Your starting a new web project and you want to use sass/less for css and require.js for javascript dependency management. Maybe you want to use jslint/jshint to verify your javascript syntax and csslint to verify your css. To make this a smooth developing experience you want to run a background file watcher that runs tasks whenever you change a file.

So when you modify a javascript file, all js files are verified for syntax, require js optimizer is executed to traverse your dependency tree (and spits out combined files). Maybe javascript tests are executed on the fly as well. Same thing when you modify a sass file you want the generated css to be created behind the scenes automatically.

I have used psake (Powershell build script framework) for almost all my build scripts lately. I am not a big fan of Powershell, at least the Powershell syntax. But psake makes writing build scripts a lot easier than msbuild ever has.

I wrote a little powershell utility function that sets up file watchers that when triggered executes a psake task.


task Watch {
	WatchFiles "$scripts_dir" "*.js"  "JsCheck"
	WatchFiles "$touch_test_proj_dir\JavaScript" "*.js"  "JsCheck"
	WatchFiles "$styles_dir" "*.scss" "Sass"

Whenever a js file is modified in the scripts folder (or subfolders) execute psake task JsCheck (this task will run jshint, require js optimizer, and javascript tests).

Here is the gist for the WatchFiles function:

The only trouble I had was dealing if duplicate events, the .NET file watcher class is a little buggy, generating duplicate file changed events which required a little hack to filter them out.

There are many file watchers for node / grunt but I found them a little buggy and CPU intensive. And by using powershell and a regular .NET file watcher does not block the console, you can still use the Powershell console that is running the file watchers.






Another thing that is very nice to have when you run background tasks is notification when things go bad or good. This is where Growl for Windows is handy. If a powershell psake task throws an exception I can call growlnotify like this:

function growl($title, $message, $icon) {
   if (Test-Path "C:\Program Files (x86)\Growl for Windows") {
      $iconUri = ([system.uri] "$base_dir\build\images\$icon.png").AbsoluteUri
      Write-Host $iconUri
      & growlnotify /t:$title /i:"$iconUri" "$message"

That way you instantly know when you have missed a comma, broke the code style guidelines, wrote the wrong require js dependency path etc.

I have been spending a lot of time thinking about and playing with Metrics. It started as an innovation project at my current customer but I have had a hard time not to think and work on it on my spare time.
It all centers around a small metrics framework that pushes application performance timing, health, and most importantly business counters and metrics to a backend system called Graphite. Graphite is a real time scalable graphing system that can handle a huge amount of metrics. You can define flexible persistence and aggregation rules, and most importantly you can plot your metrics in graphs using a large amount of flexible functions. Functions that can combine metrics, stack metrics from different servers, calculate percentiles, standard deviation, moving average, summarize, filter out outliers, etc.
I wrote a small metrics framework that can handle counters, gauges and timers. These are aggregated and sent to Graphite via UDP every x seconds (depending on how real time your want your metrics).
Examples of how to increment a counter and time a lambda function. The real power comes from how graphite can aggregate metrics from all production servers, compare or summarize them.

 aliasByNode(test.servers.*.gauges.cpu.processor_time, 2)
With a single line like this we can stack cpu usage on all test servers (notice the wild card in the above expression). New test servers would automatically appear in the above graph.
You can also aggregate metrics from different servers like this:
Graphite gives you a lot control of how to persist and aggregate metics in the backend as well.
pattern = ^prod.*
retentions = 10s:6h,1min:7d,10min:5y
This translates to: for all metrics starting with 'prod' , capture:
  • 6 hours of 10 second data
  • 1 week of 1 minute data
  • 5 years of 10 minute data
In another config file you specify how metrics should be rolled up (for example how 10 second data should be rolled up / aggregated to 1 minute data). For example you want counters to be summed, and timings to be averaged.
You can also have a graphite aggregator that aggregates and persists aggregated metrics. For example most of the time you don’t want to see business metrics split per server so to make it easier to plot graphs you can have graphite create and persist an aggregated metric for you (this could be done by graph functions as well). This is can be done using format rules like this:
<env>.applications.<app>.all.counters.<metric_name> (60) = sum <env>.applications.<app>.*.counters.<metric_name>
Given metrics with names like:
Graphite will every 60 seconds summarize the counter received for each server and generate a new metric with name name “all” instead of the server name.
Graphite is bundled with a web application that lets you view and create graphs and dashboards (shown in the first screenshot in this blog post). The standard graphing component utilizes image based graphs. There is an experimental canvas based graph as well but it is not very good. Luckily there are a great number of alternative frontends for graphite that support live graph dashboards that use canvas or svg graphics. I like Giraffe, but its styling was not very nice, so after a quick css makeover it looked like this:  
With Giraffe and other svg/canvas based dashboards and graphing engines you can get real time moving graphs (graph data is fetched from graphite HTTP API).
There is a large community built around Graphite, with everything from metric frameworks, machine metric daemons, alternative frontends, support tools and integration with monitoring systems like Nagios and Ganglia.
Graphite is not easy to install and setup (do not even try to get it running on windows). And it takes time to understand it’s persistence model and configuration options. It is extremely specialized to do one thing and one thing only: persist, aggregate and graph time series data. This specialization is also it’s strength as a single Graphite server can handle millions of metrics per minute and store them in a very optimized format (12 bytes per metric per time interval). So 6 hours of 10 second data is just 2160 bytes per distinct metric.
Lets say you have 10 servers with 2 applications, each application sends 200 distinct metrics (business counters, performance timings, operation metrics, etc) every 10 seconds. The storage required for 6 hours of data: 10 (servers) * 2 (applications) * 200 (distinct metrics) * 6 (measures per minute) * 60 (minutes) * 6 (hours) = 8640 KB
Metrics older than 6 hours will be rolled up into one minute buckets which will reduce storage to 1/6th of the above.
Update (2014-02-23): 
I have since this post created a new graphite dashboard replacement called Grafana, visit for more info!. 

I have been working a lot with node.js lately and some Nancy (low weight .net web framework). I love how explicit they are in the HTTP interface you define and how they allow you to structure your application as you find appropriate (for example around features or feature groups).

Node.js example:


Nancy example:


They give you full control how you structure and organize http handlers (code, folders, view locations). So when I now started a new ASP.NET MVC project I am struck by how awkward I find the default mvc folder structure and url –> controller routing mechanism.

Default ASP.NET MVC project folder structure:


Having Controllers, Models and Views in the root folder feel strange to me, they are basic building blocks in mvc projects and have nothing to to do with features or the application domain. ASP.NET MVC has support for areas which allow you to organize your code around application domains or features but the default controllers and views cannot be in an area folder. Try for example to have an controller in an area be your default route and it will be looking for views in the default root view folder.

Luckily MVC is extensible enough to partially solve this. We can move the default controllers, views and models into a “default” area folder, this won’t really be an area in the same sense as other areas. Because we will trick ASP.NET MVC to look for “no area” views and controllers in this folder instead.


By removing the standard Razing engine and instantiating a new we can modify the view location formats to make razor look for views for the “no area” routes/controllers in the default folder inside the areas folder. Now we can clean up the root folder structure.


This feels so much better, we can have default views and layouts in the default area folder, maybe a few controllers but preferably every controller should be placed within an area (feature / feature group). I still find the url –> controller action routing obstructing the clarity and simplicity of HTTP, but it has it uses. Also the whole area feature in ASP.NET MVC feels tacked on and not well implemented as they complicate all url routing and url generation. When using areas Url, Action and Form helpers need to be told which area the controller you are referring to resides.


This can be overcome by using smart lambda based (typed) helpers: 


But sadly no such helpers come included in vanilla ASP.NET MVC (they did/do exist in MVC Futures and MVC Contrib if I remember correctly). Anyway after this small change I feel a little better using ASP.NET MVC, still miss node.js though.