Brennan’s Blog

On Tuesday Brian Morgan of Skyline Technologies will cover Lessons Learned Implementing Service-Based Applications at the .NET User Group meeting. In other words, this presentation will cover SOA. The term SOA has been used and abused heavily the past couple of years in relation to Web Services which is also heavily abused. In the context I have come to accept SOA means Service Oriented Application (and occasionally Architecture) which allows components to be directly or remotely connected by simply adjusting the configuration to suite the desired deployment scenario.

SOA with .NET means Windows Communication Foundation (WCF) which is a rich implementation of the WS-* specifications such as WS-ReliableMessaging. This is a timely topic for me as I have been preparing to make use of WCF for a few projects. I do not know the details of what is going to be presented, but I am certain they will review the common misconceptions of networked applications with network latency being one of the primary issues.

But network latency is just one problem which may never actually enter the scope of your distributed application. With a self hosted or even closely hosted service you may never leave the same machine when talking with a service. With named pipe or TCP binding you could be communicating directly with a service on the same computer without any interference or lag which is introduced with an external computer.

I am also interested in the availability of the disconnected services. When I simply use classes which are held in a third party assembly I always have access to them, but a service may go offline or somehow become unresponsive. I expect reliability and availability to to be a significant issue. The best way to host a new WCF service is with IIS7 inside of the Windows Process Activation Service (WAS) but it is only available with Vista, a desktop OS that limits the number allowed connections. The only real option is hosting your services with other means on Windows Server 2003, such as using IIS6 or creating a custom Windows Service. I am very interested in what Morgan chose for hosting services and what problems he encountered and hopefully resolved.