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As I’ve blogged a while ago (july 2019), I made my pi a docker host. I used a pi 3, but moved now to a pi 4 with ubuntu as host.

If you want to know how I did it, my collegeau Johan explains it on his blog How to install Ubuntu on a Raspberry PI – Johan the Developer and the followup How to install Docker on a Raspberry PI – Johan the Developer

Once you have that in place, you can proceed to get a Nebl Docker container.

The Nebl Docker container

I found this official one on dockerhub neblioteam/nebliod-rpi (docker.com)

The instructions are always clear at dockerhub. Step 1 is to get the image:

docker pull neblioteam/nebliod-rpi

Step 2 is to use the image to run a container:

sudo docker run -d --restart=always --name nebliod -v $HOME/neblio-data:/root/.neblio -p 6325:6325 neblioteam/nebliod-rpi


If you are less familiar with Docker, this does mount the folder /root/.neblio in your container to the folder on your docker host at the home or ~ and then neblio-data. This contains your wallet which password is generated at the 1st start of the container.


Use the container

I started a shell in the container, so it will save me some typing:

sudo docker exec -it nebliod bash

you can get your wallet address with this command:

nebliod listreceivedbyaddress 0 true


If you would not start bash first, but just run it from your docker host:

sudo docker exec -it nebliod nebliod listreceivedbyaddress 0 true


You can see that the password is random on line 16 here

docker-nebliod/neblio_init at master · NeblioTeam/docker-nebliod (github.com)

You should transfer Nebl to your wallet. It will take 24 hours to mature. Then the weight will gain for staking.

Run the nebliod getstakeinginfo to see the weight, if the coins are mature and the expectedtime in seconds for staking.

You can also use nebliod getbalance to just get the balance from your wallet without the address and confirmations which the listreceivedbyaddress returns.

So it’s all up and running 24/7 on my Raspberry Pi 4. Now it’s just a matter of time before I will receive the first stake.


If you want to know more about Neblio, please check out their website at Neblio - Blockchain. Simplified.


Good luck! I hope it’s helpful

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As I’ve previously blogged, I created a Xamarin Forms application to submit pictures of my receipts to the company I work for. But if I’d publish the app in that state, the whole world could send in receipts on my behalf. So I needed to add authentication. Because the company uses Office 365, I’d decided to add Azure Active Directory.

There are a lot of resources about Adal (Active Directory Authentication Library) Some call it Azure Adal.NET

You can read about it on the Github page

https://github.com/AzureAD/azure-activedirectory-library-for-dotnet

It is also very clear in the readme.md that you should in fact upgrade to MSAL.Net

MSAL.NET is the new authentication library to be used with the Microsoft identity platform”

Searching for Xamarin.Forms and Msal.Net did not gave me that much options, so I decided to blog about it.

MSAL stands for MicroSoft Authentication Library. The Github is https://github.com/AzureAD/microsoft-authentication-library-for-dotnet

It’s for Oauth2 and OpenID connect.

I started with adding an application registration in the azure portal under azure active directory at “app registrations”

I switched to “Single tenant” at the authentication tab/page to make sure that only people from within Partech are allowed.

Further more you need to write down the app (client) id and the directory (tenant) id.

Next was the code integration:

1. add nuget ‘Microsoft.Identity.Client’ to the Xamarin shared app

2. make sure your app.xaml.cs looks like this:


public static IPublicClientApplication PCA;
private const string applicationClientId = "clientidhere";
public static string[] Scopes = { "User.Read" };
public static string Username = string.Empty;

public static object ParentWindow { get; set; }


public App()
{
	PCA = PublicClientApplicationBuilder.Create(applicationClientId)
		.WithTenantId("tenantid here")
		.WithRedirectUri($"msal{applicationClientId}://auth")
		.WithIosKeychainSecurityGroup("com.microsoft.adalcache")
		.Build();


	InitializeComponent();

	MainPage = new MainPage();
}

3. to the mainpage I added an override of OnAppearing which called an async CheckAuth

4. add this code to checkauth:


AuthenticationResult authResult = null;
IEnumerable accounts = await App.PCA.GetAccountsAsync();
try
{
	IAccount firstAccount = accounts.FirstOrDefault();
	authResult = await App.PCA.AcquireTokenSilent(App.Scopes, firstAccount)
						  .ExecuteAsync();
}
catch (MsalUiRequiredException ex)
{
	try
	{
		authResult = await App.PCA.AcquireTokenInteractive(App.Scopes)
								  .WithParentActivityOrWindow(App.ParentWindow)
								  .ExecuteAsync();
	}
	catch (Exception ex2)
	{
		DisplayAlert("Acquire token interactive failed. See exception message for details: ", ex2.Message, "Dismiss").RunSynchronously();
	}
}

if (authResult != null)
{
	await GetHttpContentWithTokenAsync(authResult.AccessToken);
}

5. for the rest of the code to retrieve the users given name, surname etc. you should check the GitHub link I mentioned previously.

To do more with azure AD use the Graph explorer

Good luck coding!

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There was an email earlier this year about a change in declarations from my employer. You can’t just drop receipt on someone’s desk anymore, but since we are in a digital era, we should make a picture of it and send it by mail. That sounds fair. But that would require me to remember the constraints, like letting know for which client it is and to which address I should send it to. So I decided that it needed automation.

Because some coworkers have iPhones and some have Android, I decided to go for this approach:

architecture

Xamarin Forms (Android, iOs) post a picture of a receipt to Azure Functions in the Azure cloud which sends it to Sendgrid. (Because Azure Functions cannot send mail)

Here are the steps I took to make a simple camera app:

1. File, new project, new Xamarin Forms project (no web api)

2. Add new project to solution (Azure Functions)

3. Add the nuget package ‘Xam.Plugin.Media’ to the shared/main xamarin project

4. Add UI code:



        

5. Add code to cs (code behind file)

I had three class variables (type string) filePath, filename, url (url to your azure function) I forgot that the emulator is a vm so you can’t use the localhost if you are testing the Azure Function but you should use your LAN ip.


private async void takePhoto_Clicked(object sender, EventArgs e)
{
	if (!CrossMedia.Current.IsCameraAvailable || !CrossMedia.Current.IsTakePhotoSupported)
	{
		await DisplayAlert("No Camera", ":( No camera avaialble.", "OK");
		return;
	}
	filename = DateTime.Now.ToString("yyyyMMdd-") + Guid.NewGuid() + ".jpg";

	var file = await CrossMedia.Current.TakePhotoAsync(new StoreCameraMediaOptions
	{
		PhotoSize = PhotoSize.Medium,
		Directory = "Sample",
		Name = filename
	});

	if (file == null)
		return;

	filePath = file.Path;

	image.Source = ImageSource.FromStream(() =>
	{
		var stream = file.GetStream();
		file.Dispose();
		return stream;
	});
	sendPhoto.IsEnabled = true;
}

private async void sendPhoto_Clicked(object sender, EventArgs e)
{
	HttpContent fileStreamContent = new StreamContent(File.OpenRead(filePath));
	fileStreamContent.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("form-data") { Name = "file", FileName = filename };
	fileStreamContent.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/octet-stream");

	using (var client = new HttpClient())
	using (var formData = new MultipartFormDataContent())
	{
		formData.Add(fileStreamContent);
		var response = await client.PostAsync(url, formData);
	}
}

6. add `await CrossMedia.Current.Initialize();` in the android project in the mainactivity.cs just below the OnCreate call

7. add this code to the azure function:


string imageBase64;

using (var ms = new MemoryStream())
{
	file.CopyTo(ms);
	var fileBytes = ms.ToArray();
	imageBase64 = Convert.ToBase64String(fileBytes);
}

string sendgridApiKey = "api-key-here";

var client = new SendGridClient(sendgridApiKey);
var from = new EmailAddress("mymailaddress@partech.nl", "JP Hellemons");
var subject = "Declaraton from app";
var to = new EmailAddress("mymailaddress@partech.nl", "JP");

var msg = MailHelper.CreateSingleEmail(from, to, subject, "plain msg", "html version");
msg.AddAttachment(file.FileName, imageBase64, "image/jpeg", "attachment");
var response = await client.SendEmailAsync(msg);

return new OkObjectResult("");


8. of course make a free account at sendgrid and just follow the tutorial/docs for adding the nuget package to the Azure Function.


Next post will contain a link to the Azure Active Directory for authenticating so that not everybody will send in receipts on my behalf.

Good luck!

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I followed this guide: https://medium.com/@tsjdevapps/use-fontawesome-in-a-xamarin-forms-app-2edf25311db4

Where you manually have to edit a XML file to get it to work in iOS and add the font for each platform you want to support. So for FontAwesome (regular, bold, brands) and UWP, Android, iOS. That gives 9 files!

which eventually works:

<Label Text="&#xf0f3;" FontFamily="{StaticResource FontAwesomeRegular}" FontSize="Large" TextColor="Red" />
         <Label Text="&#xf26e;" FontFamily="{StaticResource FontAwesomeSolid}" FontSize="Large" TextColor="Red" />
         <Label Text="&#xf26e;" FontFamily="{StaticResource FontAwesomeBrands}" FontSize="Large" TextColor="Red" />


BUT: If you would just update to Xamarin Forms 4.5.0.530 or higher

you can add a line for a font. (so 3 times something like this for FontAwesome)

[assembly: ExportFont("FontAwesome5Regular400.otf", Alias = "FontAwesome")]

to your app.xaml.cs

and use

<Label Text="&#xf0f3;" FontFamily="FontAwesome" FontSize="Large" TextColor="Green" />

in your mainpage.xaml


good luck!

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In my previous post I thought that I would not make the app because I did not had a nice geocoding service. I did find Azure Maps, but there is no nice C# client at that time and I did not feel like doing manual REST calls. I know I can, I just didn’t feel like making it (sorry).

So I’ve worked in the past with the Geocoding.Net Nuget packages and decided to go for the Bing version. Googles version requires an account with billing because the first 200 dollar is free. It does feel like a hurdle for me as I do not work that much with Google Services.

So I did create an Azure Function which reads the kmz and extracts it to kml and for each unknown placemark would do a geo-location and store it in a file, so that only new bears would require a call to the Geocoding service of Bing.

The app is up now in the play store. Not in Apples App store, because I did not buy a license for it.

https://play.google.com/store/apps/details?id=com.companyname.bosscheberenbingo

I forgot to rename the package.

Here is a small snippet for the Geocoding:

var geocoder = new Geocoding.Microsoft.BingMapsGeocoder(“key”);

var geoCodeResponse = await geocoder.GeocodeAsync(“address here”);

var location = geoCodeResponse.First().Coordinates;


Good luck and happy bear hunting!

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