Orcas Workshop: Day Three

Three days down, one to go. There was a great presentation on WCF (Windows Communication Foundation) today! I'm really impressed with some of the stuff they provide out of the box for free. They also talked about WF (WorkFlow) and mobile devices.

WCF

• Microsoft says that WCF is the next generation platform for building distributed systems (and I haven't even gotten the chance to use the last generation platform).
• WCF provides the infrastructure to hook up any number of different protocols to a published service. This can be SOAP, REST, or any number of different protocols (there are a lot of them that WCF understands).
• End points are essentially the transport layer for calling a service. A single service can have multiple end points defined for it (so it can be called using SOAP, REST, etc). The developer does not have to write any code to hook up these end points, it's handled by WCF. The end points can be created in a post-deployment scenario using configuration files.
• 3.5 offers a lot of new features such as better tooling support for building and debugging services. There is a service host similar to the ASP.Net debugging host that will run so that you can test your services without having to setup your own server. There is also a WCF client that will allow you to call any of your services, including setting parameters and viewing return values. This will allow you to set break points in  your code and debug into it. These should be available in the beta 2 (I don't believe they are in the beta 1).
• 3.5 includes 1st class support for REST, syndication, JSON (JavaScript Object Notation), Oasis, and WF (I'm sure I'm missing a bunch!).
• There is an SDK available for syndication that I believe will run using the 3.0 bits at http://labs.biztalk.net. The name of the SDK is BizTalk Services SDK. You should be able to just reference the assembly that exposes the syndication library in order to use it (sorry, I don't remember exactly which one it is).

WF

I didn't find this presentation as interesting because I already know something about it and it doesn't look like they are adding much for 3.5.

• WF is the software implementation of the business process or business logic.
• WF is a lightweight process (as compared to other workflow services available)
• Provides the infrastructure for maintaining state over a long running process.
• A workflow can be a flow chart, state diagram, or rules based.
• WF can be built using either code or markup
• 3rd party designers available for designing workflows and saving as XML
• Context Exchange Protocol allows for long running workflows. This works on a similar concept as cookies so that the workflow instance can be re-constituted when new events arrive.
• WF provides static role based authorization as well as dynamic (code based) authorization.

Mobile Apps

There seems to be a lot of cool new features for mobile devices within the Orcas time frame, especially for developers.

• The designer surface in VS08 can be made to look like the mobile device that you are targeting.
• The emulator starts quickly once you have saved the state (otherwise it has to load tons of stuff when you start it).
• You can create unit tests the same way as you would any other project in VS08. The emulator contains the testing framework. When you run the unit tests, the emulator starts and the unit tests are loaded onto it and run.
• The emulator can be easily configured using XML to test different deployment scenarios such as RAM, screen resolution, screen orientation, battery level, etc (I'm sure you get the picture).
• There is a device configuration manager built into VS08 that allows you to change the security context of the device.
• If you want to connect to devices from a desktop application, you can use the Microsoft.Smartdevice.Connectivity.dll. This will let you discover any devices connected to the computer and connect to them.

Compact Framework

• In order to make the compact framework fit on the device, many features had to be removed. This includes many libraries that weren't that useful on the device (such as the ASP.Net assemblies) as well as removing many classes and class members from the ones that were left. The end result is around 6MB.
• Version 3.5 of the compact framework will include WCF capabilities, however, in order to meet the size requirements, much of the WCF was stripped out. This makes it more difficult to use WCF on a mobile device, but at least it's still possible.
• 3.5 will be supported by all devices that support 2.0. You will just need to deploy the 3.5 piece.
• Due to the occasionally connected environment and the stripped down version of the WCF, the compact framework uses email to provide reliable transport of messages.
• 3.5 will support LINQ, but not all implementation of it. LINQ for SQL and LINQ for entities will not be supported. Expression trees are also not supported (the compact framework doesn't support Reflection.Emit which is used by expression trees).
• There will be a remote debugging tool made available that will make it easier to find memory leaks on a device.