WinRT architecture hobbles MVVM design - mvvm

This may be too general a question, but it's causing me some lost sleep. Do the designers of WinRT either not understand MVVM patterns or are we supposed to be abandoning MVVM in favor of some other pattern? They have not only removed the DataTemplate pattern (where any POCO used in an ItemsControl or ContentControl can be automatically bound to a visual tree), but they went ahead and removed the x:Type operator as a key into the resource dictionary (e.g. "{x:Type MyObject}"). The confusing thing here is that a DataTemplate replacement is relatively trivial (many people have done this for Silverlight), but by removing the x:Type operator, they've made it impossible to even write a replacement DataTemplate search in WinRT.
So my question is, why do the architects of WinRT appear to be going out of their way to prevent us from using an MVVM pattern to build applications? Is there a better pattern that I've not yet found?

I don't think so. It's just Windows Runtime isn't mature yet, since it appeared in Windows 8, the latest version of Windows operating system.
Like any new technology, it will evolve in newer versions - or we all expect that -.
Also, think that WinRT is more than just XAML and data-binding, but a new Windows API which is aimed to replace Win32, at least in modern and multi-device development, accessible both by managed environments like .NET and also unmanaged ones like C++.
Rather than saying "they want to prevent us from using MVVM" it's more "they want to switch to a new approach to create operating system components" and it's inmanture yet.
Anyway, losing some capabilities isn't abandoning MVVM in UI development, and I'm pretty sure that future Windows versions will gradually introduce new (and not that new) features.

Related

Dapper in Metro apps

Is there any way to include Dapper in metro apps?
It relies on System.Data which is left out in WinRT.
If not is there any similar framework which can be used?
Is there any way to include Dapper in metro apps?
No. As you observe, the lack of System.Data is pretty much a show-stopper, however in addition WinRT also omits meta-programming support, so the entire core would need to be re-written to use regular (i.e. slow) reflection. There are some elaborate hoops you can jump through to get around this, but without System.Data it seems a lost cause.
Basically, the intent with WinRT (as I understand it) is to consume your data from things like web-services, the classic "smart client" rather than "rich client" model.
So you might consider:
server (full .NET)
using "dapper" for data-access
exposing some call/serialization protocol
client (.NET for Windows Store apps, or whatever the term is today)
consuming some call/serialization protocol
Strictly speaking, you can IIRC break all the rules and just reference .NET anyway, but that won't pass any MS validation, and won't be a proper metro Windows Store application.

Using Feature Toggling and IoC in lieu of Branching Code -- Good or Bad Idea?

Our clients get to choose when to upgrade. So, my team literally has to maintain and support dozens of versions of our software product. As you can imagine that results in a lot of branching and merging as hot fixes and service packs have to be propagated across all these flavors. I'm not happy with the situation. The obvious solution is simply not to maintain so many different versions of our product, but that obvious solution is not available to me. So, I'm exploring creative options to lower the team's maintenance work. I'm considering using a mix of Feature Toggling and IoC as a way to implement n-number of versions of our software product. The idea is that I could use a single code base for my product and manage behaviors and features via configuration management. This would be in lieu of having to propagate code across multiple branches. Is this a reasonable approach or am I just trading off one problem for another?
That sounds reasonable, in that this would be the way I'd address such a problem in a greenfield environment.
Let's not call it a Feature Toggle, though. As the name implies, a Feature Toggle is an on/off switch, which may not be what you need.
Sometimes, an upgrade also involves changed behaviour in existing features. That implies that you're probably going to need something more sophisticated than an on/off switch.
The Strategy pattern is a more flexible way of modelling variation in behaviour. Each Strategy can represent a particular version of a particular behaviour, and if you don't want the behaviour at all, you can provide a Null Object implementation. In other words, Feature Toggle can be implemented with a Strategy.
You can inject the Strategies into your application kernel using Dependency Injection, and you could make the choice of Strategies configurable via a configuration system. Most DI Containers I've heard about (on .NET and Java) support file-based configuration.
This essentially describes an add-in architecture.
Now, even for a greenfield application, this is no easy feat to pull off. If you have a headless system, it's not that hard, but once you have UI involved, you start to realise that you're going to need to componentise the UI architecture as well, so that you can plug in UI elements via Strategies.
On a decade-old code base, this would be what I'd call an 'interesting challenge', to say the least.

General architecture for backend?

We are trying to be forward looking in our architecture choice on some of the new systems we are designing. Pretty much we want to architecture back end system that no matter what interface we decide to use (WinForms, Silverlight, MVC, Webforms, WPF, IOS (IPad/Iphone), ect...) which i believe just screams REST. Our organization generally will only use Microsoft APIs but since i have no idea when WCF-Web-Api will be released and we want to get started soon it looks like we have no other choice.
We want to take baby steps here to increase the chances of buy off. So we don't want to have to set up another server with IIS.
In the foreseeable future we will only be using WinForms & WebForms. What i was thinking we could use Nancy on the local machine but communicate with it in a RESTFul way. That way in the future it should be as simple as setting up a server and redirecting all the clients to that server rather than locally.
I've never used either NancyFX or OpenRasta, but, from what ive heard, it sounded like a good fit.
So the questions are:
Is the way i'm thinking on approaching this a good approach
Does it sound like NancyFX or OpenRasta would be a better fit?
Any reason why we should wait for WCF-Web-API and if so does anyone have an approx release date.
OpenRasta was built for resource-oriented scenarios. You can achieve the same thing with any other frameworks (with more or less pain). OpenRasta gives you a fully-composited, IoC friendly environment that completely decouples handlers and whatever renders them (which makes it different from MVC frameworks like nancy and MVC).
I'd add that we have a very strong community, a stable codebase and we've been in this for quite a few years, we're building 2.1 and 3.0 and our featureset is still above and beyond what you can get from most other systems. Compare this to most of the frameworks you've highlighted, where none have reached 1.0.
Professional support is also available, if that's a deciding factor for your company.
But to answer your question fully, depending on your scenario and what you want to achieve, you can make anything fits, given enough work. I'd suggest reformulating your question in terms of architecture rather than in terms of frameworks.

Is MEF mature enough to bet the company on?

My company needs to rewrite a large monolithic program, and I would want it written using a plugin type architecture. Currently the best solution appears to be MEF, but as it is a fairly 'new' thing I am warey of betting the future of my company (and my reputation) on it.
Does anyone have a feeling on how mature a solution MEF is ?
Thanks
Visual Studio's entire extension system is now built on MEF.
That is to say that Microsoft is Dog-fooding it (like they are doing with WPF).
Given that the framework developers themselves will be working with it, you can feel pretty confident that it is here to stay. However, as with any first release, you are almost guaranteed to have some growing pains when the next release comes around.
Personally, I would go for it. It is certainly better than the tightly-coupled-reflection-based alternative.
I don't think it is necessary to "bet on MEF". Your code should have very little dependencies on MEF.
You can use the technique of dependency injection to break up your monolithic application into components which have only a single responsibility, and which limit their knowledge of other components to abstractions. See this blog post by Nicholas Blumhardt for a nice overview of the type of relations that can exist between components.
Wiring the components together into an application can then be done with any dependency injection framework, or even manually. The component logic shouldn't need to be aware of the container - there might not even be a container.
In the case of MEF, you do need to add import/export attributes to your classes. However, you can still ignore those attributes and reuse those components without MEF, e.g. by using another DI framework like AutoFac.
It's a relatively new technology, so I'm not sure if it's exactly mature. I'm sure it will change quite a bit over the next several years, perhaps merging with other frameworks to better support IoC. That said, MS has a pretty good history of preserving backwards compatibility, so now that MEF is actually part of the Framework, I would consider the public interfaces stable.
That said, MEF might not actually be the right solution for your project. It depends on your extensibility needs and how large is 'large'. If you want to support true extensibility, including the possibility for third-party plugins, it has an enormous impact on your design responsibilities. It's much harder to make changes to the infrastructure as you now need to maintain very stable public interfaces. If you're really only after the IoC features, you're probably better off with a true IoC framework, which more clearly limits your design responsibility to support of your internal dependencies. If you're betting the future of the company, this is the bigger question, in my mind.

Are there any disadvantages of using C# 3.0 features?

I like C# 3.0 features especially lambda expressions, auto implemented properties or in suitable cases also implicitly typed local variables (var keyword), but when my boss revealed that I am using them, he asked me not to use any C# 3.0 features in work. I was told that these features are not standard and confusing for most developers and its usefulness is doubtful. I was restricted to use only C# 2.0 features and he is also considering forbidding anonymous methods.
Since we are targeting .NET Framework 3.5, I cannot see any reason for these restrictions. In my opinion, maybe the only disadvantage is that my few co-workers and the boss (also a programmer) would have to learn some basics of C# 3.0 which should not be difficult. What do you think about it? Is my boss right and am I missing something? Are there any good reasons for such a restriction in a development company where C# is a main programming language?
I have had a similar experience (asked not to use Generics, because the may be confusing to my colleagues).
The fact is, that we now use generics and non of my colleagues are having a problem with them. They may not have grasped how to create generic classes, but they sure do understand how to use them.
My opinion on that is that any developer can learn how to use these language features. They may seem advanced at first but as people get used to them the shock of newness lessens.
The main argument for using these features (or any new language features) is that this is a simple and easy way to help my colleagues advance their skills, rather than stagnating.
As for your particular problem - not using lambdas. Lots of the updates to the BCL have overloads that take delegates as parameters - these are in many cases most easily expressed as lambdas, not using them this way is ignoring some of the new and updated uses of the BCL.
In regards to the issues with your peers not being able to learn lambdas - I found that Jon Skeets C# in depth deals with how they evolved from delegates in a manner that was easy to follow and real eye opener. I would recommend you get a copy for your boss and colleagues.
You boss is going to need to understand that language (and other) improvements are designed to give developers more capabilities, and make them more efficient in completing the task at hand, and that if he is not going to allow them for unknown reasons then:
The development team isn't producing at its greatest potential.
The company isn't benefiting from increased efficiency/productivity.
like others have said developers aren't worth their salt if they can't keep up with some of the latest improvements in the language that they are using on a daily basis. I suspect your boss hasn't done much coding lately and it is his inability to understand the latest language improvements that has motivated this decision.
I was told that these features are not standard and confusing for most developers and its usefulness is doubtful. I was restricted to use only C# 2.0 features and he is also considering forbidding anonymous methods.
Presumably roughly translates to your boss meaning...
These features are confusing for me, and I don't find them useful because I don't understand them.
Which is fairly symptomatic of the Blub paradox (well, or just sheer laziness). Either way there's no merit in what he's saying, and you should start looking for another job if he continues down that road.
If the project is strictly C# 3+ from now on, then you would not break the build by including these items. However, before using them you should be aware of the following:
You can't use them if the project lead gets to make the decision and votes no.
Other than that, you should use them where it makes the code significantly easier to maintain.
You should not use them in ways that are confusing, or unnecessary in the sense that they do not significantly improve the maintainability of the code. This does mean you should not use them where the code is effectively the same or barely improved.
If Microsoft didn't define the standard and these were features that they added to a non-Microsoft language, I would say your boss might have a point. However, since Microsoft defines the language and uses these very features in implementing significant parts of .NET 3.5 (and 4.0), I'd say that you'd be foolish to ignore them. You may not choose to use some of them -- var, for instance, may not be acceptable in all environments due to coding standards -- but a blanket policy of avoiding new features seems unreasonable.
The trickier bit is when should you start using new features, because they can be confusing and may delay development. In general, I choose to use new language features and platform elements on new projects. I often avoid using them on projects that are currently in development when the feature/framework enhancement comes out, deferring until the next project. On a long project, I might introduce them at a significant milestone if the amount of rearchitecting is small or the feature is worth the changes. Normally, I'd wait until the project is due for significant changes anyway and then evaluate if refactoring to newer features is warranted.
The jury is still out on the long term consequences of some features, but if their main rationale is 'it is confusing to other developers' or something similar than I would be concerned about the quality of the talent.
I like C# 3.0 features especially
lambda expressions, auto implemented
properties or in suitable cases also
implicitly typed local variables (var
keyword), but when my boss revealed
that I am using them, he asked me not
to use any C# 3.0 features in work. I
was told that these features are not
standard and confusing for most
developers and its usefulness is
doubtful.
He's got a point.
Following that line of thought, let's make a rule against generic collections since List<T> doesn't make any sense (angle brackets? wtf?).
While we're at it, let's eliminate all interfaces (when are you ever gonna need a class without any implementation?).
Hell, let's go ahead eliminate inheritance since its so tricky these days (is-a? has-a? can't we all just be friends?).
And use of recursion is grounds for dismissal (Foo() invokes Foo()? Surely you must be joking!).
Errrm... back to reality.
Its not that C# 3.0 features are confusion to programmers, its that the features are confusing to your boss. He's familiar with one technology and stubbornly refuses to part with it. You're about to enter the Twilight Zone Blub Paradox:
Programmers get very attached to their
favorite languages, and I don't want
to hurt anyone's feelings, so to
explain this point I'm going to use a
hypothetical language called Blub.
Blub falls right in the middle of the
abstractness continuum. It is not the
most powerful language, but it is more
powerful than Cobol or machine
language.
And in fact, our hypothetical Blub
programmer wouldn't use either of
them. Of course he wouldn't program in
machine language. That's what
compilers are for. And as for Cobol,
he doesn't know how anyone can get
anything done with it. It doesn't even
have x (Blub feature of your choice).
As long as our hypothetical Blub
programmer is looking down the power
continuum, he knows he's looking down.
Languages less powerful than Blub are
obviously less powerful, because
they're missing some feature he's used
to. But when our hypothetical Blub
programmer looks in the other
direction, up the power continuum, he
doesn't realize he's looking up. What
he sees are merely weird languages. He
probably considers them about
equivalent in power to Blub, but with
all this other hairy stuff thrown in
as well. Blub is good enough for him,
because he thinks in Blub.
When we switch to the point of view of
a programmer using any of the
languages higher up the power
continuum, however, we find that he in
turn looks down upon Blub. How can you
get anything done in Blub? It doesn't
even have y.
C# 3.0 isn't hard. Sure you can abuse it, but it isn't hard or confusing to any programmer with more than week of C# 3.0 experience. Your boss's skills have just fallen behind and he wants to bring the rest of the team down to his level. DON'T LET HIM!
Continue using anonymous funcs, the var keyword, auto-properties, and what have you to your hearts content. You won't lose your job over it. If he gets pissy about it, laugh it off.
Like it or not, if you plan on using LINQ in any situation, you're going to have to utilize some of the C# 3.0 language specs.
Your boss is going to have to warm up to them if he wants to utilize the feature sets you get from 3.5, which are numerous and worth your time investing in.
Also, from my experience in leading teams, I've found that using the 3.0 specs actually has helped devs readability and understanding of the code base. There's about a weeks worth of time that is spent by the dev trying to understand what the syntax means, but once they get it they much prefer the new way over the old way.
Perhaps you can do a presentation once a week on each feature to everyone and get some of the developers on your side to help convince management of the benefits.
I recently moved from a bleeding edge C# house to a C# house that was running mostly on dot.Net 1.1 and some 2.0 projects, using mostly only 1.1 features. Luckily management stay away from the code. Most of the developers love all the new features in the newer frameworks, they just don't have the time or inclination to figure them out by themselves. Once I managed to show them how they can make their own lives easier they started using them by themselves and we have migrated several projects to gain the new language features and better tool advantages.
Some people are just afraid of change, because maybe you'll make them all look stupid using fancy new technologies. Could also be that your boss doesn't want the team learning new things instead of getting work done the old fasioned way.
The var keyword can certainly be abused, but in most cases reduces redundant code. LINQ is the main thing you want from .Net 3.5 because of the huge time saving in the amount of code you have to write. Your boss should be encouraging you to use it. Also the base class libraries now take delegates are parameters, so you will be limiting yourself a lot by not using them. Lambda's are just some fancy syntactic sugar to make delegates cleaner.
I would refer you to Effectively Integrating into Software Development Teams and Leading by Example. Two really great articles on how to deal with teams that are afraid of change.