Introduction

What is Nidus?

Nidus is a state-of-the-art modular framework for building enterprise backend applications and microservices in Delphi (Object Pascal). Its design is deeply inspired by NestJS, bringing the same separation-of-concerns philosophy and structural conventions to the Delphi ecosystem.

Design philosophy

Modules as first-class citizens

Every feature lives inside a TModule subclass. Modules declare their own providers (services), import other modules, and export providers to consumers. This mirrors the NestJS module pattern and keeps large codebases maintainable.

Inversion of control via Dependency Injection

Nidus includes a built-in DI engine (TCoreInject) that automatically resolves constructor dependencies, manages object lifecycles (Singleton, SingletonLazy, Factory), and wires the application graph at startup.

Declarative validation via RTTI decorators

Request DTOs are annotated with RTTI attributes ([IsEmail], [IsNotEmpty], [IsStrongPassword], …). The global TValidationPipe inspects incoming requests and rejects invalid payloads before any service code runs.

Guards for access control

UseGuard accepts a callback that returns Boolean. If it returns False, Nidus raises EUnauthorizedException (HTTP 401) before the route handler is invoked.

Addons: pooling, caching, RPC, message bus

Beyond the HTTP request pipeline, Nidus provides first-class addons for high-throughput scenarios:

• Object pooling — reuse expensive objects or TComponent instances across requests.
• Module caching — keep module instances alive across requests to avoid repeated construction.
• RPC microservices — publish named handlers over a TCP socket (Indy or Synapse adapters).
• Message bus — in-process pub/sub with wildcard topic matching.

Architecture overview

Application bootstrap (GetNidus / TNidus)
  │
  ├── UseListener   → TAppListener  (structured log)
  ├── UsePipes      → IValidationPipe (global RTTI validation)
  ├── UseGuard      → TGuardCallback  (authorization)
  ├── UseCache      → IModuleCache    (module-level caching)
  ├── UsePools      → IPoolRegistry   (object / component pools)
  ├── UseRPC        → IRPCProviderServer (TCP microservice server)
  │
  └── Start(TAppModule)
        │
        └── TModule tree (imports / providers / services)
              │
              └── Route handlers → LoadRouteModule(path)

Key source units

Unit	Role
Nidus.pas	TNidus facade — the single entry point for application configuration
Nidus.Inject	TCoreInject — wires the internal DI container at startup
Nidus.Module.Provider	Walks the module tree, registers routes, manages lifetimes
Nidus.Driver.Horse	Horse middleware adapter (Nidus_Horse)
Nidus.Module.Cache	TModuleCacheManager — thread-safe per-module cache
Nidus.ObjectPool	Generic TObjectPool<T> with acquire/release semantics
Nidus.RPC.Publish	TRPCPublish — RPC name→class registry
Nidus.Message.Bus	TMessageBus — in-process event/pub-sub