What Is New in ASP.NET Core 1.0
| Category | Key Changes |
|---|---|
| Foundation | Complete rewrite as a modular, cross-platform framework built on .NET Core. |
| Tooling | New command-line interface (CLI) tools for project and dependency management. |
| Performance | High-performance, lightweight HTTP request pipeline and modular components. |
| Unification | Merges MVC and Web API frameworks into a single, consistent programming model. |
| Deployment | Flexible deployment options including framework-dependent and self-contained. |
Why is ASP.NET Core 1.0 a complete rewrite?
ASP.NET Core 1.0 is a ground-up rebuild to create a lean, composable framework for the modern web. It was designed from the start to be cross-platform, running on Windows, macOS, and Linux. This architectural shift allows developers to build and deploy applications without being locked into a single operating system.
The new modular HTTP request pipeline means you include only the components your application needs, like middleware for routing or authentication. This results in higher performance and a smaller application footprint compared to the traditional System.Web-based ASP.NET.
How does the new command-line tooling work?
The new .NET Core CLI is the foundation for creating, building, and running applications. You start by using dotnet new to generate a project structure. Managing dependencies is done by editing the project.json file and using dotnet restore to pull in NuGet packages.
In practice, this tooling provides a consistent development experience across all supported platforms. You can build, run, and publish your app from the terminal, which is crucial for Linux and macOS development and CI/CD automation.
What changed with MVC and Web API?
MVC and Web API have been unified into a single framework. Controllers now inherit from Controller and can return both views for HTML and formatted data (JSON, XML) for APIs. This eliminates the artificial separation present in previous versions.
This matters because it simplifies the codebase. You no longer need different controller base classes or routing rules for web pages versus web services. A single controller can handle multiple response formats seamlessly.
What are the new deployment models?
You get two main deployment choices. Framework-dependent deployment relies on a shared .NET Core runtime installed on the target machine. Self-contained deployment bundles your app with its own copy of the .NET Core runtime, making it completely portable.
The self-contained option is powerful for ensuring consistency in production, as you control the exact runtime version. The trade-off is a larger deployment package because it includes the entire framework.
FAQ
Is ASP.NET Core 1.0 the same as ASP.NET 4.6?
No, it is a completely new, cross-platform framework that runs on .NET Core. ASP.NET 4.6 is the traditional Windows-only framework that runs on the full .NET Framework. They are separate products with different base libraries and runtime characteristics.
Can I run my existing ASP.NET MVC 5 application on .NET Core 1.0?
Not directly. The frameworks are significantly different. Porting an existing application requires updating namespaces, reworking the startup logic, and potentially replacing dependencies that are not yet available for .NET Core.
What replaces Web.config and Global.asax?
Application configuration is now typically handled through a JSON-based file (appsettings.json) and environment variables. The startup code, including middleware configuration, is defined in the Startup.cs class, replacing the global application events in Global.asax.
Is Session State available in ASP.NET Core 1.0?
Yes, but it's not enabled by default like in traditional ASP.NET. You must explicitly add and configure the session state middleware as a service in your Startup.cs file, making it an opt-in feature for better performance by default.
How do I manage dependencies without packages.config?
The project.json file is used to manage all project dependencies, tools, and target frameworks. Running dotnet restore reads this file and downloads the specified packages, replacing the function of packages.config and the Visual Studio Package Manager UI for these project types.