The Framework Features Anti-Pattern

examples in ASP.NET / Core

@seangwright

Hello!

About me:

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Tweet at / follow me here

Who am I? I’m Sean G. Wright.

What do I do? I make marketing, business tools and ecommerce stuff with ASP.NET and Angular, consulting and devops/hosting duties.

Where do I work? I’m a dev lead at WiredViews, a web development/marketing agency in Akron.

What’s new in my life? I just installed a new storm-door in the front of my house. It has a retractable screen. It’s like being outside.

How to find me? https://github.com/sgwatgit and https://medium.com/@seangwright

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@seangwright

Please interrupt me :)

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Comments, questions and digressions are welcomed!

@seangwright

What is a Pattern?

@seangwright

Pattern: some definitions

• general, reusable solution to a commonly occurring problem within a given context��formalized best practices �https://en.wikipedia.org/wiki/Software_design_pattern�

• a way to chunk up advice about a topic �should name a solution�should have recurrence�https://www.martinfowler.com/articles/writingPatterns.html

@seangwright

What is an Anti-Pattern?

@seangwright

Anti-Pattern: some definitions

• There must be two key elements to distinguish an anti-pattern from a bad habit:��A commonly used process, structure, or pattern of action that, despite initially appearing to be an appropriate and effective response to a problem, has more bad consequences than good ones��Another solution exists that is documented, repeatable, and proven to be effective�https://en.wikipedia.org/wiki/Anti-pattern

• sensible people will take the path - only once you've put a lot of effort into it will you know it's a bad result��the same solution can be a good pattern in some contexts and an antipattern in others�https://www.martinfowler.com/bliki/AntiPattern.html

@seangwright

You’re a sensible person, but you probably thought this was a good idea at one point

@seangwright

What is a framework?

@seangwright

Framework: some definitions

• software providing generic functionality can be selectively changed by additional user-written code��inversion of control, extensible, not modifiable (O, D in SOLID)�https://en.wikipedia.org/wiki/Software_framework�

• application registers with the framework (note these are separate)��framework calls into the application��A framework often exists to address a particular �general-purpose Domain �(such as web applications, mobile apps, workflows, etc.)�http://blog.ploeh.dk/2014/05/19/di-friendly-framework/

@seangwright

A framework calls you! Your application is features and business logic, not the framework.

@seangwright

What is a Feature?

@seangwright

Feature: some definitions

• small pieces of client-valued functions�https://en.wikipedia.org/wiki/Feature-driven_development�

• "A distinguishing characteristic of a software item (e.g., performance, portability, or functionality)."�https://en.wikipedia.org/wiki/Software_feature

• description of an interaction of a user with the product or some other action that the product can perform�https://martinfowler.com/articles/lean-inception/discover-features.html

@seangwright

Comments or questions?

@seangwright

Framework:��ASP.NET MVC 5

Features:

• Models, Views, Controllers

• Conventions over configuration

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• Razor templating engine

• Service Locator

• Model binding

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• Routing patterns

• Models,Views,Controllers

@seangwright

Focusing on the Framework’s features was an Anti-Pattern

@seangwright

Some project layout examples

@seangwright

MVC was the feature when it came out: https://www.codeguru.com/csharp/article.php/c18167/Top-7-Features-of-the-ASPNET-MVC-Framework.htm�

@seangwright

Some other examples of building by framework (or architectural) features

Building by Framework features

Building by Architectural features

@seangwright

File -> New Project -> ASP.NET Core -> MVC (with User Accounts)

Did they fix it in ASP.NET Core?

Nope!

… well kinda

@seangwright

New Razor Pages project (ASP.NET Core 2.1+)

File -> �New Project -> �ASP.NET Core ->�Web Application (Razor Pages)

Much better!

Want a Resuable/Composable UI?

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Razor Class Library!

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https://docs.microsoft.com/en-us/aspnet/core/mvc/razor-pages/ui-class?view=aspnetcore-2.1&tabs=visual-studio

@seangwright

Comments or questions?

@seangwright

Why focus on your business’s features?

• Developers are usually tasked with building or working on a business feature (UserAccounts), not a layer or framework feature (Controllers).
• What do your user stories look like?�

• Namespaces begin to represent feature dependencies.
• Company.Web.Features.UserAccount vs Company.Web.Controllers

• Hiding unfinished features via feature toggling is easier to keep consistent when you are already thinking in terms of features.

@seangwright

Why focus on your business’s features?

• When reviewing PRs, source control history it becomes easier to pinpoint unnecessary or incorrect changes.
• Why is Company.Web.Features.ProductCoupons.ProductCouponController changed when this PR is for the UserAccount feature?

• It’s easier for new developers to understand and explore your project.
• Do you want to see all Controllers or all Authorization?

• Even if you have teams working on layers (Frontend and Backend), they can learn how their part of the feature integrates with the other team’s.
• Frontend devs can debug an operation moving through the application for their feature even if they don’t write C Pound.

@seangwright

Why focus on your business’s features?

• It’s easier to tell when a feature is becoming too complex based on the number of files in a feature folder.
• Far more useful than making decisions based on the number of Controllers in your application.

• Architecture tends towards less coupling between layers (per feature) and more cohesion within features.
• Easier to re-architect a feature in isolation or have multiple variations of a feature (A/B, perf testing).
• Separate layers at the project level, not the folder level.

@seangwright

Comments or questions?

@seangwright

Now for some code ...

https://github.com/sgwatgit/talks-framework-features-anti-pattern-demos

@seangwright

Some thoughts

• The ‘Framework Features’ project structure is a little like Hungarian notation for variables and types.

• The .NET framework has saddled us with some anti-pattern conventions we still haven’t escaped (Async suffix on Task returning methods, I prefix on Interface types).��Don’t be a victim of cargo cult programming. Identify anti-patterns through experience.

• Framework architects + Stroustrup's Rule
• For new features, people insist on LOUD explicit syntax.
• For established features, people want terse notation.��https://thefeedbackloop.xyz/stroustrups-rule-and-layering-over-time/

• What causes this kind of anti-pattern?

@seangwright

Some thoughts

• Try bringing an ‘application feature’ first mindset to other areas of your work
• Using a literal ‘Features’ folder is not the key, focusing on your application features is.�
• Client side code or assets (.ts, .js. .css, .png, .woff).�
• Unit Test projects structure App.Web.Tests/Features/UserAccounts/UserAccountTests.cs�
• Class libraries
• When features get too large, move them to their own project.

• When you first start using a framework, your view on it tends to be ‘What can this framework do for me?” The focus here is on the framework features.��After becoming experienced with it your view changes to “What can I do with this framework?” The focus here is on the application features you will build.

@seangwright

Links and references (.NET)

• http://marisks.net/2016/02/16/feature-folders-vs-tech-folders/�
• https://bojanv91.github.io/posts/2016/05/feature-folders-structure-in-asp-net�
• http://timgthomas.com/2013/10/feature-folders-in-asp-net-mvc/�
• http://www.chwe.at/2014/04/introducing-the-asp.net-mvc-feature-folders-project-structure/

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@seangwright

Links and references (.NET)

• http://www.matthewrenze.com/articles/clean-architecture-in-asp-net-mvc-5/�
• http://www.meadow.se/wordpress/grouping-by-feature-in-asp-net-mvc/�
• https://softwareengineering.stackexchange.com/questions/310833/why-does-everyone-put-controllers-in-one-folder-and-views-in-another�
• http://www.codinginstinct.com/2013/03/aspnet-mvc-folder-structure.html�
• https://www.gurustop.net/blog/2012/09/11/aspnetmvc4-application-structure-by-features-move-views-by-area/

@seangwright

Links and references (.NET Core)

• Feature Slices for ASP.NET Core MVC - Steve Smith�https://msdn.microsoft.com/en-us/magazine/mt763233.aspx
• https://ardalis.com/api-feature-folders
• https://scottsauber.com/2016/04/25/feature-folder-structure-in-asp-net-core/
• http://codingsight.com/asp-net-core-mvc-feature-folders/
• http://kurtdowswell.com/software-development/asp-net-core-mvc-feature-folders/
• An Opinionated Approach to ASP.NET Core - Scott Allen�https://www.youtube.com/watch?v=WMdBoeQtxUY
• https://github.com/OdeToCode/AddFeatureFolders

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@seangwright

Links and references (Other)

• Clean Architecture and Design - Robert C Martin�https://youtu.be/Nsjsiz2A9mg?t=6m45s�
• Ruby On Rails project structure (probably the source of our MVC Anti-Pattern)�https://www.tutorialspoint.com/ruby-on-rails/rails-directory-structure.htm�
• Python Flask project structure (tutorial matches the Anti-Pattern)�http://flask.pocoo.org/docs/1.0/tutorial/layout/�
• Angular project structure (feature based)�https://angular.io/guide/styleguide#application-structure-and-ngmodules�

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@seangwright

In Summary

• Beware of Anti-Patterns
• Seem like good ideas
• Context dependent
• Avoided through experience

• Use Frameworks to help you do more
• They are tools
• Use their features
• Do not let the framework use you (like in Soviet Russia)

• Focus on your business’s / application features
• They are what actually make you money
• This helps your team grow, understand and maintain your code

@seangwright

Comments or questions?

… you thought there’d be a funny gif here, didn’t you?

@seangwright

No more slides.

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Thanks!

@seangwright