Scott Hanselman

How to reference an existing .NET Framework Project in an ASP.NET Core 1.0 Web App

October 8, '16 Comments [25] Posted in ASP.NET | ASP.NET MVC
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I had a reader send me a question yesterday. She basically wanted to use her existing .NET Framework libraries in an ASP.NET Core application, and it wasn't super clear how to do it.

I have a quick question for you regarding asp.net core. We are rewriting our website using asp.net core, empty from the bottom up. We have 2 libraries written in .net 4.6 . One is our database model and repositories and the other is a project of internal utilities we use a lot. Unfortunately we cannot see how to reference these two projects in our .net core project.

It can be a little confusing. As I mentioned earlier this week, some people don't realize that ASP.NET Core 1.0 (that's the web framework bit) runs on either .NET Core or .NET Framework 4.6 aka "Full Framework."

ASP.NET Core 1.0 runs on ASP.NET 4.6 nicely

When you make a new web project in Visual Studio you see (today) this dialog. Note in the dropdown at the top you can select your minimum .NET Framework version. You can select 4.6.2, if you like, but I'll do 4.5.2 to be a little more compatible. It's up to you.

File New Project

This dialog could use clearer text and hopefully it will soon.

  • There's the regular ASP.NET Web Application at the top. That's ASP.NET 4.6 with MVC and Web API. It runs on the .NET Framework.
  • There's ASP.NET Core 1.0 running on .NET Core. That's cross platform. If you select that one you'll be able to run your app anywhere but you can't reference "Full" .NET Framework assemblies as they are just for Windows.  If you want to run anywhere you need to use .NET Standard APIs that will run anywhere.
  • There's ASP.NET Core 1.0 running on .NET Framework. That's the new ASP.NET Core 1.0 with unified MVC and Web API but running on the .NET Framework you run today on Windows.

As we see in the diagram above, ASP.NET Core 1.0 is the new streamlined ASP.NET  that can run on top of both .NET Framework (Windows) and .NET Core (Mac/Windows/Linux).

I'll chose ASP.NET Core on .NET Framework and I'll see this in my Solution Explorer:

Web App targeting .NET Framework 4.5.2

I've got another DLL that I made with the regular File | New Project | Class Library.

New Class Library

Then I reference it the usual way with Add Reference and it looks like this in the References node in Solution Explorer. Note the icon differences.

Adding ClassLibrary1 to the References Node in Solution Explorer

If we look in the project.json (Be aware that this will change for the better in the future when project.json's functionality is merged with csproj and msbuild) you'll note that the ClassLIbrary1 isn't listed under the top level dependencies node, but as a framework specific dependency like this:

{
"dependencies": {
"Microsoft.StuffAndThings": "1.0.0",
"Microsoft.AspNetCore.Mvc": "1.0.1",
},

"frameworks": {
"net452": {
"dependencies": {
"ClassLibrary1": {
"target": "project"
}
}
}
}
}

Notice also that in this case it's a type="project" dependency in this case as I didn't build a NuGet package and reference that.

Since the .NET Core tooling is in preview there are some gotchas when doing this today.

  • Make sure that all your class libraries are targeting an appropriate version of the .NET Framework.
    • For example, don't have a 4.5.2 Web App targeting a 4.6.2 Class Library. This could bite you in subtle ways if things don't line up in production.
  • dotnet restore at the command line may well get confused and give you an error like:
    • Errors in D:\github\WebApplication2\src\WebApplication2\project.json - Unable to resolve 'ClassLibrary1' for '.NETFramework,Version=v4.5.2'.
    • Use Visual Studio to build or run msbuild at the command line.
  • You can restore packages from the command line with nuget.exe version 3.4.4 or greater if you restore on the .sln file like this:
    • D:\github\WebApplication2>nuget restore WebApplication2.sln
      MSBuild auto-detection: using msbuild version '14.0' from 'C:\Program Files (x86)\MSBuild\14.0\bin'.
    • I recommend you run nuget.exe to see what version you have and run nuget update -self to have it update itself.

These gotchas will be fixed when the tooling is finalized.

Hope this helps!


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About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Sharing Authorization Cookies between ASP.NET 4.x and ASP.NET Core 1.0

October 2, '16 Comments [15] Posted in ASP.NET | ASP.NET MVC
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ASP.NET Core 1.0 runs on ASP.NET 4.6 nicelyASP.NET Core 1.0 is out, as is .NET Core 1.0 and lots of folks are making great cross-platform web apps. These are Web Apps that are built on .NET Core 1.0 and run on Windows, Mac, or Linux.

However, some people don't realize that ASP.NET Core 1.0 (that's the web framework bit) runs on either .NET Core or .NET Framework 4.6 aka "Full Framework."

Once you realize that it can be somewhat liberating. If you want to check out the new ASP.NET Core 1.0 and use the unified controllers to make web apis or MVC apps with Razor you can...even if you don't need or care about cross-platform support. Maybe your libraries use COM objects or Windows-specific stuff. ASP.NET Core 1.0 works on .NET Framework 4.6 just fine.

Another option that folks don't consider when talk of "porting" their apps comes up at work is - why not have two apps? There's no reason to start a big porting exercise if your app works great now. Consider that you can have a section of your site by on ASP.NET Core 1.0 and another be on ASP.NET 4.x and the two apps could share authentication cookies. The user would never know the difference.

Barry Dorrans from our team looked into this, and here's what he found. He's interested in your feedback, so be sure to file issues on his GitHub Repo with your thoughts, bugs, and comments. This is a work in progress and at some point will be updated into the official documentation.

Sharing Authorization Cookies between ASP.NET 4.x and .NET Core

Barry is building a GitHub repro here with two sample apps and a markdown file to illustrate clearly how to accomplish cookie sharing.

When you want to share logins with an existing ASP.NET 4.x app and an ASP.NET Core 1.0 app, you'll be creating a login cookie that can be read by both applications. It's certainly possible for you, Dear Reader, to "hack something together" with sessions and your own custom cookies, but please let this blog post and Barry's project be a warning. Don't roll your own crypto. You don't want to accidentally open up one or both if your apps to hacking because you tried to extend auth/auth in a naïve way.

First, you'll need to make sure each application has the right NuGet packages to interop with the security tokens you'll be using in your cookies.

Install the interop packages into your applications.

  1. ASP.NET 4.5

    Open the nuget package manager, or the nuget console and add a reference to Microsoft.Owin.Security.Interop.

  2. ASP.NET Core

    Open the nuget package manager, or the nuget console and add a reference to Microsoft.AspNetCore.DataProtection.Extensions.

Make sure the Cookie Names are identical in each application

Barry is using CookieName = ".AspNet.SharedCookie" in the example, but you just need to make sure they match.

services.AddIdentity<ApplicationUser, IdentityRole>(options =>
{
options.Cookies = new Microsoft.AspNetCore.Identity.IdentityCookieOptions
{
ApplicationCookie = new CookieAuthenticationOptions
{
AuthenticationScheme = "Cookie",
LoginPath = new PathString("/Account/Login/"),
AccessDeniedPath = new PathString("/Account/Forbidden/"),
AutomaticAuthenticate = true,
AutomaticChallenge = true,
CookieName = ".AspNet.SharedCookie"

};
})
.AddEntityFrameworkStores<ApplicationDbContext>()
.AddDefaultTokenProviders();
}

Remember the CookieName property must have the same value in each application, and the AuthenticationType (ASP.NET 4.5) and AuthenticationScheme (ASP.NET Core) properties must have the same value in each application.

Be aware of your cookie domains if you use them

Browsers naturally share cookies between the same domain name. For example if both your sites run in subdirectories under https://contoso.com then cookies will automatically be shared.

However if your sites run on subdomains a cookie issued to a subdomain will not automatically be sent by the browser to a different subdomain, for example, https://site1.contoso.com would not share cookies with https://site2.contoso.com.

If your sites run on subdomains you can configure the issued cookies to be shared by setting the CookieDomain property in CookieAuthenticationOptions to be the parent domain.

Try to do everything over HTTPS and be aware that if a Cookie has its Secure flag set it won't flow to an insecure HTTP URL.

Select a common data protection repository location accessible by both applications

From Barry's instructions, his sample will use a shared DP folder, but you have options:

This sample will use a shared directory (C:\keyring). If your applications aren't on the same server, or can't access the same NTFS share you can use other keyring repositories.

.NET Core 1.0 includes key ring repositories for shared directories and the registry.

.NET Core 1.1 will add support for Redis, Azure Blob Storage and Azure Key Vault.

You can develop your own key ring repository by implementing the IXmlRepository interface.

Configure your applications to use the same cookie format

You'll configure each app - ASP.NET 4.5 and ASP.NET Core - to use the AspNetTicketDataFormat for their cookies.

Cookie Sharing with ASP.NET Core and ASP.NET Full Framework

According to his repo, this gets us started with Cookie Sharing for Identity, but there still needs to be clearer guidance on how share the Identity 3.0 database between the two frameworks.

The interop shim does not enabling the sharing of identity databases between applications. ASP.NET 4.5 uses Identity 1.0 or 2.0, ASP.NET Core uses Identity 3.0. If you want to share databases you must update the ASP.NET Identity 2.0 applications to use the ASP.NET Identity 3.0 schemas. If you are upgrading from Identity 1.0 you should migrate to Identity 2.0 first, rather than try to go directly to 3.0.

Sound off in the Issues over on GitHub if you would like to see this sample (or another) expanded to show more Identity DB sharing. It looks to be very promising work.


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About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Lonely Coding

September 30, '16 Comments [33] Posted in Musings
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It's official. I'm a better programmer when I'm pairing with someone. Pair Programming (two people, one keyboard) has been around for at least 20+ years, if not much longer. Usually one person types while another person (paces around and) thinks. It is kind of a "driver and navigator" model.

Everyone is different, to be clear, so it's very possible that you are the kind of person who can disappear into a closet for 8 hours and emerge with code, triumphant. I've done this before. Some of my best projects have involved me coding alone and that's fine.

However, just has we know that "diverse teams make for better projects," the same is true in my experience when coding on specific problems. Diversity isn't just color and gender, etc, it's as much background, age, personal history, work experience, expertise, programming language of choice, heck, it's even google-ability, and more!

How many times have you banged your head against a wall while coding only to have a friend or co-worker find the answer on their first web search?

Good pair programming is like that. Those ah-ha moments happen more often and you'll feel more than twice as productive in a pair.

In fact, I'm trying to pair for an hour every week remotely. Mark Downie and I have been pairing on DasBlog on and off for a year or so now in fits and starts. It's great. Just last week he and I were trying to crack one problem using regular expressions (yes, then we had two problems) and because there were two of us looking at the code it was solved!

Why is pair programming better?

Here's a few reasons why I think Pair Programming is very often better.

  • Focus and Discipline - We set aside specific times and we sprint. We don't chat, we don't delete email, we code. And we also code with a specific goal or endpoint in mind.
  • Collective ownership - I feel like we own the code together. I feel less ego about the code. Our hacks are our hacks, and our successes are shared.
  • Personal growth - We mentor each other. We learn and we watch how the other moves around the code. I've learned new techniques, new hotkeys, and new algorithms.

Let's talk about the remote aspect of things. I'm remote. I also like to poke around on non-work-related tech on the side, as do many of us. Can I pair program remotely as well? Absolutely. I start with Skype, but I also use Google Hangouts, Join.me, TeamViewer, whatever works that day.

If you're a remote person on a larger team, consider remote pair programming. If you're an consultant  or perhaps you've left a big corporate job to strike off on your own, you might be lonely. Seriously, ask yourself that hard question. It's no fun to realize or have to declare you're a lonely coder, but I am and I will. I love my job and I love my team but if I go a day or two without seeing another human or spending some serious time on Skype I get really tense. Remote pair programming can really reduce that feeling of lonely coding.

I was at a small tech get together in Atlanta a few days ago and I knew that one person there was a singular coder at their small business while another at the table was an emerging college student with an emerging talent. I made a gentle suggestion that maybe they consider pairing up on some side projects and they both lit up.

Consider your networks. Are there people you've met at conferences or at local user groups or meetups that might be good remote pairing partners? This might be the missing link for you. It was for me!

Do you pair? Do you pair remotely? Let us all know in the comments.

* Stock photo purchased from ColorStock - Your customers are diverse, why aren't your stock photos?


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About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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FIXED: Xbox One losing TV signal error message with DirectTV

September 28, '16 Comments [16] Posted in Gaming
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Your TV signal was lostI've got an Xbox One that I love that is connected to a DirectTV HDTV Receiver that I love somewhat less. The setup is quite simple. Since I can control the DirectTV with the Xbox One and we like to switch between Netflix and Hulu and DirectTV we use the Xbox One to control everything.

The basic idea is this, which is quite typical with an Xbox One. In theory, it's amazing.

I fixed my Xbox One losing Signal with an HDMI powered splitter

However, this doesn't always work. Often you'll turn on the whole system and the Xbox will say "Your TV Signal was lost. Make sure your cable or satellite box is on and plugged into the Xbox." This got so bad in our house that my non-technical spouse was ready to "buy a whole new TV." I was personally blaming the Xbox.

It turns out that's an issue of HDMI compliance. The DirectTV and other older cable boxes aren't super awesome about doing things the exact way HDMI like it, and the Xbox is rather picky about HDMI being totally legit. So how do I "clean" or "fix" my HDMI signal from my Cable/Satellite receiver?

I took at chance and asked on Reddit and this very helpful user (thanks!) suggested an HDMI splitter. I was surprised but I was ready to try anything so I ordered this 2 port HDMI powered splitter from Amazon for just US$20.

ADDING AN HDMI SPLITTED WORKS - TOTALLY SOLVED THE PROBLEM

It totally works. The Xbox One now does its "negotiations" with the compliant splitter, not with the Receiver directly and we haven't seen a single problem since.

I fixed my Xbox One losing Signal with an HDMI powered splitter

If you have had this problem with your Xbox One then pick up a 2 port HDMI powered splitter and rejoice. This is a high quality splitter than doesn't change the audio signal and still works with HDCP if needed. Thanks internets!


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About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Self-contained .NET Core Applications

September 18, '16 Comments [29] Posted in DotNetCore | Open Source
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Just in case you missed it, .NET is all open source now and .NET Core is a free, open source, cross-platform framework that you can download and start with in <10 minutes. You can get it on Mac, Windows, and a half-dozen Unixes at http://dot.net. Take that along with the free, cross-platform Visual Studio Code and you'll be writing C# and F# all over the place.

Ok, that said, there's two ways to deploy a .NET Core application. There's FDD and SCD. Since TLAs (three letter acronyms) are stupid, that's Framework-dependent and Self-contained. When .NET Core is installed it ends up in C:\program files\dotnet on Windows, for example. In the "Shared" folder there's a bunch of .NET stuff that is, well, shared. There may be multiple folders, as you can see in my folder below. You can have many and multiple installs of .NET Core.

When you're installing your app and its dependencies BUT NOT .NET Core itself, you're dependent on .NET Core already being on the target machine. That's fine for Web Apps or systems with lots of apps, but what if I want to write an app and give it to you as zip or on a USB key and and I just want it to work. I'll include .NET Core as well so the whole thing is a Self Contained Deployment.

It will make my "Hello World" application larger than if I was using an existing system-wide install, but I know it'll Just Work because it'll be totally self-contained.

Where is .NET Core installed to?

If I deploy my app along with .NET Core it's important to remember that I'll be responsible for servicing .NET Core and keeping it up to date. I also need to decide on my target platforms ahead of time. If I want it to run on Windows, Mac, and Linux AND just work, I'll need to include those target platforms and build deployment packages for them. This all makes mostly intuitive sense but it's good to know.

I'll take my little app (I'm just using a "dotnet new" app) and I'll modify project.json in a text editor.

My app is a .NETCore.App, but it's not going to use the .NET Core platform that's installed. It'll use a local version so I'll remove "type="platform"" from this dependency.

"frameworks": {
"netcoreapp1.0": {
"dependencies": {
"Microsoft.NETCore.App": {
"version": "1.0.1"
}
}
}
}

Next I'll make a runtimes section to specify which ones I want to target. There's a list of ALL the Runtime IDs here.

"runtimes": {
"win10-x64": {},
"osx.10.10-x64": {},
"ubuntu.14.04-x64": {}
}

After running "dotnet restore" you'll want to build for each of these like this:

dotnet build -r win10-x64
dotnet build -r osx.10.10-x64
dotnet build -r ubuntu.14.04-x64

And then publish release versions after you've tested, etc.

dotnet publish -c release -r win10-x64
dotnet publish -c release -r osx.10.10-x64
dotnet publish -c release -r ubuntu.14.04-x64

Once this is done, I've got my app self-contained in n folders, ready to deploy to whatever systems I want.

Self-contained .NET app built for 3 OSs

You can see in the Win10 folder there's my "MYAPPLICATION.exe" (mine is called scd.exe) that can be run, rather than running things like developers do with "dotnet run."

I run foo.exe, not dotnet.exe now

There's lots of good documentation about how you can tune and define exactly what gets deployed with your self contained application over at the .NET Core Docs. You can do considerable trimming to .NET Core, and there's talk of that becoming more and more automated in the future, possibly down to the method level.


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About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Disclaimer: The opinions expressed herein are my own personal opinions and do not represent my employer's view in any way.