Building transactional web application using SharePoint

Question

Disclaimer: I do no have extensive SharePoint/.NET experience, mostly read through online Microsoft docs, so asking opinion in this forum.

I am modernizing 2 legacy microsoft apps. One is SharePoint 2013 site used for CMS and other is ASP.NET 2.0 web application having transactional frontend. New combined frontend must be JS based common for all screen sizes. Business wants most cost-effective solution, preferably on-prem. I am bit confused about the approach to unify both. 1) Upgrade path - Put ASP.NET into SharePoint farm and then modernize the UI pages. 2) Rewrite with SharePoint frontend - Build using SharePoint Framework (SPFx) which internally supports modern JS frameworks. 3) Rewrite without SharePoint frontend - Build a common JavaScript UI portal (ReactJS) and access the backend REST APIs (including SharePoint) sitting behind an API Gateway.

Answer 1

For Cost effective solution, don't use spfx / ReactJS. Their development environment settings are costly and expired in sometime by new version sooner.

One can rewrite using jsom in SharePoint online , as SharePoint online provides a very good code editor . JSOM all operations are below : https://www.codesharepoint.com/jsom/0/all-methods

Answer 2

Approach 1 (ASP.Net in SP Farm) - I would not consider this 'modernizing' as Microsoft's approach going forward is using front-end javascript based applications, which are extremely powerful with the amount of AD integration/Graph libraries/etc. made available. This feels dated in my eyes and could create issues down the road if the company ever wishes to migrate to SharePoint Online.

Approach 2 (SPFx) - This is where the Microsoft ecosystem is flowing with SharePoint modifications. It's also easy to tie into back-end services or other services using Azure App Registrations. There is a lot of flexibility here, you have the option to use ReactJS as well, among other frameworks. I would recommend this approach

Approach 3 (Custom App) - I have built solutions running off create-react-app and similar frameworks and I still try to leverage SharePoint if it is a significant part of the ecosystem as they have very powerful frameworks for tying into it such as PnPjs. It just makes integration so much easier, and you are working within the context of SharePoint vs a custom application on some other server which must be wary of authentication as well as the potential need of a back-end service for communication to SharePoint.