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Use code on one device and show 'result' with others using push notifications

I am using HTML Agility pack in Xamarin forms to scrape data from a website. When a condition returns true, I want to send a push notification to all users. However, this data is changing a lot and I think it would cost a lot of internet data and maybe battery, if the device with this app is constantly collecting the data in the background to check a certain condition.

This is a piece of the code to give you an idea:

var url = "https://www.goal.com/en-us/live-scores";
var httpClient = new HttpClient();
var html = await httpClient.GetStringAsync(url);
var htmlDocument = new HtmlDocument();
htmlDocument.LoadHtml(html);

var voetbalWedstrijdenHTML = htmlDocument.DocumentNode.Descendants("div").Where(node => node.GetAttributeValue("class", "")
        .Equals("main-content")).ToList();

So I thought it might be a good idea to let only one device use this code and check if the condition is true and then only send the push notification to all users. I've made this image to give you a better idea about what I mean.

notifications

I thought it might be a good idea to use firebase messaging to send push notifications to all users, but how or what do I use to have only one device checking the C#? Should I use a website with the C# code that is running 24/7 (is this possible?), or something else? So... how do I run C# code 24/7?

EDIT:

I found out about 'Firebase functions'. Would this work for me? I'd have to change to javascript so I rather stick to C#.

like image 205
J.K. Harthoorn Avatar asked Jul 23 '19 22:07

J.K. Harthoorn


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1 Answers

Here's how i would have done it

  1. Create an Azure web job that checks the condition. You can schedule it to run according to your requirements.

  2. Create an Azure notification hub (ANH) and link it to Firebase and equivalent in IOS and other platforms as per requirements.

  3. Create a web api that every app user will call. In this api call, register every device with Azure notification hub. The registrations can include tags to which you can send notifications to.

  4. When the web job needs to trigger a notification, it will call the ANH directly or through the web api and send a broadcast notification. You can also narrow down the users to send notifications based on tags.

One advantage of using ANH is that you don't need to worry about sending to multiple platforms. You just send to tags it will go corresponding users of all platforms.

I believe that this document may help you. https://learn.microsoft.com/en-in/azure/notification-hubs/. Hope I have helped.

EDIT:

Would you be using 2 projects: Yes you would be using atleast 2 projects. One for web api and 1 for each platform that you want your app to be in.

Point in Using Azure Notifications: It comes with great deal of features that will make your life easier especially if your application runs on multiple platforms. However, you can use FCM directly. Actually ANH will also use FCM behind the doors.

Putting the code you want to run every some time in Startup.cs: Thats a bad idea. You should ideally be using a web job for that. Startup code is executed only once in lifetime of application. You don't want your notification trigger code to be in Startup class. However if using webjob is not something you want, you can be using the cron scheduler.

EDIT 2:

You can use the timer in Startup.cs however, i would not recommend that. One class should ideally have only one purpose and business logic is not for Startup. You should consider moving out the method to another class.

If you decide to use webjobs, you would create different projects for web job. These offerings like ANH, web job etc exist for one reason - to make your life easier. You can always do everything on your own if you are ready to work extra mile. PS web job is becoming obsolete and people are now moving to Azure functions.

like image 173
It's a trap Avatar answered Oct 24 '22 13:10

It's a trap