How to modify presence subscriptions workflow on ejabberd server? - erlang

I am developing something with ejabberd server. I came to the need of changing the subscription logic. I am using ejabberd-2.1.11
My need is on how the subscription works, I would like to change the logic so that users upload their roster contact with subscription both automatically and and save in in the rosterusers table-colum subscription immediately to be B. So that they should be able to see online and in their contacts at least when the first one has already registered to the server. ( hope this make sense for you and is valid)
I am a very beginner in erlang and ejabberd architecture but I have already developed some basic modules, my question to you is if you could help me on this regard, how difficult is to make this change and if you could give me some hints where the changes would be

I'd stay away from modifying the server, it conforms to standards and follows the specification. So if you ever need to move to another server or upgrade, you know it's just going to work.
What you would do to achieve this is implement this behavior on the client using the server's features.
If you are really sure you want to modify the server, mod_roster.erl is the file you want to be looking at.
If using an external DB, you can also modify the DB directly, but changes won't be reflected until the clients log back in.

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Consuming Webhook payloads in Vue/Pinia in real time

So, i'm relatively new to Vue, and I'm currently using it to build a small app that displays order data from Square's API.
I'm currently working on a stack that uses rails to make api calls using the square.rb gem. The frontend is entirely Vue which uses Pinia as a store, and there isnt going to be any kind of database behind this because reasons.
All data is provided directly via Square's API. I am currently polling to update order info, but my client wants to make this app truly real time, as it deals with food deliveries through ride-share companies and the purpose of this app is to show in real time statuses of orders for an in house screen at the restaurant.
Now Square has a webhook subscription service, and based on my reading it sounds like I can consume these to update my app, but there are a few logical leaps that I havent been able to make yet with how to get that data to the frontend of my app.
My questions are the following, with the intent being to connect the dots between the different technologies I might need to employ here to make this work. Kinda get a sense of what i'd need and where to link it up.
Can I use vue to consume webhook payloads directly and update through reactivity? That would be ideal, but I have found no docs yet that give me a good idea of whether thats possible.
If that is not possible, do I need to use some sort of socket connection (socket.io) to listen for these webhook updates?
If the current setup or proposed setup in the questions above is not feasible, what is a better solution for handling this while still using Vue?

Need advice on syncing data between iOS devices in one app

I built an in-house app for selling tickets and checking-in students to our High School dances. At the moment the app can scan a QR code with the student's information and add their name to either a "Sales" list or "Check In" list. Then the app can export these lists to a CSV file and we compile all the data.
App works perfectly as expected. NOW I want to be able to sync data between multiple devices so that every device will see an up to date Sales and Check in list. The check in list is most important because then our faculty chaperones can all see who has arrived to the dance in real time. I figured I would need to build a server to hold all the data as opposed to on the individual devices like I am doing now (CoreData). Can anyone please give me guidance or advice as to where to go from here? I am using Swift and developing for iOS 10.
I would just answer the general approach to tackle this problem since the implementations would largely be depending on many factors (what database technology is available, the platform of the server, etc.)
You are absolutely right, you need a server to hold the data. Technically speaking, it is a database that holding the data. Thus, you need a database running on your server (there are tons of selections here: Maria DB, SQL Server, Mongo DB, etc.).
Next, you need to build a web service on top of the database so that the iOS app can interact with the database (add/delete/update/read rows). Web service is a very common layer in full-stack application since you normally don't access the database directly.
Finally, you need to guard your web service with some sort of authentication. I.e. you don't want any random person out there to be able to access your web service without permission. There are many implementations out there to secure your web service and you should be able to google that easily.
Firebase might be the easiest solution. Its pretty simple to setup, and its pretty simple to set up data persistence when you go off line. I'm big on trying to stick with the built in Apple services, but Firebase is hard to beat for simple apps.
Take a look at CloudKit, or perhaps Firebase or Azure, as services that will provide a back end server for you, and give you a tested SDK to build against.

Anonymous contact form iOS app

I currently work at a school and have an idea to create an app that allows students to contact a grown up (for example, the principle) anonymously through an app. The app would quite simply consist of a contact form. I am trying to find out the best, and easiest way to achieve this without setting up servers with a separate API. Does anyone have a suggestion on how to achieve it? Is there any way to set up an e-mail form with a pre set recipient and a built in sender-account? Please guide me in the right direction.
You would need to implement an SMTP client. You can use open source code like skpsmtpmessage
It's likely that their example app could be your solution.
Your biggest problem will be the deployment. You definitely need to pay an $99/y developer account and add all the students device ID's to your account (with a maximum of 100 devices/y) or register all of them as beta tester (I don't know the limitations).
Probably this isn't doable so easily, as it seems you don't have iOS developing experience so far. Maybe you can find something on the app store that works with self hosted databases. But you definitely need to host some kind of webApp/API.
You may want to give Appygram a try to handle the back-end if you are able to set up the contact form itself. While it's a separate hosted API, at least you don't have to build/manage it.
Appygram is a free web service that would allow you to configure all the details such as which adults could be contacted, their point(s) of contact (i.e. email address), and it would process and send all the submissions for you. All your app needs to do is send a form post request.
A nice thing about having this information outside of the iOS app itself is that you can change the contact details on the fly without requiring an update to the iOS app itself. Whether you use Appygram (which, since I contribute to it, I am slightly biased toward!) or something similar, I would say that since this is for students, I would recommend a solution that would allow you to update your configuration without requiring app updates.
Finally, I'd second what Julian said. The challenge here could be with deployment. One possible alternative would be to make this a mobile-friendly web page accessible only via student login or on the school network (or both). Would probably be easier development-wise and wouldn't require installs nor the hurdles that Julian described with device registration, etc. And, Appygram would still work with this setup as well.
Good luck!

Core Data Sync With Multiple Users

I would like to sync a core data app with a user with a different iCloud ID and I am trying to figure out the most graceful way to do this. I do not want the data to sync with all users, but want to be able to sync among family members for instance. From the research I have done, I do not think I can do that using iCloud Core Data sync because it only syncs between devices with the same iCloud ID. I have looked at this stackoverflow answer and read a little bit about Ensembles, Parcelkit and TICoreDataSync, Parse etc., but it is not clear to me if any of those options will allow me to sync with multiple users. Does anyone have a good method for syncing a Core Data app with multiple users?
Ensembles and TiCoreDataSync might work. They can use Dropbox file syncing, so in principle they should work with Dropbox shared folders. I don't think these are the main intended uses, so I suggest contacting the developers and/or doing some good testing yourself before assuming this would actually work.
You'll need to think about the user experience, though. At a minimum, your users would both need Dropbox accounts and would have to set up a shared folder before beginning to sync data this way.
Parcelkit probably won't work. It uses Dropbox's data store API which, unlike other Dropbox services, doesn't appear to support shared data.
Services that do support this kind of sharing exist-- for example, Parse and Firebase-- but make sure to review their pricing carefully before using them. Also of course, there have been any number of projects that have their own custom server back end, but that obviously requires having someone on the team who can do that kind of work.
You need to think about other device types (Android at least) if you want your application to be reaching more users.
I'm doing the same now by the following way:
Setup an online database with proper web services (careful with implementation for security matters - DB should NEVER be exposed by anything other than the web services).
Create a Class for your communication with the server (using Class methods with security handling like authentication and authorisation).
Use the class in your app to communicate with the server (SQL operations are done on the server).
To integrate with CoreData you need to create the model in your app similar to the structure in the backend database. Then you need to create a similar class for the app that deals with only local CoreData.
A higher level class might be required if you want to make sure that operations done on both server and local data storage.
Besides, you have to implement a lot of conditions to make sure that data written in local ONLY after making sure that it is stored online (or create an engine for differed operations to run later).
Another Way if you are familiar with notifications:
Use structured notifications between devices for data operations in order to keep everything in sync with other users. The problem with this is the "Autonomy" of the operations. If two operations were done in approximately the same time, you have to find a way to make sure the order of the operations is done properly (maybe timestamp or something).
I'm looking into the same thing for my app and I 'think' you can do a fairly unsecured version of what you are after using using the public folder in cloud kit as mentioned in this question (no accepted answer at time of posting) : Private data sharing using CloudKit
You would need to find a way to differentiate between data that is truly public and those shared among the users you need and some level of authentication.
I'm going to try exporting a permission file with access permission in it to whomever I want to share with combined with a unique identifier located in that permission file.
Keep in mind, as mentioned in the comments of the linked answer, my implementation will be security by obscurity (thanks for that phrase) unless you find a way of adding proper validation to it but my data is relatively insensitive.
Hope this, or any ridicule in the comments, points you in the right direction : )

How to get User Data from the App?

Is there a way to get data from the user while they use my app on their device (iPhone/iPad). For example, if the app fills a dictionary during the runtime about which avatar is used most of the time and which avatar not, is there a way to transfer that dictionary to me? Do I need a server?
This is my first time thinking about data transfers over the internet. I don't have any idea or any experience on how to do that. Somehow I feel it is impossible for some security reasons. I found the NSURLConnection class, but this seems to be only one way to move data from a server to the app.
Thanks.
Not sure if I fully understand the question, but I am assuming you would like to get information about how the user is using your application?
This is definitely possible; and yes, you will need a server to send, retrieve or store the information that you require, or else there is no way to get the data from the application to you! You will need to learn how server side and client side web scripting works (if you do not know already) as this is how the application will communicate with your server.
Depending on the kind of information you are trying to retrieve, there may be security issues and Apple may not accept your application. However, if your data is specific to your application features, there should be no issue of this kind.
HTH

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