Nowhere near as good as Charles or FiddlerProxy, but quick and dirty debugging. Just set CF_NETWORK_DIAGNOSTICS to 3 in your scheme in XCode, then when it runs it will create a text file (the name of which is in the debug log) with all the network calls when your app runs.
I’ve just deployed my first Ruby and Sinatra app to AWS Elastic Beanstalk and it was pretty simple. One catch I did have at first was using Bundler. Everything was setup on my Mac and working fine, however once I had pushed to AWS, Passenger was returning the error:
Could not locate Gemfile (Bundler::GemfileNotFound)
After trial and error I discovered that the gemfile on my mac was named ‘gemfile’ but on my EC2 instance needed to be called ‘Gemfile’ (with a capital G). A quick rename, commit and push and Bundler worked fine.
TL;DR The Asp.net session ID in the database uses the Site ID from IIS as part of a composite key. Ensure the IIS Site ID is consistent in a web farm.
The website I work on needed to use a RadCaptcha recently on a form. Although it was configured as per the Telerik article to use out of process session state (SQL for us), it would occasionally show a grey box instead of the captcha.
After some investigation with Fiddler we found that one of the three web servers couldn’t share session state with the other two. I.e. a capture generated on server 1 couldn’t be read by server 2, but could be read by server 3. And the inverse of this was also true. Machine keys were already being shared between the servers so it wasn’t a decryption problem.
Monitoring the AspSession database watching session creation we found that server 1 and 3 were creating the same session ID whilst server 2 was creating a different but very similar ID. We saw the following IDs in the ASPStateTempSessions table in ASPState database:
3jt3wvhazn22rcliw1vyij3h2d3aafb7
3jt3wvhazn22rcliw1vyij3h2d3aafb5
After a bit of investigation I found this article which describes how the SessionID is made up of the Session ID + Application ID. The Application ID is a hash based on the AppName which is based on the metabase path of your IIS site.
As our servers run multiple sites and we’d brought these sites online in a different order, the Site IDs had got out of sync. We found the following values.
server 1 => /lm/w3svc/7/root
server 2 => /lm/w3svc/5/root
server 3 => /lm/w3svc/7/root
Server 1 and 3 AppName’s hashed to the same value, but server 2 didn’t and couldn’t therefore find the session data for the RadCaptcha.
I changed the IIS Site ID using IIS admin under Site => Advanced Settings as below and it fixed the problem. Note: this will recycle your app pool.
The site I work on fetches significant amounts of data on-demand from a remote data centre via a JSON feed. In order to provide resilience against the site being unavailable I implemented Redis on Windows as a read-through cache. (None Windows operating systems were not permitted at the time). I also implemented a refresh-ahead cache service which would ensure ‘hot’ content was always fresh.
Although the solution worked I was recently asked to look at replacements for several reasons
I chose AppFabric Caching Services from Microsoft’s for a few reasons, and within an hour or so had replaced Redis with AppFabric.
Having deployed AppFabric in a production environment for several months now, I thought i’d write a few findings:
public bool Remove(string key)
{
var dataCacheItem = _cache.Get(key);
return _cache.Remove(key, dataCacheItem.Version);
}
Overall I’m pretty happy with AppFabric, but some of these gotchas, the general lack of enthusiasm on forums etc. concerns me slightly about the future. But hey, it didn’t take long to write the concrete implementation, tests and config switches needed to get it into the codebase, so it won’t take long to replace it if it does get dropped.
In Visual Studio, choose Tools | Macro, Macros IDE, create a new module and drop this in. I bind it to Ctrl-Alt-1 for quick access.
Sub AttachToW3WP()
Dim attached As Boolean = False
Dim proc As EnvDTE.Process
For Each proc In DTE.Debugger.LocalProcesses
If (Right(proc.Name, 8 ) = "w3wp.exe") Then
proc.Attach()
attached = True
End If
Next
If attached = False Then
MsgBox("w3wp.exe is not running")
End If
End Sub
Update: 12/March/2014 If you’re using Visual Studio 2012 or newer, you will need to use the AttachTo extension.
AppFabric Cache has a max buffer size of 8MB. If you’re using the SQL Provider, you need to export and re-import the Xml configuration file to modify this. Here’s a powershell script to do it for you, building on the blog post from Javi.
Save this to UpdateAppFabricCacheBufferSize.ps1
Param([int]$maxBufferSize)
Import-Module DistributedCacheAdministration, DistributedCacheConfiguration
Function UpdateBufferSizeInConfig ([string]$configFilename, [int]$maxBufferSize)
{
$xml = New-Object XML
$xml.Load($configFilename)
$transportProperties = $xml.configuration.dataCache.advancedProperties.transportProperties
if ($transportProperties -eq $NULL) {
$transportProperties = $xml.CreateElement("transportProperties")
}
$transportProperties.SetAttribute("maxBufferSize", "$maxBufferSize")
$xml.configuration.dataCache.advancedProperties.appendChild($transportProperties)
$xml.Save($configFilename)
}
$tempConfigLocation = "c:config.xml"
Use-CacheCluster
Export-CacheClusterConfig -File $tempConfigLocation
UpdateBufferSizeInConfig $tempConfigLocation $maxBufferSize
Stop-CacheCluster
Import-CacheClusterConfig -File $tempConfigLocation -Force
Start-CacheCluster
To change your buffer size to 15MB:
powershell ./UpdateAppFabricCacheBufferSize.ps1 15000000
Two tips I gave recently to a colleague just setting out with Disqus.
Q. How do I make Disqus comments visible to Google?
A. Use the Javascript code snippet Disqus provide as this fetches the comments asynchronously. On your server implement a background task to fetch and cache recent comments from Disqus using the Disqus API (you could fetch them during page render, but your page load speed will be directly coupled to the response time from Disqus). When the page is rendered embed the cached comments between <noscript> tags. This allows you to use HTML page caching services like Akamai/Varnish whilst still having moderately fresh comments in the page for Google (and non-JS users). Best to only include a few comments to keep page size down and then provide pagination links for the search engines. (This was inspired by http://www.seroundtable.com/disqus-seo-14093.html).
If you are using an ESI caching solution you might be tempted to implement an ESI include to fetch the comments as they are dynamic content. I’d recommend not doing this as you’ll be fetching the comments (from your cache, or Disqus) on every page load which is very unnecessary just for the occasional visit by Google.
Q. What should I use for the disqus_identifier?
A. I recommend using an internal identifier for the piece of content to which the comment is attached prefixed with an environment indicator, e.g. disqus_identifier = ‘live_ 21EC2020-3AEA-1069-A2DD-08002B30309D’. I’d strongly suggest that you do not leave it blank and do not use the page URL. If you leave it blank Disqus will automatically use the URL which may not be permanent, thus when the article title changes (which is regularly included in a URL), the comments will be lost. Prefixing the environment to the identifier mitigates any clash with comments made in your testing environment when you move your CMS data around.
