MSDN Magazine - January 2009 - (Page 60)

Figure 11 Viewing Individual Persisted Instances ecution of the instance and removes it from the persistence store, which means it cannot be resumed. Finally, aborting a service instance clears the in-memory state pertaining to the given instance and reverts back to the last persistent point (which is stored in the persistence store). The Windows PowerShell Get-ServiceInstance and Stop-ServiceInstance cmdlets offer equivalent capabilities from the commandline; they provide numerous command-line options for identifying specific service instances. queued up like they otherwise would be in BizTalk Server). The way this works behind the scenes is quite simple: the “Dublin” extension simply removes all of the protocol handlers for this particular application and saves them so they can easily be restored once you are finished with the update. Once the application is offline, you can perform whatever updates are required. When you are finished with the updates and are ready to bring the application back online again, you can then select the Restore Protocols command. The Windows PowerShell Disable-ApplicationMessageFlow and the Enable-ApplicationMessageFlow cmdlets can also be used to perform these same tasks from the command line. Businesses also need the ability to monitor running applications in order to see how the business is functioning and what changes might be necessary. The WCF and WF runtimes already come with a built-in tracking infrastructure that the “Dublin” extensions build on, making it easy to enable monitoring within your WCF and WF applications. There are two main players in the .NET Framework 4.0 trackUpdating Running Applications ing architecture: tracking profiles and tracking participants. DeOne of the particularly troublesome aspects of working with real velopers define tracking profiles that tell the runtime what events systems is the need to periodically update them. to track, and then tracking participants can subFor most complex distributed applications, this scribe to those events. can be tricky to do correctly when the necessary “Dublin” comes with some built-in tracking changes require updates to the database, business profiles that make it easy to track to a common logic, and service code simultaneously. Usually, it’s set of useful events. You can easily enable tracking not possible to apply significant updates atomically for your application by navigating to a particular while the application is running. service in IIS Manager and selecting Tracking in One way to approach this problem is to take the the right-hand pane. application offline while you are performing the Then you’ll see the dialog shown in Figure 12, update. However, if you really think about it, there’s which allows you to configure some basic trackFigure 12 Configuring Basic not an easy way to take an IIS/WAS application ofing capabilities for your workflows and services. Tracking fline while simultaneously performing an update Once you’ve configured this, the appropriate upto a Web site. This is another area where the “Dublin” extensions dates will be made to your configuration and the WCF/WF trackadd value through a simple offline feature. ing infrastructure will kick in. You can select an application in the IIS Manager and then select If you would like, you can also view tracking data through the the Disable Protocols command in the right-hand pane shown in “Dublin” extensions. You can select View Tracking Data while inFigure 8 (it is important to note that this will likely be renamed specting persisted service instances (see Figure 11), which will in a future release). Doing so causes all instances of the applica- run a SQL query against the monitoring store to produce a list of tion’s services to end in a blocked state or to finish their execution tracking events for you to view (see Figure 13). When you want naturally, without allowing any new incoming requests to be pro- to track custom events, you can define custom tracking profiles cessed in the meantime. and configure them through the Tracking Profiles option on the At this point you have basically stopped the message flow for main IIS Manager view. this application, meaning that clients will no longer be able to I don’t have space to cover all of the “Dublin” features here—there send messages to services without receiving errors (they won’t be are several other compelling features that merit further discussion 60 msdn magazine .NET 4.0 and “Dublin” Monitoring Running Applications

Table of Contents Feed for the Digital Edition of MSDN Magazine - January 2009

Toolbox CLR Inside Out Basic Instincts Cutting Edge Test Run First Look� Geneva Framework Silverlight Windows Mobile Service Station Security Briefs Extreme ASP.NET Foundations .NET Matters { End Bracket }

MSDN Magazine - January 2009

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