DotNetSlackers Latest ASP.NET News in Category Patterns and Practices

Common Design Patterns Presentations

Steven Smith — Thu, 17 May 2012 00:00:00 GMT

This month I presented on Common Design Patterns at two regional events. Ive given this talk a few times before, and it continues to evolve. The first one was on 4 May at Stir Trek, as a replacement talk for a cancellation. I only had about 24 hours notice so I didnt spend much time updating the talk, and in fact I had to rip out a bunch of stuff that was specific to the last event I gave it at or outdated information, so visually the slides at Stir Trek werent what I would consider up to par. The second time I presented was last night at MIGANG in Michigan, and I had a chance to give the slides a bit more love and choose some appropriate imagery to support the concepts. You can view the slides from the presentation (the second one) here:

Common design patterns (migang 16 May 2012) View more presentations from Steven Smith.

The presentations demo code is actually a fork of the MVC Music Store sample available on CodePlex. You can download it as a zip or via Mercurial from the MvcMusicStoreRepositoryPattern fork here.

I did realize after talking to a couple of attendees last night that at one point I mentioned that the Design Patterns book was by Fowler. I meant Gang of Four. If youre looking for good books on the patterns I discussed, and others, here are some good ones:

Design Patterns reference by Gang of Four
Head First Design Patterns great learning book, highly recommended
Patterns of Enterprise Application Architecture more patterns for use in enterprise applications by Fowler
Domain Driven Design builds on and introduces additional patterns
Refactoring reference by Fowler
Working Effectively with Legacy Code in my opinion this shows better how, when, and why to refactor code than Refactoring does

And of course if you want to learn Design Patterns and the Principles of Object Oriented Design that they follow, youll find great Pluralsight courses on these topics.

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Doing Your First Mock

the telerik blogs — Mon, 14 May 2012 00:00:00 GMT

Are you looking for a solution to your unit tests modifying data? Perhaps your unit tests are so slow that none of your teammates bother running them? You need mock objects.

The following items will be covered to help you write better tests:

Why Mocking how mock objects help you
Real World Example an example of code to be tested
Testing the Example how to use mocking to test the example
AAA Pattern a pattern emerges when writing clean tests

Why Mocking?

Mocking is one of the most important factors in writing better unit tests. It drastically minimizes a tests execution time and gives you an upper hand in validating complex logic without disk, database or service dependencies.

Mocks are more than the default-valued objects known as stubs. Mocks act as collaborators and are subject to behavioral modification. These collaborators will help you achieve your desired unit-testing goal for a given system and a controlled set of inputs. This is achieved by having the mock object stand in for the real object and returning data you have specified.

To get a complete overview of mocks, an informative article named Mocks arent stubs by Martin Fowler is a must read.

http://martinfowler.com/articles/mocksArentStubs.html

After you are finished, its time to give you a good grasp of mocking with a real world example.

Real World Example

I am going to implement part of a banking system. This includes the transfer of funds between two different currency accounts using the currency converter service.

To begin, I have created an ICurrencyService interface:

public interface ICurrencyService { decimal GetConversionRate(string fromCurrency, string toCurrency); }

This service interface will be injected to an AccountsService class that is responsible for the transfer funds operation. Once the source and destination account objects are passed to the operation, it will then withdraw from source, convert the currency based on current rate, and finally deposit the converted amount to the target account. There will be a check for available balance, authorization, approval, etc. in more complex scenarios, but they are out of scope for this article.

public class AccountService : IAccountService { private readonly ICurrencyService currencyService; public AccountService(ICurrencyService currencyService) { this.currencyService = currencyService; } public void TransferFunds(Account from, Account to, decimal amount) { from.Withdraw(amount); decimal conversionRate = currencyService.GetConversionRate(from.Currency, to.Currency); decimal convertedAmount = amount * conversionRate; to.Deposit(convertedAmount); } }

Testing the Example

The goal is to validate or assert the transfer funds operation between two accounts. Therefore, this is the system under test (SUT), and the currency service is the collaborator which will be mocked. I am using JustMock for this purpose, but the core concept is the same with other mocking tools.

Arrange

First I will create the mock of the ICurrenyService interface:

ICurrencyService currencyService = Mock.Create<ICurrencyService>();

From the account service implementation, I can see that GetCurrencyService is being called to retrieve the conversation rate. The next step is to set an expected return value for it.

Mock.Arrange(() => currencyService.GetConversionRate("GBP", "CAD")).Returns(2.20m).MustBeCalled();

Mock.Arrange is the entry-point for setting expected behavior for a given mock. This line is self-explanatory, but I did use one extra option: MustBeCalled. This ensures that if currencyService.GetConversationRate is not called with the above criteria, then it will fail the test.

Since I have finished setting the behavior, I will then create an instance of the AccountService class followed by the source and destination Account classes.

var accountService = new AccountService(currencyService); var canadianAccount = new Account(0, "CAD"); var britishAccount = new Account(0, "GBP");

Act

Next, I will add some money into the GBP account:

britishAccount.Deposit(100);

Then transfer it to my Canadian account:

accountService.TransferFunds(britishAccount, canadianAccount, 100);

Assert

Once the transfer is complete, I need to make sure the operations happened as expected. I will first assert the balance of the two accounts:

Assert.AreEqual(0, britishAccount.Balance); Assert.AreEqual(220, canadianAccount.Balance);

Then I will assert the mock to verify whether the required GetConversationRate method is called as expected:

Mock.Assert(currencyService);

AAA Pattern

You may have noticed that there were three easy steps involved with the unit test. This is part of a well-known pattern called Arrange Act Assert or AAA. JustMocks syntax is implemented to strictly follow the AAA pattern to give you a well-structured flow, even in the most complex scenarios.

In this post, I described how mocking will help you. I then built an example project and test to illustrate how to proceed. Mocking helps you write clean unit tests, and it enables you to focus on the test logic by isolating external factors. With mocking, unit testing is no longer a chore.

About the author

Mehfuz Hossain

Mehfuz works as the Team Lead at Telerik focusing on JustMock. He is passionate playing around with the latest bits. He has been a Microsoft MVP, author of OS projects like LinqExtender and LINQ to flickr. Prior to working at Telerik , Mehfuz worked as a core member in many high volume web applications including Pageflakes that is acquired by Live Universe in 2008. He is a frequent blogger and was also a contributor and site developer at dotnetslackers.com. He is a firm believer of openness and currently enjoys his free time with objective-c and nodejs bits and never minds writing in textmate.

@mehfuzh

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WPF x FileExplorer x MVVM

The Code Project Latest Articles — Sun, 13 May 2012 00:00:00 GMT

This article describe how to construct FileExplorer controls included DirectoryTree and FileList, using Model-View-ViewModel (MVVM) pattern....

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Designing a Windows 8 Metro style app starting from an existing Windows Phone app Design Case Study Part 1

the telerik blogs — Thu, 10 May 2012 00:00:00 GMT

A lot of the Windows Phone developers out there are already considering porting their Windows Phone apps to Windows 8. May be you are thinking: from Metro to Metro - it has to be pretty easy and straightforward, doesnt it? Lets see if this is true.

This case study gives insights into porting the design of an existing Windows Phone app to a Windows 8 Metro app. It discusses the main similarities and differences between the design guidelines of the two platforms, what can and cannot be reused.

User Experience Design Guidelines for Windows Phone

User Experience Design Guidelines for Windows 8

For the purposes of the case study we are using Tasks - a free Windows Phone todo lists app with more than 100,000 downloads. The app was created by the Telerik Windows Phone team as a showcase of our UI components for Windows Phone. It started originally with an app called ToDoLists, which is meant to serve as a learning material for Windows Phone developers (the source code is freely available and can be downloaded from here.

We will touch upon all the key design patterns and processes that are part of a Metro app and comment on what makes Windows Phone and Windows 8 similar and different:

Design process
Layout and navigation
Commands and actions
Touch
Orientation and views
Notifications and live tiles
Telerik upcoming Windows 8 suite

This is the first part from series of two blog posts where we will talk about the design process and layout and navigation. You can download the full series as:

high resolution pdf (~7 MB), or

low resolution pdf (~2 MB).

Design process

Before we even get to the rough design concept, no matter which platform we are targeting, we start with research, thinking about what users need and analyzing existing applications across all mobile platforms. In our case we had the initial information architecture sorted out in Tasks for Windows Phone. On this solid base we started improving it and make it work for all the screen sizes.
This is how the low fidelity wireframes looked at this phase sketches of ideas, different pages of the application which formed the application flow and the early paper application prototype. The next step was increasing the wireframes fidelity and transferring them from paper to file.

Paper wireframes

The developers participated in every step of the design process, helping with ideas and technical knowledge. They started working on the prototype of the app simultaneously with me working on the visual design. This does not mean that my job was done once the visual design is delivered on the contrary. A serious designer input was needed when all the functionality was put together. Only then, especially with touch, we can be sure everything is in the right place, the interaction is consistent and feels natural. Stick to the agile best practices and have as many iterations as needed with the developer team and your testers, if you have such.

My advice is to start working on the device as soon as possible. Once youve started working on the device dont be afraid to make all the necessary changes in order for the app to work at its best. And remember, do not fall in love with the design or the feature which just wont work.

Application flow diagram one of the deliverables at the end of the design process

The Layout and navigation model of Windows Phone and Windows 8 are very similar and different at the same time. Lets first look at some of the things the two platforms have in common:

1. Navigate through content

Content not chrome is one of the essential Metro principles and it applies to both the Windows Phone and the Windows 8 Metro app: they have the same hub and spoke navigation models. Here they are:

1.1. Hub page or the home page of the application from where the user reaches the rest of the application content. The goal of the hub page is to show the variety and richness of the content the application provides. It is like a magazine created for the application. In Tasks we show excerpts from due tasks, projects and categories.

Tasks for Windows 8 hub page

Tasks for Windows Phone hub page

1.2. Section pages these are pages with identical content type. For example All Tasks page.

Tasks for Windows 8 section page Tasks for Windows Phone section page

1.3. Detail pages the name speaks for itself a page that show the details of a single item.

Tasks for Windows 8 details page Tasks for Windows Phone details page

Now lets examine the differences between the Windows 8 and Windows Phone design patterns.

2. No hardware back button in Windows 8

Software back button in Windows 8

Windows 8 has no hardware back button as opposed to Windows Phone, which results in the need for a back button in the page heading or navigation bar. The back button takes the user back where she came from and all pages but the hub page should have it.

In Windows Phone the Backstack is very important this the list of pages/steps user went through till the current moment. The Backstack should be carefully managed the user must not get lost in the application, fall into traps, loops, and phantom pages, because only in that way she will thrust the application to get her back where she wants.

I will give you an example for that. In Tasks for Windows Phone it is possible to pin a task (project, category) to Start menu. When the user taps on pinned task a details page is opened. To continue browsing in the application the user should tap on the home button close to the logo. When the user is in the home/hub page the details page is removed from the Backstack. The reason is to fulfill the requirement for publishing apps in the marketplace - when the user is on the home page and hit the back button she should go back to start.

In Windows Phone the user navigates through the app by tapping on the content items and application buttons, and goes back with the back button.

In Windows 8 the user has more opportunities to choose her way.

3. Navigating with the edge swipe

Swiping from the edge of the screen is what makes the app bar and navigation bar to appear. The Navigation bar provides global navigation controls - it shows on every page and provides consistent navigation experience. The Navigation bar in Tasks for Windows 8 is one of the main differences from the Tasks for WP. We chose to use it as addition to the already implemented navigation model because of the confidence it gives to the user to go everywhere she wants from any page of the app.

Navigation bar

4. Page filters and sorts

The pivot control is the Windows Phone way to manage views and pages within application. It is used for filtering the content, viewing multiple data sets or switching views. In Windows 8 the pivot control is replaced with page filters and sorts. It is pretty much like traditional tab pattern.

Tab control in Windows 8 Pivot control in Windows Phone

5. List menu navigation. Filter menu.

This is the advantage of the bigger screen to have a menu which is made from items of certain type alongside the detailed page of the selected item. Even better, instead of making this menu list long and unreadable, there is a filter available on top to help for easier access to the desired information. This is almost impossible on the smaller phone screen to have both the detailed information and the available other choices on same place. It is not applicable in all cases, but in our Tasks app it was more than welcome.

List menu with filter in Windows 8

6. Horizontal/vertical scrolling

The other significant difference between Windows Phone and Windows 8 is the way of handling the scrolling. In the Windows Phone panorama control there could be both horizontal within the panorama, and vertical within the listboxes in the panorama. In Windows 8 this situation is not recommended. There could be only horizontal or only vertical scrolling. The reason for that is the cross-slide interaction sliding the finger a short distance, perpendicular to the panning direction to select an item. There should be consistency of the selection interactivity within single page thats why the panning direction should be only horizontal or vertical.

7. Semantic zoom

Semantic zoom on the home page

Another element that needs to be designed in Windows 8 is the semantic zoom - a quick way to zoom out to groups of content and jump to the desired one.

8. Settings, sharing, about, feedback, search - with charms

Windows 8 provides for a special place to put all these pages and they are neatly organized. They are called charms and are just an edge swipe away. I must admit that in Windows Phone Tasks these pages are not so well organized but in Windows 8 they will be.

Feedback flyout

Tasks for Windows Phone is available for free on the marketplace. Check it out here

Tasks for Windows 8 is on its way and we will let you know once its live.
Tasks for Windows Phone is built with RadControls for Windows Phone UI components and building blocks for building Windows Phone apps. Read more here and download a free trial.

Stay tuned for part two where we will take a look at commands and actions, touch, orientation and views, notifications and live tiles and Telerik upcoming Windows 8 suite!

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YourKit Profiler 7.0 for .NET

ASP.NET Announcements — Fri, 04 May 2012 00:00:00 GMT

Greetings, YourKit, LLC is glad to announce immediate availability of YourKit Profiler 7.0 for .NET released on April 19, 2012. It can be downloaded at http://www.yourkit.com/dotnet/download/ MOST NOTABLE CHANGES AND NEW FEATURES:============================== ======== - Running profiled applications has been totally reworked, improved and simplified. Each type of profiled applications now has a dedicated control on the Welcome screen. - CPU tracing overhead dramatically...

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International Code Sharing

JohnPapa.net — Fri, 04 May 2012 00:00:00 GMT

A Swede, and Italian/American, and a Ward Bell walk into a bar OK, so I dont exactly know what Ward Bell is (besides a great friend and brilliant colleague). And whats he doing walking into a bar with a Swede? And how did they do that since Ward lives in San Francisco, CA and Hans Fjllemark lives in Sweden? And why did they invite me, the Italian/American, since I dont drink? They went to the bar to share code ideas, of course! Ive always enjoyed working on side projects with friends so I could...

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Folien zum UI/UX-Vortrag in Bielefeld online

Roland Weigelt — Fri, 27 Apr 2012 00:00:00 GMT

Mein Vortrag am 25.04.2012 in Bielefeld ist auf reges Zuschauerinteresse gestoen, der Raum war wirklich gut gefllt. Und es hat mich auch sehr gefreut, wieviel positives Feedback ich in den Tagen danach per Email sowie ber Twitter und andere soziale Netzwerke erhalten habe. Die Folien zu stehen nun zum Download bereit: Teil 1: UI/UX-Grundlagen fr Entwickler Teil 2: UI Patterns - Kochrezepte fr die Gestaltung von GUIs Der nchste Chance, einen Vortrag von mir zum Thema UI/UX zu sehen, ist...

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Implementing IDisposable and the Dispose Pattern Properly

The Code Project Latest Articles — Fri, 27 Apr 2012 00:00:00 GMT

This is an alternative for "Implementing IDisposable and the Dispose Pattern Properly"...

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.NET String Resources

The Code Project Latest Articles — Fri, 20 Apr 2012 00:00:00 GMT

Concepts and patterns for the handling of strings in multilingual applications....

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Integration Patterns utilizing the Windows Azure Service Bus

Stephen Kaufman's WebLog — Mon, 16 Apr 2012 00:00:00 GMT

For years we have all utilized Gregor Hohpes Enterprise Integration Patterns book (and the web site). Many of these patterns, if not most, are well known and there are many resources out there that talk about how these patterns can be implemented. There are also a number of resources that talk about how these patterns can be implemented in BizTalk or Windows Server AppFabric. However, there is very little that shows how these patterns can be implemented using the Windows Azure...

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Integration Patterns utilizing the Windows Azure Service BusPart II

Stephen Kaufman's WebLog — Mon, 16 Apr 2012 00:00:00 GMT

In the previous post I covered the Messaging Channel group of patterns. In this post, I will cover the Message Routing Group patterns. This group contains: Content Based Router, Message Filter, Recipient List, Splitter, Aggregator, Resequencer, Composed Message Processor, Scatter-Gather, Process Manager and Message Broker. So, lets dive right in to each of these patterns and see how these can be implemented. Content-Based Router This pattern requires the the router system...

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ZenGallery: a minimalist image gallery for Orchard

More Whidbey stuff — Sat, 31 Mar 2012 00:00:00 GMT

There are quite a few image gallery modules for Orchard but they were not invented here I wanted something a lot less sophisticated that would be as barebones and minimalist as possible out of the box, to make customization extremely easy. So I made this, in less than two days (during which I got distracted a lot). Nwazet.ZenGallery uses existing Orchard features as much as it can: Galleries are just a content part that can be added to any type The set of photos in a gallery is simply defined...

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What is part video game, part science visualization, part art installation and part social experiment?

MSDN: Coding4Fun — Fri, 30 Mar 2012 00:00:00 GMT

Today's inspiration project is another example of how the Kinect is being used to provide experiences and interactions unlike anything we've seen before (outside of the movies at least)...danceroom Spectroscopy (dS) is part video game, part science visualization, part art installation, and part social experiment.Fusing 3d imaging and rigorous quantum mechanics, dS transforms people into energy fields and lets them wander through the nano-quantum world, where they trigger sounds and images.Theres...

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SOA Patterns status update

Cirrus Minor — Fri, 16 Mar 2012 00:00:00 GMT

I want to say I am delighted but I guess relieved is the right word here - I’ve finallysubmittedall the book chapters to manning and I’m now doing an editing round on all the chapters (re-adding missing images, update pattern references, fixing typos etc.). The current (andhopefullyfinal) table of contents is [...]...

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DotNetNuke Patterns and Practices - 2: Testable Controllers

Joe Brinkman — Thu, 01 Mar 2012 00:00:00 GMT

So here it is the first real post in our series on DotNetNuke Patterns and Practices. How do we make our Controllers testable. Historically, DotNetNuke has used a Repository style for manipulating entities in the business layer (rather than an Active Record style) a lightweight Entity class usually suffixed with Info, and a Repository class which has traditionally used Controller as a suffix. This naming strategy was present initially in the iBuySpy Portal Starter-Kit upon which DotNetNuke...

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User Group Tour 2012 zum Thema User Interfaces

Roland Weigelt — Wed, 22 Feb 2012 00:00:00 GMT

Meine kleine User Group Tour im letzten Sommer unter dem Motto UI/UX fr Entwickler und andere Nicht-Designer hat mir viel Spa gemacht so viel Spa, dass auch auch dieses Jahr wieder unterwegs sein werde. Die Planung dazu ist noch im Gange, die folgenden Termine stehen fr meinen neuen Vortrag UI Patterns - Kochrezepte fr die Gestaltung von GUIs bereits fest: 28.02.2012 Bonn (Infos, Anfahrt) 28.03.2012 Koblenz (Infos demnchst online, Anfahrt) 02.07.2012 Dresden (Infos...

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Coding in Marble (Part 2)

Rico Marianis Performance Tidbits — Mon, 20 Feb 2012 00:00:00 GMT

I thought I'd follow up on my last technical post with a few extra details about the Marble pattern, despite the name of the article I mostly talked about the Wood pattern. I guess perhaps this is timely because the use of Promises to represent asynchronous operations is increasingly popular, but these notions are not really limited to context pattern, though promises do make for good examples. So, what are the essential properties? Wood: objects tend to be smaller and more abundant...

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Hazards of Converting Binary Data To A String

youve been HAACKED — Mon, 30 Jan 2012 00:00:00 GMT

Back in November, someone asked a question on StackOverflow about converting arbitrary binary data (in the form of a byte array) to a string. I know this because I make it a habit to read randomly selected questions in StackOverflow written in November 2011. Questions about text encodings in particular really turn me on. In this case, the person posing the question was encrypting data into a byte array and converting that data into a string. The conversion code he used was similar to the following:...

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Getting Older

youve been HAACKED — Mon, 23 Jan 2012 00:00:00 GMT

Birthdays are a funny thing, arent they? Lets look at this tweet for example, It's @haacked's birthday. Give him crap about getting old. No gifts, please. Especially not what Charlie suggests. Of course Im getting older. Were all getting older. Every second of every day and twice on Monday. Every femtosecond even. Perhaps the only time were not getting older is the moment within a Planck time interval. But once that interval is up, yep, youre older. Yet people apparently live their lives...

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How to Build Flexible and Reusable WCF Services

The Code Project Latest Articles — Fri, 20 Jan 2012 00:00:00 GMT

Design patterns and best practices for building flexible and reusable WCF services....

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