Scott Hanselman

What is Blazor and what is Razor Components?

March 19, '19 Comments [12] Posted in ASP.NET | Javascript | Open Source
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I've blogged a little about Blazor, showing examples like Compiling C# to WASM with Mono and Blazor then Debugging .NET Source with Remote Debugging in Chrome DevTools as well as very early on asking questions like .NET and WebAssembly - Is this the future of the front-end?

Let's back up and level-set.

What is Blazor?

Blazor is a single-page app framework for building interactive client-side Web apps with .NET. Blazor uses open web standards without plugins or code transpilation. Blazor works in all modern web browsers, including mobile browsers.

You write C# in case of JavaScript, and you can use most of the .NET ecosystem of open source libraries. For the most part, if it's .NET Standard, it'll run in the browser. (Of course if you called a Windows API or a Linux specific API and it didn't exist in the client-side browser S world, it's not gonna work, but you get the idea).

The .NET code runs inside the context of WebAssembly. You're running "a .NET" inside your browser on the client-side with no plugins, no Silverlight, Java, Flash, just open web standards.

WebAssembly is a compact bytecode format optimized for fast download and maximum execution speed.

Here's a great diagram from the Blazor docs.

Blazor runs inside your browser, no plugins needed

Here's where it could get a little confusing. Blazor is the client-side hosting model for Razor Components. I can write Razor Components. I can host them on the server or host them on the client with Blazor.

You may have written Razor in the past in .cshtml files, or more recently in .razor files. You can create and share components using Razor - which is a mix of standard C# and standard HTML, and you can host these Razor Components on either the client or the server.

In this diagram from the docs you can see that the Razor Components are running on the Server and SignalR (over Web Sockets, etc) is remoting them and updating the DOM on the client. This doesn't require Web Assembly on the client, the .NET code runs in the .NET Core CLR (Common Language Runtime) and has full compatibility - you can do anything you'd like as you are not longer limited by the browser's sandbox.

Here's Razor Components running on the server

Per the docs:

Razor Components decouples component rendering logic from how UI updates are applied. ASP.NET Core Razor Components in .NET Core 3.0 adds support for hosting Razor Components on the server in an ASP.NET Core app. UI updates are handled over a SignalR connection.

Here's the canonical "click a button update some HTML" example.

@page "/counter"

<h1>Counter</h1>

<p>Current count: @currentCount</p>

<button class="btn btn-primary" onclick="@IncrementCount">Click me</button>

@functions {
int currentCount = 0;

void IncrementCount()
{
currentCount++;
}
}

You can see this running entirely in the browser, with the C# .NET code running on the client side. .NET DLLs (assemblies) are downloaded and executed by the CLR that's been compiled into WASM and running entirely in the context of the browser.

Note also that I'm stopped at a BREAKPOINT in C# code, except the code is running in the browser and mapped back into JS/WASM world.

Debugging Razor Components on the Client Side

But if I host my app on the server as hosted Razor Components, the C# code runs entirely on the Server-side and the client-side DOM is updated over a SignalR link. Here I've clicked the button on the client side and hit the breakpoint on the server-side in Visual Studio. No there's no POST and no POST-back. This isn't WebForms - It's Razor Components. It's a SPA app written in C#, not JavaScript, and I can change the locations of the running logic, while the UI remains always standard HTML and CSS.

Debugging Razor Components on the Server Side

It's a pretty exciting time on the open web. There's a lot of great work happening in this space and I'm very interesting to see how frameworks like Razor Components/Blazor and Phoenix LiveView change (or don't) how we write apps for the web.


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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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Xbox Avatar accessories for People with Diabetes! Sponsored by Nightscout and Konsole Kingz

March 14, '19 Comments [1] Posted in Diabetes | Gaming
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My Xbox user name is Glucose for a reason.

This is a passion project of mine. You've likely seen me blog about diabetes for many many years. You may have enjoyed my diabetes hacks like lighting up my keyboard keys to show me my blood sugar, or some of the early work Ben West and I did to bridge Dexcom's cloud with the NightScout open source diabetes management system.

Recently Xbox announced new avatars! They look amazing and the launch was great. They now have avatars in wheelchairs, ones with artificial limbs, and a wide variety of hair and skin tones. This is fantastic as it allows kids (and adults!) to be seen and be represented in their medium of choice, video games.

I was stoked and immediately searched the store for "diabetes." No results. No pumps, sensors, emotes, needles, nothing. So I decided to fix it.

NOW AVAILABLE: Go and buy the Nightscout Diabetes CGM avatar on the Xbox Store now!

I called two friends - my friends at the Nightscout Foundation, dedicated to open source and open data for people with diabetes, as well as my friends at Konsole Kingz, digital avatar creators extraordinaire with over 200 items in the Xbox store from kicks to jerseys and tattoos.

And we did it! We've added our first diabetes avatar top with some clever coding from Konsole Kingz, it is categorized as a top but gives your avatar not only a Nightscout T-Shirt with your choice of colors, but also a CGM (Continuous Glucose Meter) on your arm!

Miss USA has a CGMFor most diabetics, CGMs are the hardware implants we put in weekly to tell us our blood sugar with minimal finger sticks. They are the most outwardly obvious physical manifestation of our diabetes and we're constantly asked about them. In 2017, Miss USA contestant Krista Ferguson made news by showing her CGM rather than hiding it. This kind of visible representation matters to kids with diabetes - it tells them (and us) that we're OK.

You can find the Nightscout CGM accessory in a nuimber of ways. You can get it online at the Xbox Avatar shop, and when you've bought it, it'll be in the Purchased Tab of the Xbox Avatar Editor, under Closet | Tops.

You can even edit your Xbox Avatar on Windows 10 without an Xbox! Go pick up the Xbox Avatar Editor and install it (on both your PC and Xbox if you like) and you can experiment with shirt and logo color as well.

Consider this a beta release. We are working on improving resolution and quality, but what we really what to know is this - Do you want more Diabetes Xbox Avatar accessories? Insulin pumps on your belt? An emote to check your blood sugar with a finger stick?

Diabetes CGM on an Xbox avatar

If this idea is a good one and is as special to you and your family (and the gamers in your life with diabetes) please SHARE it. Share it on social media, tell your friends at the news. Profits from this avatar item will go to the Nightscout Foundation!


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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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How to stream PC games from Windows 10 to your Xbox One for free

March 12, '19 Comments [6] Posted in Gaming
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Xbox is ready for you to connect to wirelesslyI've been really enjoying my Xbox lately (when the family is asleep) as well as some fun Retrogaming on original consoles. Back in 2015 I showed how you can stream from your Xbox to any PC using the Xbox app from the Windows Store. You can pair your Xbox controller with any PC you've got around (either with the $20 Xbox Wireless Adapter or just with a micro-USB cable you likely have already). In fact, I often walk on the treadmill while streaming games from the Xbox to my little Surface Pro 3.

Then, a year later I did the inverse. I played PC games on my big screen using a SteamLink! Although they've been discontinued, they are out there and they work great. This little box lets you play PC games remotely on your large screens. I have a big PC in my office and I wanted to use the big TV in the living room. The game still runs on the PC but the video/audio and controls are all remoted to the Xbox. Plus, SteamLink only works with the Steam app running and is optimized for Steam games. It's a single task box and one more thing to plug into HDMI but it works well.

Fast-forward to today and I learned that Windows 10 can project its screen to an Xbox One AND you can use your Xbox One controller to control it (it's paired on the Xbox side) and play games or run apps. No extra equipment needed.

I installed the Xbox Wireless Display App on my Xbox One. Then on my PC, here's what I see upon pressing Win+P and clicking "Connect to Wireless Display."

Connected to Xbox One

Once I've duplicated, you can see here I'm writing this blog post wirelessly projected to the Xbox. It just worked. Took 5 min to do this.

If you're tech savvy, you may say, isn't this "just Miracast" and "hasn't this always been possible?" Yes and no. What's been updated is the Xbox Wireless Display App that you'll want to install and run on your Xbox. You may have been able to project your PC screen to various sticks and Miracast adapters, but this free app makes your Xbox a receiver for Miracast broadcasts (over wifi or LAN) and most importantly - now you can use your Xbox controller already paired to the Xbox to control the remote PC. You can use that control to play games or switch to mouse control mode with Start+Select and mouse around with your Xbox thumbsticks!

20190315_050720572_iOS

If I hit the menu button I can see how the controllers map to PC controls. No remote keyboard and mouse connected from the Xbox...yet. (and to be clear, no word if that will ever be supported but it'd be cool!)

Controller Mapping for PC to Xbox

To make sure you can do this, run DxDiag and save all information into "DxDiag.txt." Here's part of mine. There's nothing special about my machine. It's worth pointing out I have no Wifi adapter on this machine and it has an NVidia 1080 video card. Miracast is happening over the Wired LAN (local area network) in my house. This is Miracast over Infrastructure and it's in Windows 10 since version 1703 (March 2017).

------------------
System Information
------------------
Machine name: IRONHEART
Operating System: Windows 10 Pro 64-bit
Processor: Intel(R) Core(TM) i9-7900X CPU @ 3.30GHz (20 CPUs), ~3.3GHz
Memory: 32768MB RAM
DirectX Version: DirectX 12
User DPI Setting: 144 DPI (150 percent)
System DPI Setting: 144 DPI (150 percent)
Miracast: Available, with HDCP

When you've connected your PC to my Xbox and are streaming FROM my PC to your Xbox, you'll see this bar at the top of the PC side. There's three optimization settings for Gaming, Working, and Watching Videos. I assume these are balancing crispness/quality with framerate and latency changes.

Gaming, Working, Watching Videos

Now let's take it to the next level. I can run Steam Big Picture and here I am running Batman: Arkham Origins on my PC, but played on and controlled from my Xbox in the other room!

I like that I don't need the SteamLink. I find that this runs more reliably and more easily than my original set up. I like that I can switch the Xbox controller from controller mode to mouse mode. And most of all I like that this doesn't require any custom setup, extra work, or drivers. It just worked out of the box for me.

Your mileage may vary and I'm trying to figuire out why some people's video card drivers don't allow this and then end up with no "Connect to a Wireless Display" option in their Win+P menu. If you figure it out, please sound of in the comments.

Give it a try! I hope you enjoy it. I'm having a blast.


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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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How to parse string dates with a two digit year and split on the right century in C#

March 7, '19 Comments [8] Posted in DotNetCore | Learning .NET
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So you've been asked to parse some dates, except the years are two digit years. For example, dates like "12 Jun 30" are ambiguous...or are they?

If "12 Jun 30" is intended to express a birthday, given it's 2019 as the of writing of this post, we can assume it means 1930. But if the input is "12 Jun 18" is that last year, or is that a 101 year old person's birthday?

Enter the Calendar.TwoDigitYearMax property.

For example, if this property is set to 2029, the 100-year range is from 1930 to 2029. Therefore, a 2-digit value of 30 is interpreted as 1930, while a 2-digit value of 29 is interpreted as 2029.

The initial value for this property comes out of the DEPTHS of the region and languages portion of the Control Panel. Note way down there in "additional date, time, & regional settings" in the "more settings" and "date" tab, there's a setting that (currently) splits on 1950 and 2049.

Two Digit Year regional settings

If you're writing a server-side app that parses two digit dates you'll want to be conscious and explicit about what behavior you WANT so that you're not surprised.

Setting TwoDigitYearMax sets a 100 year RANGE that your two digit years will be interpreted to be within. You can also just change it on the current thread's current culture's calendar. It's up to you.

For example, this little app:

string dateString = "12 Jun 30"; //from user input
DateTime result;
CultureInfo culture = new CultureInfo("en-US");
DateTime.TryParse(dateString, culture, DateTimeStyles.None, out result);
Console.WriteLine(result.ToLongDateString());

culture.Calendar.TwoDigitYearMax = 2099;

DateTime.TryParse(dateString, culture, DateTimeStyles.None, out result);
Console.WriteLine(result.ToLongDateString());

gives this output:

Thursday, June 12, 1930
Wednesday, June 12, 2030

Note that I've changed TwoDigitYearMax from and moved it up to the 1999-2099 range so "30" is assumed to be 2030, within that 100 year range.

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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Converting an Excel Worksheet into a JSON document with C# and .NET Core and ExcelDataReader

March 6, '19 Comments [22] Posted in DotNetCore | Open Source
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Excel isn't a database, except when it isI've been working on a little idea where I'd have an app (maybe a mobile app with Xamarin or maybe a SPA, I haven't decided yet) for the easily accessing and searching across the 500+ videos from https://azure.microsoft.com/en-us/resources/videos/azure-friday/

HOWEVER. I don't have access to the database that hosts the metadata and while I'm trying to get at least read-only access to it (long story) the best I can do is a giant Excel spreadsheet dump that I was given that has all the video details.

This, of course, is sub-optimal, but regardless of how you feel about it, it's a database. Or, a data source at the very least! Additionally, since it was always going to end up as JSON in a cached in-memory database regardless, it doesn't matter much to me.

In real-world business scenarios, sometimes the authoritative source is an Excel sheet, sometimes it's a SQL database, and sometimes it's a flat file. Who knows?

What's most important (after clean data) is that the process one builds around that authoritative source is reliable and repeatable. For example, if I want to build a little app or one page website, yes, ideally I'd have a direct connection to the SQL back end. Other alternative sources could be a JSON file sitting on a simple storage endpoint accessible with a single HTTP GET. If the Excel sheet is on OneDrive/SharePoint/DropBox/whatever, I could have a small serverless function run when the files changes (or on a daily schedule) that would convert the Excel sheet into a JSON file and drop that file onto storage. Hopefully you get the idea. The goal here is clean, reliable pragmatism. I'll deal with the larger business process issue and/or system architecture and/or permissions issue later. For now the "interface" for my app is JSON.

So I need some JSON and I have this Excel sheet.

Turns out there's a lovely open source project and NuGet package called ExcelDataReader. There's been ways to get data out of Excel for decades. Literally decades. One of my first jobs was automating Microsoft Excel with Visual Basic 3.0 with COM Automation. I even blogged about getting data out of Excel into ASP.NET 16 years ago!

Today I'll use ExcelDataReader. It's really nice and it took less than an hour to get exactly what I wanted. I haven't gone and made it super clean and generic, refactored out a bunch of helper functions, so I'm interested in your thoughts. After I get this tight and reliable I'll drop it into an Azure Function and then focus on getting the JSON directly from the source.

A few gotchas that surprised me. I got a "System.NotSupportedException: No data is available for encoding 1252." Windows-1252 or CP-1252 (code page) is an old school text encoding (it's effectively ISO 8859-1). Turns out newer .NETs like .NET Core need the System.Text.Encoding.CodePages package as well as a call to System.Text.Encoding.RegisterProvider(System.Text.CodePagesEncodingProvider.Instance); to set it up for success. Also, that extra call to reader.Read at the start to skip over the Title row had me pause a moment.

using System;
using System.IO;
using ExcelDataReader;
using System.Text;
using Newtonsoft.Json;

namespace AzureFridayToJson
{
class Program
{
static void Main(string[] args)
{
Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);

var inFilePath = args[0];
var outFilePath = args[1];

using (var inFile = File.Open(inFilePath, FileMode.Open, FileAccess.Read))
using (var outFile = File.CreateText(outFilePath))
{
using (var reader = ExcelReaderFactory.CreateReader(inFile, new ExcelReaderConfiguration()
{ FallbackEncoding = Encoding.GetEncoding(1252) }))
using (var writer = new JsonTextWriter(outFile))
{
writer.Formatting = Formatting.Indented; //I likes it tidy
writer.WriteStartArray();
reader.Read(); //SKIP FIRST ROW, it's TITLES.
do
{
while (reader.Read())
{
//peek ahead? Bail before we start anything so we don't get an empty object
var status = reader.GetString(0);
if (string.IsNullOrEmpty(status)) break;

writer.WriteStartObject();
writer.WritePropertyName("Status");
writer.WriteValue(status);

writer.WritePropertyName("Title");
writer.WriteValue(reader.GetString(1));

writer.WritePropertyName("Host");
writer.WriteValue(reader.GetString(6));

writer.WritePropertyName("Guest");
writer.WriteValue(reader.GetString(7));

writer.WritePropertyName("Episode");
writer.WriteValue(Convert.ToInt32(reader.GetDouble(2)));

writer.WritePropertyName("Live");
writer.WriteValue(reader.GetDateTime(5));

writer.WritePropertyName("Url");
writer.WriteValue(reader.GetString(11));

writer.WritePropertyName("EmbedUrl");
writer.WriteValue($"{reader.GetString(11)}player");
/*
<iframe src="https://channel9.msdn.com/Shows/Azure-Friday/Erich-Gamma-introduces-us-to-Visual-Studio-Online-integrated-with-the-Windows-Azure-Portal-Part-1/player" width="960" height="540" allowFullScreen frameBorder="0"></iframe>
*/

writer.WriteEndObject();
}
} while (reader.NextResult());
writer.WriteEndArray();
}
}
}
}
}

The first pass is on GitHub at https://github.com/shanselman/AzureFridayToJson and the resulting JSON looks like this:

[
{
"Status": "Live",
"Title": "Introduction to Azure Integration Service Environment for Logic Apps",
"Host": "Scott Hanselman",
"Guest": "Kevin Lam",
"Episode": 528,
"Live": "2019-02-26T00:00:00",
"Url": "https://azure.microsoft.com/en-us/resources/videos/azure-friday-introduction-to-azure-integration-service-environment-for-logic-apps",
"embedUrl": "https://azure.microsoft.com/en-us/resources/videos/azure-friday-introduction-to-azure-integration-service-environment-for-logic-appsplayer"
},
{
"Status": "Live",
"Title": "An overview of Azure Integration Services",
"Host": "Lara Rubbelke",
"Guest": "Matthew Farmer",
"Episode": 527,
"Live": "2019-02-22T00:00:00",
"Url": "https://azure.microsoft.com/en-us/resources/videos/azure-friday-an-overview-of-azure-integration-services",
"embedUrl": "https://azure.microsoft.com/en-us/resources/videos/azure-friday-an-overview-of-azure-integration-servicesplayer"
},
...SNIP...

Thoughts? There's a dozen ways to have done this. How would you do this? Dump it into a DataSet and serialize objects to JSON, make an array and do the same, automate Excel itself (please don't do this), and on and on.

Certainly this would be easier if I could get a CSV file or something from the business person, but the issue is that I'm regularly getting new drops of this same sheet with new records added. Getting the suit to Save As | CSV reliably and regularly isn't sustainable.


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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.