I was privileged to attend the IDesign WCF Master Class last week. It only comes to the USA one time each year, and is presented by the one and only Juval Lowy. The class is held at the training center on the Microsoft Silicon Valley campus in Mountain View, CA. Five very intense days of WCF covering all aspects of WCF from essentials like the ABCs to the most intricate details about advanced topics like concurrency, security, transactions, and the service bus.

What we’ve been told sold about WCF from Microsoft is truly just the tip of the iceberg. Juval presents countless examples that prove WCF is not just about web services. WCF is the evolution of .NET, providing world-class features that no class should ever be without.

Demos, samples, and labs are presented using .NET 3.5 and 4.0 with an emphasis on the new features and functionality in 4.0. Discovery and announcements are the most underrated and unknown new features of WCF 4.0. After seeing Juval’s demos on discovery and announcement, I can’t imagine creating services without them.

More than all of the WCF content, the class gives you a lot to think about regarding architecture, the framework, and engineering principles. Juval’s mastery of .NET is evident in his ServiceModelEx library that extends almost all aspects of WCF and the service bus. His “one line of code” motto makes it possible for all of us to configure our WCF services with ease. The ServiceModelEx library is a good example for all developers to know and understand how to “do .NET” the right way. It exemplifies the best of what .NET and WCF have to offer.

Check out the IDesign website to get the WCF Resource CD (containing many of the examples and demos from the class). Also note the next class dates and sign up for the IDesign newsletter.

Thank you, Mikael Sand (and Bing)!

http://blogical.se/blogs/mikael_sand/archive/2009/08/28/configuring-ws-atomic-transaction-support-in-windows-7-64-bit.aspx

The 2009 Jacksonville Code Camp was a great success. Many thanks to Bayer, Brandy, and everyone else that made it happen. The bar has been set really high for future Jacksonville code camps, and for the rest of Florida too.

My session on Transactional WCF Services went well. Many great questions and compliments after the session. If you attended and have any unanswered questions, please email me.

You can download the session files below. It contains staged versions of all of the transaction modes we discussed. It also contains a tracing solution and tracing result files to view the client and host tracing files in Client/Service mode. Also see my previous post on using the Service Trace Viewer. It also contains a few demo projects that we didn't get to in the one-hour session.

Files/Solutions included in Session Archive:

• PowerPoint slides
• Transaction Promotion Code Snippet
• Testing database backup
• Testing SQL script (query and cleanup between tests)
• IDesign ServiceModelEx Project (used by all included Solutions)
• Code Demo Solutions

Code Demos include:

1.	TransactionScope - Shows how single/multiple resource managers affect which Transaction Manager is chosen to handle the scoped transaction. Also gives first look at transaction promotion detection.
2a.	Mode None - WCF transaction mode with which no transactions are created or flowed from the calling client.
2b.	Mode Service - WCF transaction mode with which no transactions are flowed from the calling client, but a transaction is created for your service operation.
2c.	Mode Client - WCF transaction mode with which a transaction is required to be flowed, and the service will only use the client transaction.
2d.	Mode Client/Service - WCF transaction mode with which a client transaction will be flowed and used by the service, if available. If no client transaction is flowed, a transaction will be provided automatically for the service operation.
3.	Explicit Voting - Shows how explicit voting with a session-mode service is performed using OperationContext.Current.SetTransactionComplete().
4a.	Testing Various Resource Managers - Shows how a client can use a single TransactionScope to call several services (some transactional, some non-transactional), a database stored procedure, and an IDesign volatile resource manager Transactional<int>.
4b.	Testing Services - Provides a host project for a transactional service and a non-transactional service used in 4a.
5a.	Tracing - Same as 2d. modified with the additional app.config settings in the client and host projects to allow for service tracing to .svclog files.
5b.	Tracing Results - Stored results from executing 5a. in case you don't want to load the database and actually run the projects. The .stvproj file can be opened directly in the Service Trace Viewer. On the "Activity" table, click on the activity "Process action 'http://services/gotjeep.net/GpsTrackServiceContract/SubmitTrack'" then click on the "Graph" tab. You will see that the client and host activities where the arrow moves from client to host (send and receive message, respectively) show the OleTxTransaction in "Headers." The next activity in the host reads "The transaction '5bd25b08-848c-409d-9163-6303b9138382:1' was flowed to operation 'SubmitTrack'."

 

Download the session files:
TransactionalWCF.zip (854 KB)

JaxDug is doing something different this year having all sponsorship proceeds benefiting Wolfson’s Children Hospital. In addition to the sponsorship surplus going to Wolfson’s, there will also be a silent auction at the after-party at Sneaker’s Sports Grille.

There is a great session lineup with eight tracks having five hour-long sessions in each track. I’ll be presenting one session on Transactional WCF Services. It’s guaranteed to be a good geeky time, and I hope it will have record attendance this year.

 Register now!

I really like the manifesto’s web site! In the following post, MLB comments on the Open Cloud Manifesto.

http://www.dasblonde.net/2009/03/31/TheOpenCloudManifestoWhatIThink.aspx

Important, proven, and universally-useful technologies like WCF and Mobile are still not well-known in the development community. Many believe there is another boom, similar to the 1992 Internet boom, on the horizon that will require skilled and knowledgeable developers to engineer the framework and associated connecting systems. Staying tech-current and adapting to our new world is an absolute necessity. Don’t become the COBOL programmer of the future. Knowing these great system-connecting technologies (WCF, Mobile, Cloud, etc.) will quickly become a requirement to compete in the software industry.

Check out the following interview with Richard Campbell (DotNetRocks, RunAs Radio) and Juval Lowy (IDesign) talking about the EnergyNet at the DevConnections conference. The growing hype about alternative energy and the EnergyNet is stunning. Technology has progressed far enough where we can start to tie together disparate systems to benefit producers and consumers alike.

http://video.google.com/videoplay?docid=4831440850220717845

 

It’s obvious that Mr. Franklin didn’t have to deal with bad data, bad code, or even the occasional hiccup. In the real world, there is “trouble” and we need to not only anticipate that trouble, but also worry about what may never happen. Simply “keeping in the sunlight” won’t maintain data or application state integrity. In the real world we need transactions!

 

Since .NET 2.0, we’ve had the privilege of using System.Transactions.TransactionScope to manage our transactions with very few headaches. One of the headaches that almost everyone experiences is MSDTC. One of the oldest and most elusive topics on the web. There are tons of blog and forum posts directing our fellow developers to check their firewall settings for every MSDTC problem. The latest MSDTC hiccup I have seen comes in the beautifully packaged error message:

The flowed transaction could not be unmarshaled. The following exception occurred: Communication with the underlying transaction manager has failed.

The what could not be what? You can read some MSDN documentation on the topic which will probably cause you more pain. If you are seeing this error message, there’s only a few things that may be wrong.

1. MSDTC Settings
   • Check the MSDTC settings on the machine that is initiating the transaction. If “Allow Outbound” is not checked, then it won’t allow the transaction in progress to be flowed to the next machine in the transaction chain. Check the box and restart MSDTC… it should work.
2. Un-Trusted Domains
   • I have seen this error when you are trying to flow transactions between machines that are in un-trusted domains. Machines in different domains that do not trust each other block the antiquated, yet necessary, WINS resolution between the two machines. MSDTC relies on WINS resolution. I have fixed this problem before by adding host file entries on both machines pointing to the other machine. I can’t guarantee that this will work in all cases. Both of those machines are no longer under my control.
3. Imaged Servers
   • The most recent, and most blogged about problem is surprisingly caused by two machines created from the same image. Cloning or imaging servers is quite common. Building a server from scratch is not a fun activity, so we build one, create an image, and put that image on every server we want to build after that. Once again, MSDTC is standing in our way because of the way it detects the sending and receiving application’s unique identifier. Each machine has a GUID in the registry that identifies it uniquely as a participant in an MSDTC transaction. Imaged machines have the same GUID. I’ll talk about the detection and resolution of this for the remainder of this post.

Running DtcPing.exe between the two machines will actually tell you that the machines are using the same GUID. Output window text from DtcPing shown below.

DTCping log file: C:\DTC Ping\THRESHER4160.log
Firewall Port Settings:
Port:5150-5250
RPC server is ready
Please Start Partner DTCping before pinging
WARNING:the CID values for both test machines are the same
Please send following LOG to Microsoft for analysis:
Partner LOG: SCORPION6128.log
My LOG: THRESHER4160.log

Tucked away in the last step of a Microsoft Knowledge Base article titled "How to troubleshoot MS DTC firewall issues" is a reference to this problem. Use regedit.exe to look at the registry on both machines. Locate the HKEY_CLASSES_ROOT\CID key in the registry.

Find the CID key that has a description value of “MSDTC”. If they are the same, the transaction cannot flow.

WARNING: Back up your registry before making any changes!

Solution 1 - Replace the offending CID keys/values on one of the machines: In this case, you will need to find all keys/values with GUID 28b81f1c-2afb-4ee2-ad85-5bc62dad1647 in your registry and replace it with a new GUID (using GuidGen). There is likely to be 3 places this GUID appears. It is also important to note that the offending GUID appears in the DtcPing log file generated during the ping test.

Solution 2 – Use msdtc command line tool to re-install MSDTC: The commands are simply:

msdtc -uninstall
msdtc -install

After making the registry changes or running the msdtc command line tool, you must restart your server for the changes to take effect.