System architecture design advice

Question

We are working on the design for an appointments system which has to work at remote locations, comms via 4G.

Unfortunately a connection to the server may not be available at all remote locations, so data must be pre-downloaded before departure to the off site location, just in case.

The UI should be presented on mobile devices and ideally, be device agnostic so the customer isn't tied to a single device. html - in the device browser, in an 'app' wrapper, or cross platform development tool (cordova, phone gap, xamarin etc)

We originally designed a system with a server (windows or linux laptop) which would be taken out containing a local database and running a web server providing a web app solution.

We are now looking for a design which would not require the laptop to be taken to the locations - just mobile devices.

Data would therefore need to be stored on each device?, the complication being that if a person was booked into an appointment on one device the other devices should be sync'd so any member of staff can deal with the person.

Requirements

Mobile devices. Device agnostic if possible Online or offline (seemless). Data sync'd between devices even in offline mode (ie no connection to Internet, but local WiFi available)

We have .Net, android, html, javascript experience. Back end server will be webapi on Azure.

Answer 1

You might want to think about creating a Progressive Web App(PWA). It is a web page that has some functionality of an app when it comes to limited to now connectivity. You can run it on a desktop browser and mobile browser, assuming it is built responsively.

What will be needed is to build how to browsers service worker interacts with the server and how it should function when there is no connectivity. Also, you will have to persist data locally, then once a connection is established, send any new data to the server. This can all be done via Javascript client side.

Here is a link to more about Progressive Web Apps.