Develop Reference

How to publish React JS PWA in Amazon app store?

I am creating a React JS PWA web app, so that the users can install it on their mobile devices. Now the client ask to find out a way to push these PWA apps to amazon app store. So my query is whether we have tools for converting the Progressive Web Apps as APK or HTML5 Web app files so that we can put them to amazon app store.
I googled a bit and I am confused, but I am not sure which one is the right one to use and whether we can publish a PWA app to the amazon app store
Any help on this will be very grateful.
Thanks.

PWA needs a browser to be executed. So if you want yo package your pwa as apk(android) you will need to implement a kind of mini-browser with pure android.
Fortunately, this task is very common and there are even online services to do that:
https://appmaker.xyz/pwa-to-apk/
https://pwatoapp.com/
Or if you know java:
https://github.com/xtools-at/Android-PWA-Wrapper
Or c++
https://github.com/RikudouSage/PwaToTwa
Or nodejs
https://github.com/pwa-builder/CloudAPK

You can use the Amazon Web App Tester to verify how your Web app behaves when Published to the Amazon App Store: https://developer.amazon.com/docs/fire-tablets/webapp-app-tester.html
If it performs correctly in the tester, you can then publish the URL directly or upload your files. The full process is described here: https://developer.amazon.com/docs/app-submission/publish-app-webapp-files.html

equivalent ios library for RTCMultiConnection in java script

I am working on webRTC iOS integration. Our Web team integrated the webrtc using RTCMultiConnection library (https://cdn.webrtc-experiment.com:443/rmc3.min.js) and created the Web Application. They are setting the socket url (server url) and configuring the library objects and creating the session using the library.
Is there any equivalent library for making the connection directly from client? Or is it possible to access the .js file from swift?

Please check the RTCMultiConnection-API:
https://github.com/muaz-khan/RTCMultiConnection/blob/master/docs/ios-android.md
Above doc explains how to create a cordova-based iOS/Android application.
Everything from RTCMultiConnection-v3 is supported in cordova-apps except "Screen-Capturing". You can NOT capture your screen from any iOS/Android app.
The ONLY_Disadvantage of Cordova_based_apps is "It adds 20MB unwanted Size in the compiled iOS/Android app" .... i.e. your APK file may have 20MB minimum size.
Here is an example APK file (android-application using RTCMultiConnection v3):
https://play.google.com/store/apps/details?id=com.webrtc.experiment

https network call ssl implementation using Javascript (Cordova)

In my cordova application, I am using https api calls using java script. In android platform it is working as expected. But the iOS api was not working with my iPad. When I investigated more, I found that it is related to ssl habndshake. I have added the following method to my app delegate
#implementation NSURLRequest(DataController)
+ (BOOL)allowsAnyHTTPSCertificateForHost:(NSString *)host{
return YES;
}
Now the api is working fine. But came to know that this is not recommended when application is uploaded to iTunes store. In native applications apple recommends to implement NSURLProtectionSpace api. I wish to know how this can be accomplished in cordova platform?

Database for 2 android apps (one Java, the other Javascript)

I'm currently developing an app (via Intel XDK) that reads a .csv file that was created by another app (via Android Studio). The Android Studio app is mainly for capturing sensor data, whereas the Intel XDK app should display the data fancily. Since saving everything as .csv and reading it all later on is incredibly naive performance and storage-wise, I was thinking about creating a database that manages the data. Now, setting up a database for each app seems easy enough, and there are also solutions for two Android Studio apps. But how can I create and manage a database that can be used by an Android Studio as well as by an Intel XDK app?

OK, I think you want to have your Native Android Database to be accessible from another Application so your solution will be ContentProviders.
You should build a ContentProvider layer above your SQLite database in the native android application then you can easily contact the ContentProvider from any other application included PhoneGap or any cross platform one.
To learn more about ContentProviders in android check that.
To learn how to expose or use ContentProvider from CrossPlatform phonegapp applications check that.

You can use the Content Provider mechanism of Android, as described in http://developer.android.com/guide/topics/providers/content-providers.html.
You decide on one of the two apps to actually manage the database and play the role of content provider to the other. The other accesses the data via the interface provided by the content provider.
This works if both apps are on the same device. For cross-device synchronization of data look at Couchbase Lite, a database that offers this feature out-of-the-box.

HTML5 Android Development

I am interesting in making an android application, while my primary hobbies is web development. Now the thing that is confusing me is that people make applications in HTML5/CSS3/JavaScript languages, are those apps running on web browsers on android mobile or running like an installed application on android?

Well you can design and develop your app in 3 ways
Native: full Java code in Android case, or Objective-C or Swift now in iOS
Web: HTML5, CSS3, JavaScript
Hybrid: a mixture of the two
If you are a web developer you can design your app in HTML5 and then use a wrapper like PhoneGap or Apache Cordova which will simply wrap or package your app in a WebView (a Webview is like a simple browser inside a native app).
Then you will have your APK like any other app in Google Play, so yes it's a full application that can be installed, updated and deleted of course, in any Android device
But there is a difference between the two, like the speed varies depending on the app type:
previously, web apps couldn't gain access to the accelerometer, camera, gyroscope etc, but now with the bunch of APIs available, you do have the ability to access them in very simple ways.
A full definition of a webView
The WebView class is an extension of Android's View class that allows
you to display web pages as a part of your activity layout. It does
not include any features of a fully developed web browser, such as
navigation controls or an address bar. All that WebView does, by
default, is show a web page.
More info about WebView Here

Yes they can be opened in web browsers. Those mobile application that is written in HTML5 are really web applications that have Mobile user interface. You can create and experience these projects using Visual Studio 2012. Go to new project -> Web -> ASP.Net MVC 4 Web Application -> in "select a template" choose Mobile Application