Intro to SignalR in C# Part 1 - using Blazor, WPF, best practices, and more 

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Good to know.

Thanks for the suggestion. Please add it to the list on the suggestion site so others can vote on it as well: suggestions.iamtimcorey.com/

+1 Upvoted on Tim's suggestion site

I agree. I tried this awhile ago using Azure B2C and ended up having to make the hub anonymous because I couldn't figure out how to get the token to signalR hub

@@IAmTimCorey I went there and registered and upvoted this suggestion. What do the Statuses mean? They're for the most part self explanatory, but what does "Watching' actually mean? I thought for a second you somehow knew what videos I was watching and had completed.

Thanks for sharing. I'm curious as to what circumstances led you to this conclusion. I agree that calling a controller is the better option, but in general, you can also use the SignalR connection without issue. For instance, that's what Blazor Server does for all of its data storage calls. Having a call timeout is something that shouldn't happen with an actively-used client. Plus with the auto-reconnect, it should jump right back up when you try to use it in a disconnected state.

@@IAmTimCorey there were several reasons I wanted to do this. 1. It made all of our application structure consistent (all POST data goes through controllers). 2. It fit our development process, we had a guy that worked on hubs and another guy that works with data storage, for example. 3. We had connection issues (although this was minor). 4. Authentication. Sending the posted data through our controllers meant we used our normal request authentication. Which is via JWT tokens passed in an HTTP header. 5. It allowed us to broadcast system generated data. For example, our chat had system messages, and using the HubContext, system chat messages were broadcasted the same way user chat messages were broadcasted.

@@IAmTimCorey I just highly suggest implementing it this way to save yourself in the future. It's just a lot cleaner and more flexible.

Thanks for sharing.

Great to hear!

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You are welcome.

Short answer to this is no. You should use WebRTC for streaming video. There are frontend libraries for making this simpler to setup (although it's still not trivial). Remember, SignalR uses WebSockets, which means your server plays a middle-man role. Whereas, WebRTC connects two clients directly and streams data between the two (you can use SignalR to orchestrate the connection between the two clients but you won't use SignalR for streaming video/audio between the clients). I created a live meeting feature in one of my apps using WebRTC and it works really well. It's works identical to Zoom or Skype.

Thanks for sharing @Andy!

I am glad it was helpful.

Thanks for the suggestion. Please add it to the list on the suggestion site so others can vote on it as well: suggestions.iamtimcorey.com/

Need this too for a project currently in development

Yes, you can add authentication and authorization to a SignalR hub.

"Any asynchronous operations, which require the component to re-render once they complete, should be placed in the OnInitializedAsync method." - from the documentation. Since the results of the call may put something on the page, which would cause the the component to re-render, we use the OnInitializedAsync method.

That sounds like this suggestion: suggestions.iamtimcorey.com/Details/61d8c74f0761534f2283c321

Thank you!

You are welcome. I am glad it was helpful.

Yes it is. The next video will send ints, but you can send more complex types too.

I send objects through in a little app I'm playing with so yes it's possible.

Thanks!

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You are welcome.

You are welcome.

You are welcome.

Thank you!

Thanks for the suggestion. Please add it to the list on the suggestion site so others can vote on it as well: suggestions.iamtimcorey.com/

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You are welcome.

You are welcome.

Nope.

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You are welcome.

I had double-subscribed to the event, which is why it came through twice.

There should be very few, if any, changes between Blazor Server and MVC. The underlying structure of both is ASP.NET Core.

That could be the right solution if you need that communication channel open for real-time events. Just note that your clients will need to be connected to the API all the time. That probably isn't a problem, but I just wanted to mention it.

@@IAmTimCorey thank you! I appreciate the response!

I don't. I just don't like using them incorrectly.

Interesting. Thanks for sharing.

Directly? No, you can't do that. You need to go through a web server. The web server could host the SignalR server. The problem is that SignalR requires a constant connection. Just keep that in mind. It might be easier to send a message and process it right away on the other end.

I hope you enjoyed it.

Great!

I used WPF as an example app, but yes, I would probably use WPF instead of the Windows SDK App (what a horrible name, by the way). The reason why is because I can run my WPF app on a variety of Windows platforms. The Windows SDK App is restricted to Windows 10 build 1809 or higher or Windows 11. That's it. It also is more complex to set up. Microsoft keeps trying to make UWP-style apps, but that's not going to work. .NET MAUI will introduce cross-platform desktop apps shortly. That's a better option. The Uno Platform uses WPF to make fully cross-platform apps (Windows, Mac, Linux, iOS, Android, and the web). That's a much better option. At the end of the day, though, WPF is a simple yet modern platform for examples.

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Azure has a SignalR service you can use.

That is literally the first couple of sentences in the video. I explain what SignalR is and how it works. Here is the opening paragraph of information: "SignalR is an excellent way to connect two or more clients together for real-time communication. The best part is that this library is just a wrapper around web-standard technologies such as Web Sockets and Long-Polling. It just makes them easier to use. That means we can even use SignalR with other clients such as Java or JavaScript. In this video, we are going to learn how to set up SignalR and how to connect to it using web clients and desktop clients. Throughout the video, we will cover best practices, as well as how to use this in the real world."

Either they need to be able to directly talk to each other or you need to have a web server act as the middle piece.

Yes, when a connection is open, the server can talk to the client or the client can talk to the server.

Yes, you need to install the Desktop project types if you want to use them (WPF is included in that set). You also need to be on Windows, since WPF relies on Windows dlls.

Taking on SignalR isn't something a junior engineer should be doing. There are a lot of prerequisites.

I would recommend the C# Mastercourse ( www.iamtimcorey.com/p/c-mastercourse ). I know you don't need to start from scratch, but it will cover topics that you might otherwise miss at the earlier spots. It will cover a large swath of C#, plus when you purchase the course, you get three bonus courses. One, the Year of Coding, coaches you through the main course and adds additional practice (and solutions), quarterly evaluations of your progress, and expert advice. Another, the .NET Versions course, walks you through the changes to .NET over the past 20 years and what the implications of those changes are. The third, .NET Legacy, gives you the legacy .NET Framework training that has been replaced with .NET 6 training. That way, if you are working on a .NET Framework project, you still have access to the content that covers it.

No, because you can have a closed connection. That isn't the same thing as a null hubConnection.

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Thanks for the suggestion. Please add it to the list on the suggestion site so others can vote on it as well: suggestions.iamtimcorey.com/

I missed that.

Yes, you can host a SignalR service without it being a web app. Azure even provides something like that.

@@IAmTimCorey thanks ;) I succeed using topshelf, I created a windows service (thanks to another video from this channel)

SignalR is just a wrapper around Web Sockets to make them easier. Also, if a client does not support Web Sockets, SignalR will step down to another technology (server events) and then the final (long polling) instead of refusing the connection.

You could do either, but it is probably better to have one signal that transmits all of your data rather than two connections per client.

Ok Tim, I will try it, thank you.

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I would recommend not doing that. Use an API to send an image. You can send a message to get an image from the API through SignalR, though.

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Yes, you would just need to adjust to having a Startup.cs

You can do that.

@@IAmTimCorey hope next part we seen that in action

It is possible to do that, if that is what you are asking. In this demo, though, I wanted to demonstrate each of the actions so they were visible and obvious.

@@IAmTimCorey I mean, you've subscribed to all the connection state changes within constructor where you create connection. But message handler is added only within openConnection_click handler (arount 58:35) where you starting connection. That made me think that this message subscriptions kind of volatile and should be done every time we starting connection. But later on (around 1:09:42) you've connected second time and got message doubled, so I assume this subscription should be done only once within constructor together with connection state change subscriptions. Anyway, I think I've got what I needed while writing this. Thank you for you efforts to make good content publicly awailable on RU-vid!

Thanks for the suggestion. Please add it to the list on the suggestion site so others can vote on it as well: suggestions.iamtimcorey.com/

The SignalR server is going to be C#. However, the client can be just about anything (JavaScript, C#, Java, etc.)

@@IAmTimCorey Yes sir you are right, I was simply saying it would have been nice to have an approach which is mostly used in industry, the one you have given is also classic and quite amazing. If possible have a small tutorial for Signal R with react or Angular 🙂

Thank you!

I am glad it was so helpful.

Thanks for the suggestion. Please add it to the list on the suggestion site so others can vote on it as well: suggestions.iamtimcorey.com/

Streaming video isn't really something that should be done via SignalR. There are other technologies out there that will do a better job.

SignalR isn't really for streaming video. It could stream information around the video (when the play button was clicked, etc.), though.

I forgot to unsubscribe from the SendMessage event when the server disconnected. When it reconnected, I subscribed for a second time. Thus, the two messages (one from each subscription to the event).

You are welcome.

You can use this with any application type, not just web applications. It does need to communicate over the web (or at least to a web server, which can be internal to a network).

I thought the same, but the VS just couldn't find 'Hub' class. Am i missing something ? *edit: The solution for that is editing csproj file and change project sdk to "Microsoft.NET.Sdk.Web"

My pleasure!

SignalR is for maintaining a constant connection to a server. It is primarily for real-time data communication. While it can be used like an API as well, it isn't the ideal use case. An API is useful for when you need information or want to give information. You only open the connection long enough to perform the action and then you close it down again.

Absolutely. It is the best desktop app choice Microsoft has. It deploys to the most Windows platforms and, if you use Uno, you can deploy it to Mac, Linux, iOS, Android, and the web.

It would not be advisable. WebRTC is the better option.

Thanks,@@IAmTimCorey. it is a cross platform solution with core 6 API, UWP and MAUI at presentation layer. still adviceable ?

Great!

Blazor is probably the simplest of the server-side languages. My recommendation would be to give it a shot. I have an intro to Blazor Server that might help.

@@IAmTimCorey can I use Blazor and JS in the same time at one project?

Yes you can.

If the structure of your architecture is such that you cannot use SignalR, you need to rethink your structure. Your structure should work for you, not work against you.

I'll add that to my suggestion list. It is possible.

VSCode is a great editor. If you can use Visual Studio, you will have more help (Intellicode, quick actions and refactoring, etc.), but VSCode is light, fast, and does not get in the way.

We can. I mentioned that in the video. We just don’t need to do it until the load justifies it.

You are welcome.

Thanks!

That sounds like this suggestion: suggestions.iamtimcorey.com/Details/6253bf2a0b6906f2d6876be7

Glad you enjoyed it!

Thanks!

Great to hear!

You are welcome. And yep, just a slip of the tongue.