In our latest release, we are taking advantage of the new AppFabric Caching Service to host our session state. AppFabric provides fault-taulerance for session data within our web server farm. However, the AppFabric cache servers were crashing every hour or so in our QA environment with the following exception:
AppFabric Caching service crashed.{Lease with external store expired:
Microsoft.Fabric.Federation.ExternalRingStateStoreException: Lease already expired
at Microsoft.Fabric.Data.ExternalStoreAuthority.UpdateNode(NodeInfo nodeInfo, TimeSpan timeout)
at Microsoft.Fabric.Federation.SiteNode.PerformExternalRingStateStoreOperations(Boolean& canFormRing, Boolean isInsert, Boolean isJoining)}
The environment is configured with 2 Windows 2008 R2 Data Center 64-bit VMs (4GB ram each) running the AppFabric Caching service. The caching configuration
is stored in a SQL Server 2008 R2 database.
The cache was created with the following PowerShell command:
New-Cache -CacheName SessionStateCache-1 -Secondaries 1 -TimeToLive 20
After much head scratching and discussion, I finally hit upon the answer: the time between the servers was slightly off. The cache servers had a 2 minute time difference between that of the database server. Apparently this difference is large enough to cause serious problems. Our cache servers were pulling their time from Active Directory, while the database server had been misconfigured and was pulling its time from the VM host. This was easily fixed by changing the setting within the VMWare tools on the database server. Once this change was made, the crashing stopped & the cache has been running solid.
This is just another example of how critical the alignment between clocks has become. I had a similar (but different) problem with my son's iPod touch. It stopped playing videos on YouTube & Netflix. Connectivity was fine, but somehow his clock was set back to the beginning of time. Once I set the clock correctly, all was well. You can have similar problems with SSL if your system clock isn't set correctly.
So, if you're having unexplainable problems, check your system clock.
The new desktop integration features of IE9 are great. However, I have a few thoughts on how they could be improved.
Icon Integration
IE9 lets you pin your site to the taskbar and it places your site's icon on the taskbar & the IE9 window. But, what if a site your using doesn't have a favicon? Here's an example: the C# Help web site. It doesn't have a favicon, so you get the default IE logo.
That isn't terrible, but if I pin multiple sites that don't have a favicon, I end up with lots of IE logo icons. Which is which? There is no way to tell. And, there is no way for the user to customize the icon that is displayed. Shortcuts support this, but pinned sites don't. This is a problem.
This could be easily corrected if there was a icon selection dialog for the end user. This would allow the user to put unique icons on their sites...regardless if the site was built with this feature in mind.
Jump List Integration
Another desktop integration feature is the Jump List. If a site doesn't have the appropriate metatags, then you get the very basic jump list.
It would be super cool if I could customize the jump list. What if I could add bookmarks to the jump list? This would allow me to easily visit different parts of the site.
So Microsoft, what do you think? IE9 is still in beta...there is still time. Go for it!!
I've been using Internet Explorer 9 for a few days now & I really like it. The browser has a very clean UI...most of it is similar to what has been seen with Chrome & the latest Firefox browsers. As you've also probably already heard, it is pretty fast and standards compliant. It looks like Microsoft is finally serious about making a good browser.
They've also added some innovative hooks into the browser to allow tigher integration with Windows 7. Read this article on MSDN to see how your site can take advantage of this functionality.
Some web sites are already taking advantage of it. Here is a customized jump list provided by Amazon.com.
And this is just the beginning...there are thumbnail toolbars, icon overlays, notifications, and more.
As the desktop & web continue to merge, this functionality is a nice touch.