Are you Ready for the Next Episode?
Posted by bsstahl on 2015-06-29 and Filed Under: development
While this was an interesting and somewhat novel approach, it turned out to have a few fairly significant drawbacks:
- Using this hybrid approach meant there were two runtimes that had to be initialized and operating during execution, a costly drain on system resources, especially for mobile devices.
- Applications built using this methodology would run well on Windows 8 and 8.1 machines, as well as Windows Phone devices, but not on the web, or on Android or iDevices.
So, it seems that it is time for me to move to a more standard front-end development stack. I need one that is cross-platform, ideally providing a good deployment story for web, PC, tablet & phone, and supporting all major platforms including Android, iDevices & Windows phones and tablets. It also needs to be standards-based, and work using popular frameworks so that my apps can be kept up-to-date with the latest technology.
I’ll keep you informed of my progress and let you know if this does indeed turn out to be the best way for me to build apps. Stay tuned.
Using Target-Specific Code in a Portable Library
Posted by bsstahl on 2013-06-27 and Filed Under: development
On at least 2 occasions recently, I have heard speakers tell their audience that you cannot reference a target-specific .NET library (such as a .NET Framework 4.5 library) from a Portable Class Library. While this is technically true, it doesn't tell nearly the whole story. Even though we can't reference target-specific libraries, we can still USE these libraries. We can call their methods and access their properties under the right circumstances. We can gain access to these libraries via an abstraction. My preferred method of doing this is known as Dependency Injection.
I'm going to give some quick background on PCLs and DI before getting into the details of how they can be used in this context. If you are familiar with Dependency Injection and .NET Portable Class Libraries you can skip these sections.
.NET Portable Class Libraries (PCLs)
Portable Class Libraries are .NET assemblies designed to be used by multiple target platforms in the .NET application space. You can specify which targets you want to be able to use, such as .NET 4.5, Silverlight 4, Windows Phone 8, etc. The compiler then does the work to limit the APIs you have at your disposal in that library to only the intersection of all of the selected targets. This guarantees that any code written in that library will work in all of those targets, but no target-specific (device-specific) functionality will be available. These libraries are great for business-logic and other platform-independent services but are not useable for code that requires direct access to device features like the UI, camera, GPS, etc. This code can be compiled and tested once, and then accessed from any of the selected target contexts.
Dependency Injections (DI)
Dependency Injection is a way of maintaining loose-coupling between application components. Instead of having a piece of code have a direct knowledge of one of its dependencies, the code only has knowledge of an abstraction of that dependency, usually an interface. Since the client is unaware of the implementation and only has knowledge of the abstraction, the implementation of the dependency can change, and as long as it maintains compliance to the interface, the client code is unaware of the change and continues to function normally. The correct dependency must then be "injected" into the calling code prior to being used. The client only knows that the dependency implements the needed interface, but is unaware of the actual implementation. This becomes extremely useful in unit-testing since a fake dependency such as a mock data-provider can be injected by the test context, allowing the tests to focus on the layer being tested without having to test the dependencies as well. While this is not nearly the only reason to use DI, it is an example of an excellent benefit of its use.
Injecting Target-Specific Code into PCLs
Let's suppose we have a .NET Portable Class Library that implements the business logic of our application. We want the application to be able to run on the web under ASP.NET, on Windows 8 as a Modern Windows Store App, and on Windows Phone 8. We built the PCL using these specific targets so we know (the compiler guarantees) that this code will run in any of those platforms. However, this code needs to get its data from somewhere, and that somewhere is different depending on what environment we are running in. In ASP.Net for example, we may want to get the data from Session State, or from a back-end SQL Server, while in Windows Phone 8 and Windows 8 we want to use their (different) implementations of isolated storage. We can accomplish this by defining an interface that is usable by all 3 targets in a PCL. We can then create our 3 different implementations of the storage library using target-specific code and inject the appropriate one into the constructor of one or more of the classes in the business-logic PCL. This injection can be done directly by the parent application, which is going to be target-specific so it would have knowledge of which target is needed, or it can be done indirectly using a DI Container such as Microsoft Unity.
A sample app that is available in the 3 targets previously described may look something like this. The business-logic and domain layers (interfaces, exceptions, entities, etc) are both PCLs and exist for use in all 3 targets. The UI layer and Infrastructure layers (in this case, storage) are target-specific and require a separate implementation for each target platform. A system designed in this way can maximize the use of common, shared code while still making platform specific features available in a type-safe way.
If you are interested in seeing this implementation done live, you can come to one of my Code Camp talks on the subject, or request me as a speaker for your User Group by Contacting Me.
Windows 8 Store Development for Enterprise Devs
Posted by bsstahl on 2013-02-28 and Filed Under: development
or, How I found my Passion for Windows 8 Store App Development
Update: My first Windows Store app was published on March 27, 2013.
I don't have any apps in the Windows 8 Store yet. For that matter, I don't have any apps in the Windows Phone store, or the Apple or Android stores either. I have many ideas for apps, and a number of them in the works for both Windows 8 and Windows Phone, but I have nothing real to show for it yet. Nothing to show for several years of attending sessions at conferences, user groups, and code camps on building these apps; for many hours of hacking on front-end interfaces and business logic. Don’t get me wrong, I've wanted to build these apps, but I didn't have that burning desire that I usually get when I am solving problems with software. You know that desire, the one that compels you to sit in front of a computer for hours at a time until you've completed a solution. I didn't have it.
This recently changed for me -- let me explain.
- Use portable libraries wherever possible, especially for business logic.
- Use dependency injection to make non-portable dependencies available to portable libraries. This will allow your business logic access to platform-specific functionality (such as network access) without sacrificing portability.
- Do as much of the work as possible in the underlying .NET libraries and keep the RT Component as thin a translation layer as possible. I will be exploring techniques for this in the near future. Possibilities here include making this layer either a View-Model or a Repository implementation.
I’m interested to hear if there are other enterprise developers with similar stories, whose comfort zones of HTML and C# or VB have kept them from building apps as they’d like. Please contact me on Twitter @bsstahl.
PDC 2008 - Day 2
Posted by bsstahl on 2008-11-01 and Filed Under: event development
Day 2 was a more focused day for me at PDC 2008. After attending the morning keynotes, which included the first peeks at Windows 7 features as well as a terrific (as always) code-only presentation on programming against the cloud by Don Box and Chris Anderson, I headed over to the hands-on-labs where I spent the rest of the day working with Azure and creating applications that run in the cloud. I also received my Azure key and began the process of setting up a virtual machine to house the Azure tools.
Real-Time Updates on Twitter
Just a reminder that much of what is happening here at the PDC is being posted in real-time (or close to it) on Twitter. My Twitter updates can be found @bsstahl.
Day 2 keynotes focused on the client side of Windows development. Not surprisingly, this included Windows 7 and WPF development improvements as well as Silverlight and ASP.NET development. Some things that caught my attention in the keynotes included features of Windows 7 like its ability to "live" on a domain, but still participate in a "Home Group" when your work laptop is brought home. Multi-monitor support also looks to be vastly improved including the ability to work multi-monitor in a remote desktop session. Scott Guthrie also introduced a number of new controls and tools for developing applications in WPF and Silverlight including a Ribbon control that appears intended to make your WPF apps look like Windows Forms apps.
The 2nd Keynote of the day was Don Box and Chris Anderson's fantastic presentation on developing applications that bring cloud computing into the enterprise. Clearly the most engaging of all of the Microsoft speakers, this duo put together, over the course of the 1.5 hour session, a series of services that ran both in the cloud and within the firewall, and linked the two securely, but in real-time. You would not be wasting your time if you were to view the video of this keynote online.
The remainder of my day, after lunch, was spent in the hands-on labs working through the prescriptive samples provided by Microsoft for their Azure product. I was able to complete the first two of these labs which detailed the process of creating websites and services in the cloud that used local-storage and queues to perform a number of relatively simple tasks. These labs clearly answered my question from yesterday morning, with the answer that I expected. That is, an Azure "Web Role" is a web page or SOAP service that runs in the cloud. As such, everything (that I can think of) that I might need to run on my own servers, can be outsourced into the cloud, to provide the availability of virtually unlimited scale with amazing reliability. The still-unanswered question here is price, but since the CTP is free, I will continue to move in this direction until I find a reason to change course.
Day 3 Preview
Day 3 looks to be futures day, with the keynote focusing on Microsoft Research properties and technologies. Watch Twitter for all the action as it occurs.