How to do a REST webserver with Delphi as a backend for a big web application?

FireHttp is a high-performance Web server based on Delphi/Object Pascal language. It supports HTTP 1.1, HTTPS (SSL/TLS), WebSocket, GZip, Deflate, IOCP, EPOLL. It adopts multi-process+multi-threading model, has good stability and concurrency performance, and provides SDK source code. Developers can use SDK to quickly build high-performance cross-platform Web applications.

To create your REST services, try our Open Source mORMot project. Now it is a well known and stabilized project, used world wide in production.

You can use any DAC with the current state of the framework by implementing a custom TSQLRestServerStatic class (similar to the TSQLRestServerStaticInMemory class, but calling your DAC): so you'll benefit for the ORM and the JSON RESTful architecture, together with the high-speed http.sys kernel-mode server.

The SQLite3 engine is NOT mandatory with our framework, even if it was designed to work better with it.

I think you should have a look at kbmMW, there is a way to implement a basic REST server based on an event driven HTTP server.

Check news.components4developers.com news groups, there you will have a lot of documentation.

If you will start an application from scratch, I think the mORMot is a good option if Delphi is your only option. If you choose datasnap you'll have to live with the problems of performance and stability.

I wrote an article on my blog talking about performance and stability with DataSnap (and mORMot) in large applications, you can see it on the following link:

DataSnap analysis based on Speed & Stability tests