium, basically each eligible license holder has complemented their land ... -
Averages are not good enough (F#)
Let's (no pun intended) look at a set of response times of a web service. ```fsharp let responseTimes = [ 18.0; 21.0;... -
Spinning the wheel: clustering and near misses
The previous post showed a simple model casinos use to manipulate the odds. Instead of relying on the physical wheel for... -
Spinning the wheel: manipulating the odds
The previous post defined a basic set of data structures and functions to spin a wheel of fortune in F\#. There was... -
Spinning the wheel
In this post, I'll define a basic set of data structures and functions to spin a wheel of fortune. In the next post, I'l... -
Hot aggregate detection using F#
Last week, I wrote about [splitting a hot aggregate](http://www.jefclaes.be/2014/11/splitting-hot-aggregates.html). Disc... -
Programmatically force create a new LocalDB database
I have spent the last week working in an integration test suite that seemed to be taking ages to run its first test. I r... -
Print out the maximum depth of recursion allowed
[Karl Seguin](https://twitter.com/karlseguin) tweeted the following earlier this week: "An interview question I sometime... -
Read an Event Store stream as a sequence of slices using F#
I'm slowly working on some ideas I've been playing around with whole Summer. Since that's taking me to unknown territory... -
Glueing the browser and POS devices together
I have been occupied building a modest Point of Sale system over these last few weeks. Looking at implementing the clien... -
Rebinding a knockout view model
As you might have noticed reading my last two posts, I have been doing a bit of front-end work using [knockout.js](http:... -
Sending commands from a knockout.js view model
While I got to use [angular.js](http://angularjs.org/) for a good while last year, I found myself returning to [knockout... -
Building a live dashboard with some knockout
Last week, we added a dashboard to our back office application that shows some actionable data about what's going on in ... -
Alternatives to Udi's domain events
Almost four years ago [Udi Dahan introduced an elegant technique](http://www.udidahan.com/2009/06/14/domain-events-salva... -
Reading an EventStore stream using JavaScript
Over Christmas break, I set out three days to play with the [EventStore](http://geteventstore.com/). One of the things I... -
Command and event semantics
Yesterday, I read [this blog post by Michael Feathers](https://michaelfeathers.silvrback.com/when-it-s-okay-for-a-method... -
An event store with optimistic concurrency
Like I mentioned [last week](http://www.jefclaes.be/2013/11/event-source-all-things.html) - after only five posts on the... -
Event projections
In my first two posts on event sourcing, I implemented [an event sourced aggregate from scratch](http://www.jefclaes.be/... -
An event store
Last week, I implemented [an event sourced aggregate from scratch](http://www.jefclaes.be/2013/10/an-event-sourced-aggre... -
An event sourced aggregate
Last week I shared [my theoretical understanding of event sourcing](http://www.jefclaes.be/2013/10/my-understanding-of-e... -
Eventual consistent domain events with RavenDB and IronMQ
Working on side projects, I often find myself using [RavenDB](http://ravendb.net/) for storage and [IronMQ](http://www.i... -
Angular.js and IE8 caching
Older Internet Explorer versions are notorious for agressively caching AJAX requests. In this post, you'll find two tech... -
Validating composite models with knockout validation
When you use [knockout validation](https://github.com/Knockout-Contrib/Knockout-Validation) to extend observables with v... -
Designing entities: immutability first
The first year I wrote software for a living I spent my days mostly writing forms over data applications; most of my eff... -
Reading large files in chunks with proper encapsulation
I've been doing some work lately which involves sequentially reading large files (> 2 to 5GB). This entails that it's... -
Putting my IronMQ experiment under stress
Two weeks ago, [I shared my first impressions of IronMQ](http://www.jefclaes.be/2013/03/first-ironmq-impressions.html). ... -
Some experimental infrastructure for IronMQ pull
I wrote about using [IronMQ as a cloud-based message queue](http://www.jefclaes.be/2013/03/first-ironmq-impressions.html... -
First IronMQ impressions
First time I touched messaging was in the first few years of my professional life working on software that supported fir... -
Raising events in commandhandlers
I've explored quite a few options on how to handle commands and queries in the last few posts. I finally settled on [thi... -
Organizing commands and queries
In the last few posts I settled on an architecture for handling commands and queries. A byproduct of [the described appr... -
RavenDB: Drop all collections
I never stub or mock the database when I'm using [RavenDB](http://ravendb.net/). Generally, I use an embeddable document... -
Separating command data from logic and sending it on a bus
In [my first post on this topic](http://www.jefclaes.be/2012/10/commands-queries-and-testing.html), I started out with a... -
Self-contained commands with dependencies
*Also read: [separating command data from logic and sending it on a bus](http://www.jefclaes.be/2013/01/separating-comma... -
Some notes on performance tuning with NHibernate
A few weeks back, I spent an intensive day performance tuning parts of a, to me, relatively unfamiliar part of our codeb... -
Commands with dependencies
*Also read: [Separating command data from logic and sending it on a bus](http://www.jefclaes.be/2013/01/separating-comma... -
Commands, queries and testing
*Also read:* 1. [*Self-contained commands with dependencies*](http://www.jefclaes.be/2013/01/self-contained-commands-w... -
Supporting the OPTIONS verb in ASP.NET Web API
[ASP.NET Web API](http://www.asp.net/web-api) controllers support only four HTTP verbs by convention: GET, PUT, POST and... -
Should I unit- or integration test my ASP.NET Web API services?
Over the last two weeks, preparing for a talk, I have been doing some research on [ASP.NET Web API](http://www.asp.net/w... -
HtmlHelper to generate a top-level menu for areas
Last week, we had to set up a new ASP.NET MVC web application, using a somewhat customized [Twitter Bootstrap](http://tw... -
Persisting model state when using PRG
I've been working on an ASP.NET MVC application in which we frequently apply the [Post/Redirect/Get pattern](http://en.w... -
Making my first NancyFx test pass
Like I already said last week, I have been dabbling a bit with [NancyFx](http://nancyfx.org/) lately. This week I t... -
Painless database logging with mongoDB
While browsing the source code of the [ELMAH mongoDB provider](https://github.com/CaptainCodeman/elmah-mongodb), I learn... -
Some Servicelocator pattern stinks
I have been working on a somewhat legacy codebase which makes use of the [Servicelocator pattern](http://martinfowler.co... -
Visualizing the offline application cache update progress
I wrote about using the HTML5 application cache [earlier](http://jclaes.blogspot.com/2012/03/html5-offline-web-applicati... -
Check for local file browsing with JavaScript
Because I do most of my research while commuting by train, I often pull entire websites offline using [httrack](http://w... -
Add images to a GitHub readme
Today I wanted to add some screenshots to a GitHub readme for the sake of documenting. While this wasn't particularly ha... -
How a web application can download and store over 2GB without you even knowing it
I have been experimenting with the [HTML5 offline application cache](http://www.w3.org/TR/html5/offline.html) some more ... -
HTML5 Offline Web applications as an afterthought in ASP.NET MVC
Recently I prototyped a mobile web application using ASP.NET MVC, [jQuery Mobile](http://jquerymobile.com/) and some HTM... -
ASP.NET MVC4 bundling in ASP.NET MVC3
One of the new wildly evangelized features of [ASP.NET MVC4](http://www.asp.net/mvc/mvc4) is the [built-in support for b... -
Testing DI bootstrappers
While your [Dependency Injection](http://martinfowler.com/articles/injection.html) bootstrappers - being responsible for... -
How Wikipedia uses HTML5 to save bandwidth
Something I hadn't noticed until recently is that Wikipedia tries to use the browser's native [SVG](http://www.w3.org/TR... -
Autocorrecting unknown actions using the Levenshtein distance
This weekend I prototyped an idea I had earlier this week: autocorrecting unknown actions in ASP.NET MVC. ### Handl... -
Rewriting an if
Yesterday I came across an if statement that looked something like this. ```csharp if (arg == "a" || arg == "b"... -
Programming for the future of mobile
I have been working on something small on the side lately. I hardly have anything to show for it though, most of it is s... -
Merge sorting in JavaScript
The latest addition to my [data structures and algorithms in JavaScript](https://github.com/JefClaes Data-structures-and... -
My js data structures and algorithms now on GitHub
If you have been reading my blog lately, you know that I'm implementing some data structures and algorithms in JavaScrip... -
Overoptimizing my JavaScript stack implementation for fun
[Davy Brion](http://davybrion.com/blog/) made a comment on [my JavaScript stack/queue implementation](https://jefclaes.b... -
Stacks and queues in JavaScript
The second assignment in my 'implementing data structures and algorithms in JavaScript' quest consists of two popular da... -
Simple sorting in JavaScript
About three years ago I graduated and got my degree in Applied Computer Science. Although it says Computer Science, we h... -
Checking for anonymous types
Because I blogged about anonymous types [last month](https://jefclaes.be/2011/04/anonymous-type-equality-follow-up.html)... -
arealdeveloper.com
[A Real Developer](#) is a side-project I built over the weekend poking around with [WebMatrix](http://www.asp.net/webma... -
Anonymous type equality follow-up: Equals()
After publishing [yesterday's post on anonymous type equality](https://jefclaes.be/2011/04/anonymous-type-equality.html)... -
Anonymous type equality
Let's say you instantiate two variables (a and b) using [anonymous types](http://msdn.microsoft.com/en-us/library/bb3976... -
Using C# keywords as variables
Hold it, don't shoot me. I know this would be an awful practice, but it is an interesting C\# compiler quirk nonetheless... -
Keeping WebSockets alive
The problem with using stateful connections on an imperfect place as the internet is that connections might drop. The se... -
HTML5: Exception handling with the Geolocation API
In [my previous post](https://jefclaes.be/2010/12/html5-geolocation-api-is-scary-good.html) on the [Geolocation API](htt... -
HTML5: The Geolocation API is scary (good)
I read about the [HTML5 Geolocation API](http://dev.w3.org/geo/api/spec-source.html) in the [Pro HTML5 Programming](http... -
HTML5 selectors and jQuery
In [my first post on the HTML5 javascript Selector API](https://jefclaes.be/2010/11/html5-new-in-javascript-selector-api... -
HTML5: Drawing images to the canvas gotcha
While I was playing with the [Canvas API](http://www.w3.org/TR/html5/the-canvas-element.html) I came across a weird issu... -
HTML5: More on selectors
[Last weekend I blogged](https://jefclaes.be/2010/11/html5-new-in-javascript-selector-api.html) on new addittions to the... -
HTML5: New in the javascript Selector API
Because I finally got the MCTS 70-536 certification out of the way, I can start experimenting with some fun stuff again.... -
Things good to know about SQL State Server
While installing a [SQL State Server](http://msdn.microsoft.com/en-us/library/ms178586.aspx) last week, I came across a ... -
Switching with non-constant cases in C#
Last week I came across a scenario where I wanted to switch over non-constants (aka variables), but while I was compilin... -
Handling the AggregateException
Last week I showed you how you can use the `AggregateException` to apply consistent exception handling in batch operatio... -
Exception handling in batch operations with the AggregateException
Doing batch operations and elegantly handling exceptions is a problem which every developer has faced before. In .NET 3.... -
Cannot Start Service from the command line or debugger. A Windows Service must first be installed (using installutil.exe)..
When you create a new Windows Service project and try to debug it, Visual Studio will show you a Windows Service Start F... -
Webforms lessons learned the hard way (Part 2)
If you missed part 1, you can find it [here](https://jefclaes.be/2010/02/webforms-lessons-learned-hard-way-part.html). ... -
Webforms lessons learned the hard way (Part 1)
I've been spending a lot of my days in Webforms the last two years. In this post I want to share some best practices I'v... -
Log4Net: log.Debug(String.Format()) versus log.DebugFormat()
[Log4net](http://logging.apache.org/log4net/index.html) is one of the most popular opensource logging frameworks availab... -
Response.RedirectPermanent in .NET 3.5 and older
One of the new features in ASP.NET 4.0 is permanently redirecting to a page using [Response.RedirectPermanent](http://ms...