Introduction

MARS-Curiosity is a lightweight, Delphi-native library for building RESTful web services and the clients that consume them. It targets recent Delphi versions (from 10.4 up to 13 Florence; older versions back to XE7 are largely compatible) and runs on Windows and Linux.

Why MARS?

REST is the lingua franca of modern application integration. MARS lets you expose business logic written in Delphi as clean, standards-compliant REST endpoints — consumable from web front-ends, mobile apps, .NET, Java, PHP, or any HTTP client — and to write Delphi clients against any REST server.

The library is built around six guiding principles:

1. Lightweight — no constraints on your application architecture and no heavy dependencies. You include only the units you actually use.
2. Easy and powerful — a small, attribute-driven API that scales from a one-method "hello world" to large, secured, data-aware servers.
3. Pure RESTful Web Services — interoperable with any consumer technology.
4. Delphi-like — leans on modern language features (custom attributes, generics, RTTI, anonymous methods) on the server, and a classic RAD component model on the client.
5. Advanced dataset support — deep FireDAC integration for Delphi-to-Delphi data-aware applications.
6. OpenAPI 3 support — automatic specification generation and Swagger UI.

How it works in one minute

A MARS server is organized as a small hierarchy:

• An Engine hosts the server and routes every incoming HTTP request.
• One or more Applications group related resources under a base path (e.g. /default).
• Resources are ordinary Delphi classes decorated with [Path]. Their methods are decorated with HTTP-verb attributes ([GET], [POST], …) and become your endpoints.
• For each request, MARS creates an Activation: it selects the resource and method, checks authorization, injects parameters, invokes your code, and serializes the result.

HTTP request ─► Engine ─► Application ─► Activation ─► your resource method ─► response

You never write request-parsing or routing code. You declare what an endpoint is with attributes, and MARS does the plumbing.

Server and client, both included

MARS ships two complementary parts:

• MARS Server — the units under MARS.Core.*, MARS.Data.*, MARS.OpenAPI.*, etc. Host it in a console app, a Windows service, a VCL/FMX app, Apache (mod), ISAPI, FastCGI, or as a Linux daemon.
• MARS Client — a set of runtime/design-time components (TMARSClient, TMARSClientApplication, TMARSClientResource*, TMARSClientToken, …) for consuming any REST API from Delphi, with first-class support for MARS servers (including FireDAC dataset sync).

What's next

• Install MARS into your RAD Studio IDE.
• Build your first server.
• Understand the Core Concepts before diving into the Server and Client sections.