name: ACBr Project Patterns description: Architectural, dependency injection and UI patterns for the ACBr Project (Commercial Automation Brazil) ecosystem in Delphi.

Standards for ACBr Project

The ACBr Project is vital for issuing NFe, CTe, NFCe, SAT, TEF and controlling fiscal/non-fiscal scales/printers in Brazil. It contains fantastic components, but due to its background and history of strong VCL coupling that accompanies older developers, the best practices below ensure maintainability in modernizations.

1. Rule of Thumb: No Strong Visual Coupling

Do not instantiate components TACBrNFe, TACBrCTe, TACBrPosPrinter, etc., directly in the View Forms of the interface (.dfm/.fmx). This breaks the clean architecture, MVC and makes unit testing immensely difficult.

O Que Fazer?

Create Service "Wrapper" classes or Infrasctructure Repositories that inject (via constructor or Service Locator) the system configurations to the Fiscal Engine.

type
  INFeEmissor = interface
    ['{GUID}']
    function EmitirNota(ANota: TBaseNFeModel): TEmissionResult;
  end;

  TNFeEmissorACBr = class(TInterfacedObject, INFeEmissor)
  private
    FAcbrNFe: TACBrNFe;
    FConfig: IAppConfig;
    procedure ConfigureComponent;
  public
    constructor Create(AConfig: IAppConfig);
    destructor Destroy; override;
    function EmitirNota(ANota: TBaseNFeModel): TEmissionResult;
  end;

2. Abstracting Signing and Cryptography Libraries (OpenSSL vs WinCrypt)

It is a documented good practice to also isolate the libraries for each OS version if the project is cross-platform or supports VMs (e.g. Linux Docker vs Windows). Configure this Always via code dynamically within the wrapper referenced in Session 1, never at fixed design-time, using LAcbrNFe.Configuracoes.Geral.SSLLib := libWinCrypt; (or OpenSSL).

3. Handle Callbacks and Events (ex: TEF)

ACBrTEFD works heavily based on VCL events (OnExibeMensagem, OnAguardaDigitacao). Implement them by sending native bus events or defining a generic UI "Handler" injected into the class so that the component code remains in the Business/Gateway Layer, delegating only the "Draw to Screen" to specific interfaces that can be overridden in Headless/REST API scenarios.

  ITefPresentationHandler = interface
    procedure ShowTefMessage(const Msg: string);
    procedure ClearTefMessage;
  end;

4. Dynamic Memory Management

If you instantiate sub-function components (e.g. ACBrCEP) dynamically, avoid memory leaks.

function RetrieveAddress(const AZipCode: string): TAddressResponse;
var
  LCepComponent: TACBrCEP;
begin
  LCepComponent := TACBrCEP.Create(nil);
  try
    LCepComponent.WebService := wsViaCep;
    // Realiza a logic
    LCepComponent.BuscarPorCEP(AZipCode);
    Result := MapToResponse(LCepComponent.Enderecos[0]);
  finally
    LCepComponent.Free;
  end;
end;

5. Component Prefixes

When dealing with design-time components in DataModules created to facilitate events, use these mappings: